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Growing medium...leave in bad soil, or repot in gritty mix??

Posted by i_love_my_cat TX - 7b/8a (My Page) on
Wed, Dec 8, 10 at 16:17

So, I'm very new at growing plants...and have a question about growing mediums. At the moment, I have two angel-wing begonias and a rex begonia (with two more rexes on the way), which I'm growing in African violet mix. I also have a dumbcane, a clivia, zebra plant, chenille plant, an aroid palm, and the obligatory poinsettia, which I put in "all-purpose potting soil" that I purchased in a bag at the local garden center. (I chose these soils based on information I got from my houseplant books.) All of the plants are in a northeast window, are being grown in unglazed clay pots, and "seem" quite happy (are growing, good color, etc). Although, as the weather is getting colder, I don't seem to be getting as much new growth...but am assuming that's normal?

However...I have noticed that the "all purpose" potting soil is looking really, well, bad. It compacted significantly after just a few waterings, which made me worried about whether the plants' roots are getting enough oxygen. And, it's also gotten really hard, even when moist.

So, I decided to do some research beyond what my books say regarding growing mediums and found all of the posts here about the "gritty mix." My question is: What is best for my plants at this point...to leave them in their current soil, or to go ahead and repot them in some gritty mix? If repotting is the best option, should I wait until spring, or go for it now?

Thank you!!


Follow-Up Postings:

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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a MI (My Page) on
    Wed, Dec 8, 10 at 17:09

I think I would try to work with what you have for now, and repot in the spring or summer when the plant will be in a more robust growth phase - unless you see marked decline, then I would probably do an emergency repot. Working with what you have, means taking steps to deal with water-retentive soils and the build-up of soluble salts and sogginess/compaction that accompanies them.

It's not too early to start planning or gathering ingredients for a soil you'll be making in the spring or sooner. People often suddenly decide to make a particular soil because so many others are having good success with it, only to discover that they can't find the ingredients at the last moment. This leads many to substitute what they think might work, often with results not as favorable as what they might have realized if they had done some pre-planning.

I did a lot of experimenting with the gritty mix before I started talking about it on the forums. I had actually started discussing the 5:1:1 mix of bark, peat and perlite, long before I dared to suggest the gritty mix would work well. The basic recipe for the gritty mix is simply a combination of ingredients that I have found to to be the best way to incorporate a concept into a soil. The concept is, maximizing root health and thus plant health by combining ingredients that ENSURE very good aeration for the life of the planting, while still providing good water and nutrient retention.

If you make sure you're familiar with that concept, and understand what it takes to provide those conditions for your plants, you have something much more valuable than a recipe. ;o)

Let me know if you want a link to a thread that has most of the information you'll need for an understanding of why well-aerated, fast-draining soils work so well.

Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Al,

Thank you so much for the reply! I will wait until spring...but have already started tracking down the supplies for the gritty mix. Have some turface on the way. (-:

And yes, please, I would love any links you have that would be useful. I did a lot of searching through the forum and reading yesterday, but am sure there is much, much more here.

One very useful thing I picked up here yesterday was to check through the drainage hole in the bottom of the pot for moisture vs. sticking my finger into the top of the soil. I was planning on watering yesterday, as the top inch or so of the soil felt dry, but when I checked through the hole...very moist. So, I decided to hold off and re-check today. I'm wondering now if maybe I've been watering too often...since I'm relatively new at this, I suppose it's possible I've been giving them too much water, and they just haven't shown signs of it yet. So, very glad I am figuring all of this out sooner rather than later!

Lori (-:


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a MI (My Page) on
    Thu, Dec 9, 10 at 14:42

First, I'll link you to a thread that has almost 1,700 replies/posts to it. It explains how water behaves in container media and why it behaves that way. It explains why gardening and container gardening are so different. Whether or not you choose to adopt one of the soils I use.suggest or not, the information in this post about container soils
will serve you very well, no matter what type of container gardening you enjoy.

If you are having issues with your plantings because of your soil choice, this thread, about dealing with heavy soils has a lot of tips on how to get the most out of a peat-based commercially prepared soil.

