Making plastic pots more plant-friendly...?

aharriedmom(8B FL Sunset 28)July 21, 2012

I've been reading this morning on the benefit of clay / terra cotta pots vs. plastic pots. Unfortunately, I have a ton of larger plastic pots but very few larger clay pots.

Could the air exchange - gas transfer - aeration issue be helped by putting many little holes in the sides of the plastic pots? For example, taking a heated nail and poking a many, many holes in the sides?

Random observation: I have a strawberry plant in a plastic pot that recently cracked up the side. It seemed to shoot out a ton of new growth since I noticed the crack.

Thanks much!

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No. In fact, plastic pots are better because they are lighter, cheaper, and do not crack in the winter.

Just remember, watering habits are a big part of the end results.

Here is some nice little thai peppers.

    Bookmark   July 21, 2012 at 10:53AM
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tapla (mid-MI z5b-6a)

The reasoning that plastic is better all revolves around the grower, and not the plant. From the perspective of what offers the potential for better growth, terra cotta wins, hands down, over plastic and other materials that are impermeable to gases. Lighter/cheaper/no cracks doesn't = better growth potential, but an increase in gas exchange and the need to water more frequently does.

Adding the holes will also increase evaporative loss from the soil and shorten watering intervals - a good thing as the plant sees it. Poking holes in plastic pots will help a little, but I'm not thinking it's something that once done you would be able to notice a significant difference. I think the biggest plus comes from the soil itself supporting good gas exchange. Still - every little bit has the potential to be helpful.


    Bookmark   July 21, 2012 at 1:16PM
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Here's a link to someone that drilled holes in a black plastic container to make an airpot. Supposedly obtained very good results.

The cannabis growers are some of the more innovative growers around. I don't grow what they grow, but do look to learn from what they try out.

I'm using net pots now for growing seedlings to transplant.

Here is a link that might be useful: Low Cost Vegetable Garden

    Bookmark   July 21, 2012 at 2:01PM
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Hey Al, how are you? I am hoping you are well:-0)

Yes, in general, I have been finding that most of my plants do respond better in clay, but there have been exceptions to the rule in my case. I am referring to my lemon and lime trees which rebel to cold clay pots when it cools here towards the fall and until it warms into the spring.

I have found over the years that clay had been keeping the root system much too cold for their own good in cooler weather. So I have gotten very little top growth and very small root mass.

After 3 years of growing lemons and limes in clay, which has was very minute, they took off after planting in plastic pots. When I upotted the ones in clay, I was surprise to see how little they grew even with the best of care in the gritty and 5.1.1 mix.

Now I am happy to say they have responded well to the plastic because on cool nights, the roots are not as cold as they use to be in clay.


    Bookmark   July 21, 2012 at 2:58PM
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This is why I like the gardenweb. I learn so much on here.

Thanks for the furthur explanation guys.

    Bookmark   July 21, 2012 at 3:05PM
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I've been wanting to try using netpots or diy fabric pots for growing transplants.. glad to hear it works. Does it cut down on circling roots?

I was stunned at how a donated pepper plant has been doing in a metal washer drum... I was sure it would die in the heat. Thanks to the holes, it seems completely oblivious.

    Bookmark   July 21, 2012 at 4:55PM
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tapla (mid-MI z5b-6a)

Good, Mike - thanks for asking. I hope you and Sissy are well.

Actually, there is no discernible difference in root temperatures between clay and plastic per se, though there would be a difference in the amount of solar heat gain because of any difference in the container's color when in direct sun. Still, close to 2/3, maybe 3/4 of the woody material I grow on for bonsai is in terra cotta because w/o question it promotes healthier roots. What clay pots DO do, is keep roots cooler during the summer when high temperatures effects on roots are deadly. This is due to evaporative cooling. Note though, that clay is self regulating in that regard, in that as temperatures cool, evaporation slows markedly, to the point where evaporative cooling's effect on root temperatures is insignificant when air temperatures are cool. Clay is also a better insulator, so it takes longer for soil/roots in clay to change temperatures, which can also work to the plant's advantage as temperatures fall because of the greater lag between root/soil temperatures and ambient temps.

Warm or cold, my experience is - better growth in ANY container that has gas-permeable sides - otherwise, I wouldn't pay for clay when I have access to free nursery cans by the hundreds.

Net pots or pond baskets work great. I've use them for years as intensive care facilities for any plants I acquired that were struggling, and for woody plants recently collected from the wild as candidates for future bonsai. I often use those white containers by Sterilite - the ones with the holes already in the sides. .... not particularly attractive, but very effective.


    Bookmark   July 21, 2012 at 10:38PM
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yellowthumb(5a Ontario)

Hi Al,

I am puzzled by the difference of clay and plastic as well. I use 5:1:1 for Citrus in Clay pots. As Mike indicated, all of them except the kumquat are kind of sulking, even after a year of repot, when I check their roots, their roots stay very small, they just don't go deep. I just repotted my citrus from clay to plastic, most of them only occupy the top part of the pot. After repotting to plastic, I immediately noticed a difference, their leaves perked up and a bit greener. My kumquat, on the other hand, grow beautifully in my big clay pot. But that clay pot is huge and thick. My Camellia and Gardenia are all growing excellent in Clay pots. They have the most amazing root system, occupying every single inch of the soil and teeth white.