You might have read the thread here on this forum that was specifically devoted to a discussion about houseplant soils? If not, it might be worth the read. ;o)

You said, "...very glad I am figuring all of this out sooner rather than later!" and that is a great attitude. I've helped a lot of people improve their growing skills, but husbandry (growing plants) is not the only area in which I provide help and information needed to make decisions much more critical than those related to tending plants. As a CCW (carrying concealed weapons) instructor and an instructor in several other firearms disciplines, as well as a hunter's safety instructor, I am exposed to a very wide range of student's attitudes and skill sets. The people who always, without fail, progress the fastest are those with the right attitude. Often, I'll get people who have been in the shooting sports for years, practicing unsafe or self-limiting habits. It's much more difficult to get students to unlearn the bad habits and let loose of their rigidity than it is to take someone new to a discipline and start from scratch, thereby avoiding the need to unlearn bad habits.

In many ways, growing plants is like the shooting sports. It's not uncommon for me to have a student (often a woman) that is completely new to a discipline, out-performing someone who has been at it for 'all his life' by the end of the first lesson. The more experienced person arrived with what should have been a better and more complete skill set, yet the less experienced student is able to outperform him by simply following directions.

Obviously, it's never the best course to simply follow directions w/o knowing why, but in husbandry, as in many other disciplines, it's quite possible for a newbie to outperform someone firmly entrenched in habits that are self-limiting, because they are set free by their positive attitude. I've seen it happen over and over again; and I'm sure everyone who has ever tried to teach someone how to do something knows how important attitude is to learning and success ...... so keep smiling and keep learning. I promise you won't regret it. ;o)

Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

I've had an extensive indoor plant collection since the house plant craze of the 70's. From that era, I still have a complete collection (39 issues) of the magazine HOUSE PLANTS & PORCH GARDENS -- anybody here remember that publication and wish there was still a good periodical devoted exclusively to house plants?

I used to mix my own potting media, but for the last 10 yrs or so, I've used packaged mixes because there came a point when I could no longer readily find quality ingredients in my locale. Often, the peat I purchased was so fine that it resembled powder; vermiculite particles also became smaller and smaller; and it became impossible to find horticultural charcoal unless I was willing to go to extreme lengths.

Now I simply rely on packaged soil mixes. Sometimes I add sharp sand or perlite to ensure better drainage, and, depending on the plant, I might incorporate a bit of lime. I still pay careful attention to watering, air circulation, humidity (especially for certain plants) and applications of dilute fertilizer, but I don't obsess as I once did about potting media. I fully understand, however, that what is working very well for me and my plants may not be everyone's idea of good house plant culture.


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Thank you, Al. (-: Keeping an open mind and always trying to learn new things are attitudes that serve me well, I think!

My turface has arrived, and I was able to find the other gritty mix ingredients locally! I will wait until spring to repot, as advised, but will start putting all of my new plants in the gritty mix now.

Thank you also for the links...spent hours reading them. (-:

Jaxon - Do you do anything to help your packaged soil drain? I have some plants that are stuck in "all-purpose" potting soil for a while longer, and the lower layer of soil stays moist for forever. Al sent me a link to a post which describes some tricks for working with heavy soils - was great info.


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Yes, I-Love-My-Cat, I do sometimes take steps to help my packaged soils drain more efficiently. I addressed that concern in the second sentence, final paragraph of my post just above.


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a MI (My Page) on
    Sat, Dec 18, 10 at 11:33

Obviously, I think the grower's soil choice when establishing a planting for the long term is the most important decision he/she will make. There is no question that the roots are the heart of the plant, and plant vitality is inextricably linked in a hard lock-up with root vitality. In order to get the best from your plants, you absolutely must have happy roots.

If you start with a water-retentive medium, you cannot improve it's aeration or drainage characteristics by adding larger particulates. Sand, perlite, Turface, calcined DE ...... none of them will work. To visualize why sand and perlite can't change drainage/aeration, think of how well a pot full of BBs would drain (perlite), then think of how poorly a pot full of pudding would drain (bagged soil). Even mixing the pudding and perlite/BBs together 1:1 in a third pot yields a mix that retains the drainage characteristics and PWT height of the pudding. It's only after the perlite become the largest fraction of the mix (60-75%) that drainage & PWT height begins to improve. At that point, you're growing in perlite amended with a little potting soil.

You cannot add coarse material to fine material and improve drainage or the ht of the PWT. Use the same example as above & replace the pudding with play sand or peat moss - same results. The benefit in adding perlite to heavy soils doesn't come from the fact that they drain better. The fine peat or pudding particles simply 'fill in' around the perlite, so drainage & the ht of the PWT remains the same. All perlite does in heavy soils is occupy space that would otherwise be full of water. Perlite simply reduces the amount of water a soil is capable of holding because it is not internally porous. IOW - all it does is take up space.

If you want to profit from a soil that offers superior drainage and aeration, you need to build it into the soil from the start, by ensuring that the soil is primarily comprised of particles much larger than those in peat/compost/coir, which is why the recipes I suggest as starting points all direct readers to START with the foremost fraction of the soil being large particles, to ensure excellent aeration. From there, if you choose, you can add an appropriate volume of finer particles to increase water retention. You do not have that option with a soil that is already extremely water-retentive right out of the bag.

I fully understand that many are happy with the results they get when using commercially prepared soils, and I'm not trying to get anyone to change anything. My intent is to make sure that those who are having trouble with issues related to soil, understand why the issues occur, that there are options, and what they are.

Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

I love my cat.....let's discuss your care of the plants instead of trying to blame the soil.
The types of soil you mention I'm assuming are what is commonly used for houseplant healthy growing.
You haven't said how those clay pots drain, and how you water.
Clay absorbs moisture into itself and is, over time, responsible for why "salts" appear on the inside and outside surfaces. Thus drainage through these pots bottoms is of major importance.
To help a pot drain, something, such as shards of the clay, can be put at the bottom, one to help aleviate the water not sit at the bottom of the soil and the roots, and two, to take up some space to reduce the need for some soil.
Where water is allowed to sit and dry, and be wetted, and dry, without good drainage, it can become, like granite hard.
Plants have sat in the same soil for years and years....and not have to be changed. One can change surface soil if its wished for some reason, but since soil wears out, and there is so little of it, plants need be given fertilizer to replenish nutritive value. As long as a soil can drain its excess away from the roots, plants can go a long time between NEW soils.

You should discuss more how you water your plants, when you water, how often, with what kind of water, what temperatures of the water and where does the water come from.
Since watering habits is the #1 cause of why plants have difficulty, it is the one thing that most discussion is about.
Its the most simple thing to screw up.


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a MI (My Page) on
    Sun, Dec 19, 10 at 15:07

I disagree with a number of points. I don't think clay pots are 'responsible' for salt accumulation in soils. Water can migrate through the permeable sides of clay pots where it evaporates from the pot's surface, leaving behind the soluble salts that were in the water that evaporated. That these salts occur on the outside of the pot has nothing to do with what happens inside the pot. If those salts were still soluble, they would be inside the pot.

Drainage is important in ALL pots, and more so in pots that are impermeable - like plastic, glass, or glazed ceramic. The reason is because when using water-retentive soils, air returns to the whole of the soil volume much more slowly when using pots of these materials. Terra cotta pots allow water vapor and other gasses to pass out of pots and air to enter the soil, both of which hasten the drying of the soil and a speedy return to more favorable aeration.

Shards of clay pots on the bottom of containers might serve to block the drain hole so soil doesn't escape, but it does nothing for drainage. When you use coarse material like pot shards as a 'drainage layer', you simply raise the position of the soggy soil to immediately above the 'drainage layer', which simply reduces the volume of soil available for root colonization. Better, would be to use a soil that drains well enough that there would be no need to provide for additional drainage. Along with the property of 'free drainage' comes added aeration, which is a very large plus for root health/function/metabolism. Roots being the heart of the plant, it also improves the potential for maximizing growth/vitality.

Soil only wears out to the degree that it collapses, structurally. There is such little nutritive value in container soils that we should consider them to have none, and to shoulder the entire responsibility for ensuring plants get all the essential elements they normally take from the soil, in as close to the ratio they actually use as we can provide.

Plants should not be allowed to remain in the same soil for 'years and years' because, along with the compaction comes the condition of being root bound - both having severe negative impact on growth and vitality. To improve the potential for best growth/vitality, plant should be repotted and the soil changed on a regular basis. The fact that I use soils that ensure excellent drainage for many years doesn't stop me from repotting on a regular basis, even though the soil is still perfectly serviceable, to correct root-bound conditions.

I think that proper watering practice is a science unto itself, but I wouldn't say that watering habits are the #1 cause of difficulty, because it is our soil choice that determines our watering habits. Ideally, we should be able to water copiously at every watering so we flush soluble salts from the soil before they accumulate to harmful levels. With compacted and water-retentive soils, we cannot do this, so we're forced to either water in small sips (to avoid the root rot); or, if we do water thoroughly to eliminate accumulating salts, deal with the threat of soggy soil conditions setting the stage for root rot. Our soil choice and accompanying watering habits also largely determine how we can/should fertilize.