My theory is that the air circulation plays a role as well. Even the temperature is low, but when it's windy, evaporation still happens in a faster rate. In north part of the world, we have windy days very often.

    Bookmark   July 22, 2012 at 12:20AM
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^ If clay pots are a better insulator then maybe your container was not heating up as quik as the black plastic. When you live in a cold region then maybe the black plastic will give you better results. So with that said, maybe the black plastic containers could be helpful to the plant, not just the gardener, in climates that are not so hot. Because of not only the color but the material and how thin and quik they heat up.

I lift each pot to find out when it is time to water, either that or watch the plant wilt because it is so dry. Clay is heavy as it is.

    Bookmark   July 22, 2012 at 10:51AM
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tapla (mid-MI z5b-6a)

Here's how I think - and by no means am I trying to put anyone in a bad light because I hold myself to this standard: I can't think of any reason why a plastic pot would outperform a clay pot, and my experience with all my woody material is that they don't. I have at least 150 woody plants in clay or gas permeable pots, one of the reasons being because nursery cans over-heat in the summer sun so quickly, which is a tendency that needs to be balanced against any heat gain there might be later in the growth cycle and early spring, which needs to be balanced against the fact that nurseries use them, so they can't be BAD for plants.

Oh - the standard ..... If I think I see something that doesn't fit with what I know of science, I reject my observations and look for something that does fit what we know, which is why in this case I tend to look for an answer other than soil temperature.

One thing that surprised me is Mike's, "I have found over the years that clay had been keeping the root system much too cold for their own good in cooler weather. So I have gotten very little top growth and very small root mass", which doesn't match my experience at all, and we have similar growing conditions. Without exception, every plant I repot, whether it's in clay or plastic, has exhibited good growth and has produced a root system that has colonized the soil evenly and completely.

Typical root systems of plants in clay pots:



I'm not suggesting anyone should change anything, or that you're wrong .... I'm just saying that a weak root system or reduced growth has never been my experience in clay; in fact, it's been the opposite and something I attribute to t factors. One is the added gas exchange and the other the reduced summer soil temperatures, which wreaks much more have than most people know, and the results of summer root dieback are often not sen until fall.

When root temperatures are discussed as they pertain to nursery cans, the discussion almost always centers around how to MODERATE root temps, which suggests that the key consideration is reducing root temperatures, though I'm not trying to suggest that increasing root temperatures where appropriate isn't helpful - it assuredly is, but I can't help but wonder about how intensely root temperatures would need to be monitored in order to get the full benefit of heat gain in black cans with no detrimental effects from high root temps.

Studies show (see Plant Production in Containers II ~ Carl Whitcomb PhD) that damage from high root temperatures happens very quickly, and roots that are killed may provide an excellent pathway for fungal infection. Honestly .... I frequently see lopsided root systems in black cans resultant of the death of roots near the container walls on the side exposed to sun.

Interesting topic ...........


    Bookmark   July 22, 2012 at 10:51AM
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I am sorry.

I was posting right when tapla was. My last post was a response to-yellowthumb.

    Bookmark   July 22, 2012 at 10:55AM
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pink_warm_mama_1(Z4 Maine)

Will someone please explain - what are net pots and pond buckets? Many thanks.

    Bookmark   July 22, 2012 at 12:52PM
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Al, you know me pretty well. I usually don't question much of what you say anymore because I have learned to have faith in what you teach and how much you know.
I have also come to know you much and appreciate all you have to say.

In this instance, the only way I can prove to myself that clay is not keeping my soil temps cold, or colder longer when my temps start to drop is to take thermometer readings on a cool morning. One in plastic and one in clay.
I would curious to see if there is much difference and how much longer the roots stay cold in clay if so.
If the mix is much cooler in my zone growing in clay, this is detrimental to the growth of certain plants of mine, especially the tropical plants that like their feet warm. My Meyer Lemon and Lime trees do not like cold temps and I question why they have been doing much better than those grown in clay.
I am not talking about summer here, in which I can understand where clay would be better than over heated black pots.

I happen to be lucky in the fact that I do not get the hot summers like most do here, and in fact, most my summers average cooler because I live along the coast. It was 48 degrees here the day before yesterday and 53 this a.m. Just 20 miles west from me can be 10 or more degrees hotter on most days in the summer. I have yet to see 100 degrees and now, it feels like fall already.

Let's see how the thermometer test does on an upcoming very cool morning which will be here before I can even blink, and I will get back to you.

I appreciate your time and Sissy sends you a hug!


P.s Here is a thread you might want to take a look at. If there is any misconceptions there, I would appreciate your input there too. It seems that most of us agree that Meyer Lemons perform better in plastic.

Here is a link that might be useful: clay and plastic benefits

    Bookmark   July 22, 2012 at 1:43PM
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tapla (mid-MI z5b-6a)

Net pots are grow bags - a fabric that aids in promoting exchange of soil gases and 'automatic' air pruning of roots. Pond baskets are mesh containers, almost always of plastic. Do a search for "pond baskets" (with the " ") and many pictures will come up.

I have no problem freely acknowledging that the soil in nursery cans heats up quickly, and that it can be a good thing very early and very late in the growing season. I think though, it takes fairly intensive management to truly take advantage of temperature increases and avoid the effects of temperature excesses because there are many days where it would be an advantage to have soils warm early in the day, only to face the potential for over-heating only a few hours later under sun load. That air temperatures might be in the 60s/70s is not insurance against soil temperatures going into the 100s. This would be especially true later in the year when the solar elevation angle is low and the containers get more sun exposure than in summer when it's closer to 80-90*. IOW, there is bad (excessive root temperatures in summer AND fall) to be taken with the good unless there is ongoing management to both take advantage of the suns rays and protect against them, and this can often be framed within the same day.

Since I virtually never see poor root systems in clay, but regularly see large fractions of root systems killed in dark nursery cans, I like clay ..... but that doesn't mean everyone has to ....


    Bookmark   July 22, 2012 at 1:49PM
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Hey, Al, in case you don't notice, my immature cousins have decided to take part of these forums without my knowledge until just now, using my lap top under the forum name called ,DIRTBITES! They have used my lap top while I was at work and decided to stir things up at these forums due to a huge disagreement with me over growing plants. They have stopped and I send my deepest apologies for their actions to all. Thank you

I will see to it they take no part here again.


    Bookmark   July 22, 2012 at 2:40PM
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Re: mikes cousins, who knew plant philosophies could get so.. passionate. Don't chase them away, perhaps they'll learn something.

If this comes across as snide or superior, please accept my sincere apology. This just happens to be one of my "buttons".

Al, while I totally understand your other points and agree with you completely.. I really, really hate the way you worded this:
"Oh - the standard ..... If I think I see something that doesn't fit with what I know of science, I reject my observations and look for something that does fit what we know, which is why in this case I tend to look for an answer other than soil temperature."

Rejecting your observations without a really good reason is something you never do in science. It's the observations that challenge what we "know" that allows science to move forward at all. The data is the data... you can't cross it out without being able to fully explain it (as an outlier, as due to some other phenomenon, etc).

I know what you meant, but it's just one of my pet peeves.

    Bookmark   July 22, 2012 at 3:51PM
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No worries, Mike... it could happen to anyone. :-)

Though family members or good friends are the last ones you'd expect to commandeer your computer while you're not around, and use it in a negative manner, it can and does happen.

The funny thing is... they forgot to log out with the name and password they made up for the occasion, and return your computer to its original settings. Oops! So, they did succeed in allowing you to easily figure out who the culprits were!

Even if I do happen to borrow my son or daughter-in-law's computer while visiting, I never mess with anything that's none of my business. I don't open their email, check their messages, log in to places they frequent... to do so would be very rude, in my opinion. I'd never do that.

But, stuff does happen... often when we least expect it... so consider it forgotten, Mike. It's no big deal. :-)

Back to pots...

While I do prefer unglazed clay for its porosity, its ability to "breathe" and allow any salts to escape, not to mention its neat, natural look, I do allow that some micro-environments call for the use of plastic.

As example, the ledge of my window can get fairly chilly in winter, but it's also the best source of natural light... so I do keep a couple of smaller plants in opaque plastic.

Clay can have a tendency to get cold that close to a window in winter... especially after watering... so I do have to compromise for a couple of my smaller, more tender plants.

Most of my plants are in clay. It's just what I prefer, though I think we have to use what works best for the unique environments we all have to deal with.

    Bookmark   July 22, 2012 at 4:55PM
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yellowthumb(5a Ontario)

At around 11:00AM, We have full sun and I checked the pot surface temperature, it was hot, very hot, while the air temperature is only warm. Then I stick my finger inside the pot, close to the sunny side. It's very hot as well. Definitely no roots will survive that kind of temperature. Then I checked the other pot which I sprayed with white paint. It was only warm. Now I am considering paint all my black plastic.

    Bookmark   July 22, 2012 at 5:19PM
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tapla (mid-MI z5b-6a)

Hi guys! No worries Mike - we got it all straightened out. ;-)

What I meant about the rejecting observations is, I try really hard NOT to make up science to fit my observations. It's much more fruitful if we trust what we KNOW of science and look for scientific explanations than to simply make up explanations because they seem like a reasonable fit.

To be sure - I'm not suggesting that's the case here - that's just how I roll.


    Bookmark   July 22, 2012 at 9:40PM
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That's how I like to roll, too, Al... "just the facts, ma'am", as they say. ;-)

Science and physics have a lot to offer when it comes to gardening, both in containers and in the garden... as different as the twain are. And as we know, there remain a lot of fallacies floating around that have no basis in fact or science.

Commercially, gardening is an industry like any other; the object is profit... not necessarily the truth or facts. Selling is the name of the game, by attracting consumers to spend their money.

Why people automatically believe old myths, I'm not sure. And since good research involves checking more than one source and making a determination based upon as much information as one can find, along with experience, logical thinking, and common sense, I don't know why people grab the first source they come across and use it as gospel truth.

If Al links a source, I'm assured it's not the first one he's ever read, given his many years of experience, in depth research, and his logical approach to problem solving... not to mention his success.

I also allow that growing is not a "one-size-fits-all" operation, either... there are many variables to consider from grower to grower, season to season, and from environment to environment... though the basic facts remain the same.

For example, what works wondrously for me could present problems for a grower in the desert heat of the southwest, or for a grower that strictly grows indoors. I think it's best to know the facts, the science, and apply it to one's own micro-environment. Certain small changes or adjustments may have to be made in order to gain the most in optimum growth.

For growing in containers outdoors, I prefer to use unglazed clay. When I have to use plastic, I like to use lighter colors, or the orange designed to mimic clay. Where that container is placed will make a difference in temperature, also.

I dislike black plastic because it does seem to multiply the heat of sun... as least, this is what I've observed.

But then, this year has been quite different than previous ones, as well... at least, it certainly has been in my area, the Midwest. We've had earlier, hotter temperatures, and drought conditions to deal with.

In a normal year, I wouldn't have to irrigate so early, or quite so much. This year, I found myself hauling out soaker hoses and sprinkling equipment a lot earlier than I normally would, and using more water than I would in a different year.

My personal plants in clay or lighter plastic are doing much better than some of our stock plants, which are showing stress caused by the heat, sun, and being encased in black plastic, which is what I have to work with at the moment.

To summarize, I would say that there are the basic facts as we know them... and there will be adjustments to be made depending upon individual environments and conditions. To grow optimally within the confines of containers, it takes involvement and close observation. The person that doesn't bother with facts, and waters once a week whether needed or not will not have the same success as the grower that desires to learn more and is involved, observing closely things like sun movement, temperature, their individual micro-environment, using a medium and fertilizer that works best in their environment, etc...

There's no such thing as a "green thumb"... it's all knowledge, with experience mixed in.

    Bookmark   July 23, 2012 at 9:17AM
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Well said, Jodik.

I have to say that was worded very well.

I always have used plastic containers but I must give some clay pots a try after hearing all of this.

    Bookmark   July 23, 2012 at 9:30AM
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Your kindess and understanding are always appreciated good friends!

Jodik! What a breath of fresh air to see you around these parts again. Please, stick around this time:-)



    Bookmark   July 23, 2012 at 11:56AM
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Well, that does it. I'm gonna have to get my sewing machine out this winter, buy some eco-felt, and make a bunch of fabric pots. I have 5 gigantic smartpots, but it's not enough. I unfairly judged them last summer by using poor growing media and not fertilizing enough (with nitrogen).

They're too expensive for me to buy when I know I can make them myself. The other problem is, they're so darn ugly! What I actually have are "camo-pots", a knock off by a company that makes them in lots of wacky colors. At the time I thought the camo-design was random and just wanted something other than black, but it's apparently meant for cannabis growers to hide their growing operations in the wild. Still, all their options are too ugly to use in the front or side yard.

I want to do something along the lines of this, but maybe more.. umm.. manly?

Here is a link that might be useful: Etsy Fabric Pots

    Bookmark   July 23, 2012 at 5:46PM
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uscgardener(USDA 9 Sunset 20/21)

Hi everyone, I'm delurking to ask, do the fabric pots really work? From what I've been reading, people have mixed results. Is this due in part to the mixture they are using in the fabric pots? If using the 5:1:1 mix, would that dry out too quickly?

    Bookmark   July 23, 2012 at 6:28PM
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tapla (mid-MI z5b-6a)

How well they work depends in part on how you use them. If you set them on the ground, you can treat them the same as you would a raised bed, so heavier mixes that might not be the best choice in a container might be quite usable in a smart pot - with the earth as a wick to remove excess water. If you set them on a nonabsorbent surface, like a deck or concrete, they'll behave essentially like a container.

So YES, they work, and can be made to work quite well with a little experimenting on your part. Welcome in from the shadows. ;-)


    Bookmark   July 23, 2012 at 7:38PM
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I've never used a fabric pot, so I have nothing to offer in experience... but what Al says makes perfect sense. The ground would act as a wick, so placing them directly on the ground would be what I'd try. And I'd imagine you could get the proper type of material in a variety of colors... I'd choose something light. To make them a little manly, you could always stencil something on them, or sew a patch or two on... maybe a few leaf or garden tool shaped patches... I don't know... I'm female, so I'd probably do some border stenciling in a pretty pattern or something.

If I were to use them on a different surface, I'd use a more sturdy, aerated, more inorganic medium that would allow for better overall drainage... again, also allowing for my individual growing environment.

I'll try to stick around a little more, Mike... but life is busier now than it ever has been, and I've been left to figure out how to manage everything on my own, and make the business beneficial for everyone who had a hand in it, to boot. So, basically, I'm running myself into the ground to make enough money to survive. Life got a little tougher out of nowhere... but it's not the first time we've been pushed in a hole, and it won't be the last. If we could figure out how to get this black cloud from following us around, or find the winning lotto numbers, everything would be peachy! ;-)

But seriously, every morning that I can get out of bed by myself, without help, I know it's going to be a good day. Life hasn't beaten me yet, and I'm not about to let it! If we could just get a little rain, I'd be happy. :-)

Happy Growing!

    Bookmark   July 23, 2012 at 10:17PM
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yellowthumb(5a Ontario)

I have been using smart pot for three years now. I have to say that I have mixed results. The best results come from my fig tree, this is a 45 gallon pot, filled with a light mix made of 75% peat and 25% perlite. The fig is just so vigorous. Its roots filled the pot in no time. The other great success is my banana shrub in 5:1:1. A tropical tree really. The first year in it was OK, but this year it took off with the most compact and beautiful growth. So vigorous, it blows off banana shrub from nurseries. I also have been using smart pots with basic top soil for Tomato, growing better than in ground.

The disappointment came from Gardenia and Camellia in gritty mix. It's growing slowly, I don't think I watered them properly, maybe it's draining too fast. When I finally repot them, I find some dry pockets and dry sides as well.

The down side with smart pot is that I find them too shallow and hard to find a saucer for the large pots. What you guys been using for saucer for those oversied pots.


    Bookmark   July 23, 2012 at 10:32PM
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First off...Jodik:-)))))))))))))))))!!!!!!!!!!

Now, I will actually share some of mine with you, and as Al had mentioned, I started using them for ICU purposes too. Many plants handed to me were just horrible, on the brink of death, and they seem to be working for me. I had no time to waste, so I wanted to try them before the summer was over and I am seeing remarkable recovery/results on all of them.
I still use the 5.1.1 mix or something to that degree whether in a fabric or fabric supported by plastic container for even more air circulation.

I have not been using them long enough for a definitive go and buy them spree, but I can say that thus far I am happy with them. I really don't need them with the mixes I already use, but hey, what's wrong with even extra oxygen in my case and a little fun. They are certainly much lighter than clay and it's much easier for me to judge when to water!

Here, take a look:-)

Oh, HELLO Yellowthumb!

My variegated fragrant Olenader

A Citrus tree I am saving responding quite rapidly

A Brown Sugar fruit tree from the tropics giving me fruit. Now this one in just in fabric and II rest on the earth to use the earth as a wick. I did notice that the bottom always seems very damp even days after watering, even in the 5.1.1 mix. I shall have to tweek this and use some kind of saucer that does not let in sit on a flat surface when I bring it in.

Now, the only concern I have for any of these kinds of pots is harboring bugs such as EARWIGS.

Jodi..This is for you:-)

    Bookmark   July 24, 2012 at 10:09AM
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It is nice that there are many different containers to try out there. Like I said, watering habits and nutrition are very important.
This plant was grown in a regular plastic standerd #2 container.

    Bookmark   July 24, 2012 at 11:18AM
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uscgardener(USDA 9 Sunset 20/21)

Mike, thanks for sharing those pictures and your experience with the smart pots. In the first few pictures, is that a pond basket the smart pot is inserted into? Is that mostly for structure (fabric pots a bit floppy), or is there another reason to use them?

I am working on "green-ifying" a useless concrete area the previous owners of my house put in... It would take too much demolition to remove it, so that is not an option. Not only does the concrete heat up greatly during the course of the day, but it is also on the west side of the house! Awful afternoon sun. My plastic pots are very hot to the touch by evening, which I'm sure is not good for the plants. I'm wondering if the fabric pots will help a little with the root baking situation. I have been trying to shade most of them and elevate the pots maybe 6 inches above the concrete.

    Bookmark   July 24, 2012 at 5:00PM
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I had a terrible experience using topsoil in very large 30 gallon smart pots for tomatoes. Actually it was Home Depot "topsoil", which I believe is mostly sand and sifted forest product compost, mixed with super expensive and utterly useless Lady Bug organic potting soil, which includes bunch of coconut coir. I really have no idea what I was thinking. Using crushed pine bark alone would have been so much better, and cheaper too!

Anyway, my tomatoes suffered, had yellowing from probable nitrogen tie up. Also, curled up and crinkled leaves, I assume from the incredible heat of that summer.. but still gave me a paltry amount of fruit. Nothing like my tomatoes in the ground though. That said... they never wilted and seemingly never needed water. At the time I figured the the soil was too water retentive. But now I'm thinking it's more likely that the soil simply wasn't heating up the way I expected from experiences with black plastic nursery planters. That combined with the sheer volume of soil greatly attenuated the need for irrigation.

The tomatoes and watermelon I grew this year in are a peatless version of 5:1:1 and could not be happier. Point being, I now think fabric pots probably completely do away with the root baking situation.

Correct me if I'm wrong, but isn't concrete itself a good wick, absent any surface paint or sealant? I wonder if raising fabric pots off the concrete would be counter productive?

    Bookmark   July 24, 2012 at 10:50PM
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uscgardener(USDA 9 Sunset 20/21)

Greentiger, that is a good question that I don't really know the answer to. I assumed direct contact between the pots and the concrete would be bad due to how hot the concrete gets in the middle of summer heat, but that was just a guess. To be honest, I was also noticing some water staining (from drainage) on the concrete whenever I moved the pots, so that is also why I started elevating them. I am glad you tried the 5:1:1 in the fabric pots; I really want to finally make the leap and try 5:1:1 in something. :) I have been seeing everyone's wonderful pics of plants grown in 5:1:1 and am very impressed.

    Bookmark   July 25, 2012 at 1:38PM
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uscgardener(USDA 9 Sunset 20/21)

Mike, why did you say you worry about earwigs in fabric pots?

    Bookmark   July 25, 2012 at 1:51PM
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pink_warm_mama_1(Z4 Maine)

Will someone please explain what gas exchange has to do with container gardening?

    Bookmark   July 25, 2012 at 3:05PM
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Container medias must have sufficient pore spaces to allow free movement of gases. Plant roots constantly undergo respiration. Respiration is a cellular process that burns sugars to create energy (sugars are generated by photosynthesis in leaves). Cellular respiration consumes oxygen and releases carbon dioxide (CO2) as a byproduct. There must be sufficient pore spaces in a mix for plant roots to acquire oxygen and expel CO2.
A mix that allows you to water frequently will fit the bill:-)

Uscgardener: I say this because I hate earwigs and they seem to hitch a rise and hide on anything that they can hide in. I wonder if they go crawl into the fabric or spaces between the fabric the plastic on the pots I use?

By the way..You could call it the 5.1.1 and at times the 911 mix, if you are looking to save any plants in severe decline from water retentive mixes.

Also, those fabric pots with the plastic are made that way. i have a great Hydroponics store that sells both the frames and the material. I LOVE them!

Time for


    Bookmark   July 25, 2012 at 10:09PM
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I might mention another variable is the plants themselves. In particular, I find that peppers grow best in black containers, and seem to like warm roots. My peppers in ground (unlike other plants), never do as well as in containers, but do better when black mulch is used on ground as well. Lighter colored containers don't do as well for me for peppers. Roots always look perfect, white herringbones, so I don't think the heat bothers them much. But I do think peppers are an exception. Things like tomato, lettuce and basil do better in lighter colored containers.

    Bookmark   July 26, 2012 at 8:24AM
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aharriedmom(8B FL Sunset 28)

Love all the replies! Thanks for all the information to think about and process.

    Bookmark   July 26, 2012 at 8:36AM
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valentinetbear(z6 PA)

Ack, the science and complication is giving me a headache.

Here's my take. I'm a container gardener by default. We bought a house with a 16' X 16' backyard made of cement. And then I got (and then he got) into gardening. And then we both became disabled, so we have to garden on a tight budget.

Terra cotta is more costly and breaks too easily. (Most of my old terra cotta containers are now shards for covering drainage holes.) We tend to repurpose containers for gardening. Because of that, I also know old grills work fine for our basil. (Not so well with the fennel, but we never grew fennel before, so didn't know they grew that tall. It's a tabletop grill. lol) A galvenized tub has been holding our prickly pear cactus for years. Oh, and are garlic chives are in an enamel collander.

5-gallon plastic buckets hold most of our tomatoes. (Oe larger plastic container holds the Cherokee Purple and Early Girl.) Two of our patio tomatoes have gone past 5 feet already and the tomatoes are big enough for three tomato sandwiches with thick slabs. We grow two per container, too.

Most of our garden are in plastic containers of one kind or another. It's just cheaper than terra cotta, and, because we're both disabled, bringing in a lot of pots to avoid winter breakage isn't easy. We do have a grow light, but I want to save all tender perennials, so I put those in terra cotta or ceramic pots and jam them around our one and only grow light.

Our succulents tend to grow in porous pots, too, but they're smaller, so not as costly.

I do get porous is better, but I'm no eagle-eye container gardener to tell any difference. We merely water well every early evening, and during heat waves, water in the morning, too, and buy new cheapo containers when the old ones crackle from being out all year. (About every 5-7 years, whereas the terra cottas tend to get dropped or break every 4-5 years.)

    Bookmark   July 27, 2012 at 6:28PM
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I think the point being made here is that simply put..Growing in clay far excels plastic for any plant from a plants perspective, not that we sould all grow in it.

I in fact use all kind of different pots, from plastic to clay, but if I am going to do what is best for my most prized, usually a plant that I have to winter indoors, I am going to use clay. It is a personal choice and an easy one at that.

I will usually provide what I know is best from the plants perspective, but I too fall short on many occasions.:-)

Good growing.


    Bookmark   July 27, 2012 at 8:11PM
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Very nice, Mike! Good job, as always! :-)

I've said this elsewhere many times, but I'll repeat it again for anyone newer to the forums or to growing...

If one of the first things I had ever learned about growing anything, all those many years ago as a youth, is that Mother Nature provides a very different environment than the one we can accurately and adequately maintain within the confines of a container, therefore a slightly different approach is necessary... I'd have been light years ahead of the learning curve, and my success would have begun much earlier in life!

Unfortunately, a lot of what floats around is myth, misinformation, fallacy, or information that doesn't quite fit everyone's very different and individual growing environment and climate. The concepts and stories "out there" are varied and one size does not fit all.

The industry, itself, is very little help as they thrive on profit... not necessarily on shared information that works. We're talking about corporations where the main goals are to keep consumers coming back to spend more money, keep profits coming in, and keep their shareholders happy. One industry is pretty much like the next... and they all contain "scientists" and/or "experts" that are paid to write reports or articles touting the latest and greatest in growing products... many of which turn out to be worthless. It's all about marketing, all about money, and oodles are spent to test market products... right down to utilizing the right words, the right packaging colors or shapes and sizes, etc... all to appeal to a nation of consumers.

Now, I realize that not every hobby grower wants to get quite so involved in the learning process... but the reality is that there is no such thing as a "green thumb". Growing healthy plants on a consistent basis in pots has nothing to do with luck... a "green thumb" is nothing more than knowledge and observation... knowing some of the very simple basics behind plant growth, and knowing the differences between growing in the ground and growing within containers... the two being worlds apart.

Think about it for a moment... Mother Nature has a virtual army of creatures, both large and microscopic, that help to break down dead and decaying plant matter and other things into usable nutrition for the plants' growth cycle, and keep everything in balance, including drainage and aeration. Within a container, we don't have this same scenario, at all... and any attempts to duplicate it might work for a short amount of time... but long term, that same army and that same balance cannot be artificially maintained. We're talking about worms, insects, nematodes, fungi, bacterias, birds and other larger or smaller creatures that leave scat (fertilizer before it's broken down) behind, that said army works at breaking down into food that a plant's roots can uptake and immediately use to benefit, continual aeration of the soil, drainage of rain water, space for roots to spread out and dig deep, etc.

When I was younger, I never really thought about all these variables much... and it led to a lot of frustration, disappointment, a lot of failures, a lot of trials and errors... and a lot of lost plants, some that were rather dear to me, given as gifts.

The day I stumbled onto Al's main article, "Container Soils - Water Movement & Retention", was the day the tables began to turn for me. Al had taken a plethora of science, physics, and other important, vetted growing information, added his many years of professional experience and study, and broken it down into very easy to read and understand layman's terms. I felt like I had just struck gold! The article he wrote put to rest a lot of myths, gave me a lot of very logical, common sense information, and gave me a new lease on container gardening!

Since the time he first posted that article, it has rolled over due to limitations on posts over a dozen times, which tells me something very important... the concepts contained within that article are very sound!

But it's not enough to just copy his medium recipes and think that's all there is to it. It's the CONCEPTS that are so very important... understanding HOW and WHY the ideas work... and realizing that since we each grow in a slightly differing micro-environment, some things will have to be adjusted to suit your own, personal growing environment.

For example, a plant growing in a container on a patio in Arizona will require slightly different care and medium adjustments than a plant grown on a patio in, say, Minnesota. So while the basic concepts remain the same, there will be certain variables that change from area to area, gardening zone to gardening zone, and environment to environment... while the basic science, physics, and the concepts, themselves, remain as a guide.

I've read countless books, countless articles in magazines and on the internet, and read so much opinion and personal experience it would make your head spin! Some of the books were way beyond my realm of scientific understanding, or the simpler ones all said the same things. Articles and blogs read were all over the place, as are general opinion and personal experience. I've taken advice offered from many different sources, and tried a lot of different ideas... but to my detriment, I never realized that none of it came from an exact duplication of my own micro-environment and growing conditions. I was not adjusting for it, and not much of what I read kept that thought at the forefront.

Since reading Al's first article and applying the concepts I learned to my own environment and growing conditions, I've remained an apt pupil of his teachings. Al, better known as 'tapla' on GardenWeb, is not just another member... for those who don't know him. He speaks publicly before large crowds on the merits and information necessary to be a successful, knowledgeable grower. His bonsai experience and knowledge have yielded some of the most beautiful specimens I've ever seen, and his own yard is filled with beauty, healthy plants, and success stories. And best of all... he freely and generously shares what he has researched and learned here, with all of us. :-)

Some might think his demeanor a bit cool, or formal and science oriented... as opposed to being personal and filled with smiley faces... but that's just his style. Anyone who truly knows him realizes what a wonderful person he is, and how generous and patient, taking the time to explain detail and nuance, helping people locate medium ingredients within their own areas, and giving a plethora of individual advice and help when people ask.

To summarize, I think it's important to have a good grasp on the basics of how plants grow, what they need, and that the world of growing should be split into two basic categories: growing in the ground, and growing within the confines of containers.

To me, this means taking a more organic approach to growing in the gardens... and using a more inorganic approach to growing in pots. And that would include any kind of container.

We must remember that each of us lives and grows in a different micro-environment, whether we live halfway around the globe, or down the block. Even slight variations can mean slight adjustments are needed.

But I think the most important things to remember are that it's the CONCEPTS we're mainly after, and knowing the HOW and the WHY of what we're doing.

Happy Growing!

    Bookmark   July 28, 2012 at 11:29AM
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Clay pots provide a healthy environment for most plants. The porosity of clay allows air and moisture to penetrate the sides of the pot. This moisture and air is utilized by the fine roots located at the edge of the soil ball. Clay pots also act like a wick to remove excess moisture from the potting soil. This can be looked at as both an advantage and a disadvantage depending upon your watering habits.

    Bookmark   October 17, 2013 at 6:24AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

I would prefer to have clay pots for some reasons, but the deal-breaker issue is weight, so most of my pots are plastic. It never ceases to amaze me how much more water can come out of a pot by tilting it (assuming there's at least one hole at/near an edge, which I make if necessary.) That's one way to overcome excess moisture. I don't find it necessary while plants are outside for summer, but wouldn't think of skipping it while inside for winter. I even bought a squarish plastic bowl to sit pots in a tilted position, hands-free, after watering.

Well said, Jodik. And Stevethumb. I didn't read any farther back than that, but the word tilt doesn't appear here, yet. Don't want to get involved in the debate, but this is how I deal with my plastic pots.

    Bookmark   October 18, 2013 at 12:53PM
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Well hello all!

Since this thread started I have realized that most all my plants do very well in clay EXCEPT Lemon Meyer trees and Banana plants in my area...They do well when temps are much warmer than these cold nights in clay, but it does not stay that warm for long, Lemon Meyer hate cold roots as do Banana trees.

All my Lemon Meyer trees planted in plastic are growing at a much faster rate than those in clay..Once I wrapped a piece of plastic on my Banana tress in clay on these cold 40 degree nights, the leaves stopped drooping severely and are doing fine now.

Touching a clay pot that is has wet soil in it can feels way much colder out the outside of it verses touching a plastic one....Just my observation:-)


    Bookmark   October 18, 2013 at 7:27PM
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Hi Mike

Just wondering, applying the same logic to a very hot deserty climate like mine, clay pot will not do better than plastic since it would get extremely hot inside the soil which will be quite detrimental for the plants - If the outside soil (air) temps are close or above 95F, the inside soil (root) temps could be at least 10 degrees over that in a clay pot? Am I right?

    Bookmark   October 18, 2013 at 11:37PM
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seysonn(8a WA/HZ 1)

I just bumped this thread.
I read a small fraction of the discussions. There are good point. So here is what I think.

Factors that can differentiate Clay and Plastic , IMO, fall into 3 categories:

1- Economics: Plastics cost less and won't brake, crack, will last longer.

2- Climatic Requirements: In hot, dry climates clay is better because it offers better protection for the root and eventually to the plant. However, in cooler, rainy, cloudy climates(Like I am in) plastic (especially black color) is advantageous. It absorbs solar heat more and stays warmer longer. .

3) Ecstatc , Visual and Feeling Effect. Where money is no object, in general, clay pots with ornaments, glazing ..etc wins over some el cheapo plastic. And this is irrelevant to their function and practicality.

So then , for me, to grow few annual plants (peppers) plastic pot serves my objective. But if I was going to pot a house plant, to put is in my living room, I would not use a plastic pot.

Then there are other container options . but we won't get into those.

    Bookmark   November 2, 2013 at 8:54AM
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seysonn(8a WA/HZ 1)

Another Alternative.

From what I have read so far, I have not seen anybody talk about wooden containers, pots.
Being a woodworker, I make some planter from cedar lumber. I like it better than clay. The advantages of cedar over clay are: They wont break : They wont crack . But at the same time they are porous too. Of course, wooden containers/planters are for outdoor.
But if you want to buy them they can be expensive. If you can make them yourself, it takes time and efforts. So there are always trade offs.

But IMO plastic pots are more convenient, practical and economical for annuals like peppers, eggplants.

    Bookmark   November 2, 2013 at 8:43PM
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albert_135(Sunset 2 or 3)

I've AAADD, bad, and I may have missed it. Please tell me I missed it. You see I scanned this entire thread and I did not see were someone anyone has measured the temperature inside and outside plastic pots and clay pots and reported their findings.

This post was edited by albert_135 on Mon, Nov 4, 13 at 15:05

    Bookmark   November 3, 2013 at 2:16PM
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I just did that. (I'm in NZ) The air temp is 19C. I measured a few plastic and clay pots in gritty and 5-1-1 mixes and they are all 18C.

    Bookmark   November 10, 2013 at 7:46PM
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seysonn(8a WA/HZ 1)

I did not see were someone anyone has measured the temperature inside and outside plastic pots and clay pots and reported their findings.
You are right. But nobody is going to set up a laboratory condition to study this. All we can do is some general observations and analysis. It is a mttar of physics and heat transfer. HERE IS MY TAKE ON THE SUBJECT:

If the pot is at direct sun, it will get warmer than the air ESPECIALLY if it is black and dull grey. Some of that heat gradually will be transferred into the contents in the pot. Because the potting medium is a LOW heat conductor, it will take a LONG time to heat up the medium.( We ignore the effect of cooling by winds and breeze.)

BUT if the pot is mostly shaded(which most likely is) then the pot cannot get warmer than the ambient temperature. If the pot is made of THICK clay it will have a much bigger reservoir of heat energy than a thin plastic and it will stay warmer longer.

Another factor is watering: If you water your plant in the morning with cold water, the contents will be almost close to the temperature of the water. So it will take quite a while for the plant roots to get heated, even with the pot being exposed to direct sun.
If too much heat is your problem choose a white color container, that will reflect/radiate good part of sun's rays. But in general, when the season progresses and temperatures climb, by that time plants like tomatoes, peppers are grown enough to shade the pot, especially when the sun is pretty high and shining mostly on top of the plants anyway.

    Bookmark   November 11, 2013 at 12:08AM
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Pardon the newbie question here but I am a (for now) indoor houseplant only grower. I have tried using clay but the pots always gets moldy (I'm in New England). Also, the soil dried out so fast I couldn't keep up with it. So I thought it would be better to use plastic. I don't use a lot of lights. I do have a couple but nothing fancy, I'm just your average houseplant grower who wants to do better.
Thanks to Al and this forum I know have a better understanding of soil. Do you think my previous problems with clay were due to poor soil? Or...?

    Bookmark   November 12, 2013 at 8:03AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

By moldy, do you mean white crusty stuff? That's salt deposits.

Having to water often is great, for the plant, so clay helps with that since it dries more quickly. If you don't have time for that, plastic may be your choice. In either kind of pot, a 'soil' that is comprised of chunky particles with tiny air pockets between them is best, from the viewpoint of the plant.

    Bookmark   November 12, 2013 at 9:32AM
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Thanks for the clarification. I would get the white salt deposits too, but I also get this ugly grey fuzzy mold. I would just periodically while it off with paper towels but it always grew back.

    Bookmark   November 12, 2013 at 9:40AM
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Dean Munt

I loved all this info thank you

I made this for myself and decided to ask if any of you would like to try one?

    Bookmark   March 14, 2015 at 6:24PM
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