There are tricks that you can use to help deal with water-retentive soils and to get the most out of them, and I've covered them in many posts, but it's still far better to use a soil that relieves you from the need to deal with the issues of excess water retention and soluble salts accumulation than it is to try to fix a problem post hoc.

Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Hydrophobic peat moss based soils will compact and become hard.

But there is no reason to think that all potting media will do the same.

Josh


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a MI (My Page) on
    Sun, Dec 19, 10 at 17:13

Very true, Josh. Those who have pressed bark-based soils or other soils with a large inorganic fraction (like the gritty mix) into service see virtually no soil compaction, even when the plant has been in either soil long enough to become horribly root bound.

I think that in saying, "I have noticed that the "all purpose" potting soil is looking really, well, bad. It compacted significantly after just a few waterings, which made me worried about whether the plants' roots are getting enough oxygen. And, it's also gotten really hard, even when moist", the OP has recognized a serious shortcoming of the soil being used that may not be worth trying to fix, thus the links to how to deal with it temporarily until a change can be made with minimal impact to the plant(s).

Photobucket

Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Indeed, Al! Love the Port. afra! ;)

I wish your post had appeared at the time that I was posting...since you covered the bases so well!
I would have formulated my two brief lines, above, quite differently.
Thanks for sharing that pic...it paints a thousand words.


Josh


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Al,

I've searched a number of threads and likely overlooked it, but does your cherrystone have a trade name / ingredient name?

I'm on the hunt again for a better potting mix, a little dissatisfied with the growth I've not been seeing (though it's been a particularly gloomy four weeks of weather and I don't illuminate the plants). I'm going to call the lady who gives us eggs and see where she gets her poultry grit. I'm going to also search all of the area feed stores, but the cherrystone - - I MUST HAVE IT.


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Itty Bitty Gritty Mixie

So far I've got Turface and 1/4" crushed off-white gravel sold as poultry grit. I suppose I could make a mix using both of those and some organic matter, but you'd think that with northwest of here there are mountains made of pumice you could easily get less than truckloads of pumice. You'd be wrong. Thanks for the advice, Al.


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Jan 28, 12 at 14:32

Sec - I'll go look. BTW - I'm glad you found the old thread. I didn't want you to think I was ignoring you on the other thread ..... It's just that it was already soo far off topic I hated to start any cross chatter.

The cherrystone is called just that, and that's what it says on the bag. It's actually quartzite, and a little bit of Fe in the stone is what makes it pink/red. I like it better because of it's appearance. It's mined in MN by New Ulm Quartzite Quarries.

http://www.cherrystonegrit.com/index.html

Remember it's a concept you're trying to implement. If you can find 2 ingredients, one that holds a lot of water (Turface/calcined DE) and one that holds almost no water (like the grit) in the right size, and you combine them with fir bark, you've got it made. The ingredients I use are just the best I've found so far.

If you get rid of the perched water in your soil, I promise your plants will be MUCH happier. I'm serious when I say I water my succulents every 3 days, right along with my other plants, and they do exceptionally well. They may not be as exotic as what you guys grow, I have bonsai to fill that niche, but they ARE healthy. You'll have the whole C&C forum on the stuff within a year.

Best .....

Al



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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Al,

No worries about that post. After mulling it over, I'm going to have to adapt the mix to one that has a higher organic content. The reason is that I don't want to water every 3 days. Although my plants will grow like tropicals in the heat of the summer, I just don't have the time to water that often (up to 3x a week if one's timing is off), so I'll be reading your articles and adjusting accordingly.

Thanks for the information!

Best,

Jeff


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Hey, Jeff!

You know, you can adjust moisture retention without adding organics.
That, I should think, would be safer for your plants during cold northern Winters.


Josh


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

Josh,

A lot of the deciduous plants I have like organics, but they also like drainage - I want to try a Cyphostemma juttae in an almost completely manure / granite chips mix this summer to see what kind of growth I get (I'm thinking outrageously fabulous growth, but I could be all wet) I'll get with that test run.

Thanks to you, too,

jh


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Jan 30, 12 at 13:06

FWIW - I grow hundreds (well, maybe 175) deciduous plants in the gritty mix, and they would prolly grow equally well with NO organic soil fraction. You can get a LOT of water retention out of the gritty mix by increasing the Turface % and decreasing the granite without sacrificing aeration. The only way you're going to get the job done (more water retention) using organic components is to go small ..... then you have the perched water to deal with.

I know it's all about compromise - just didn't want you to miss considering altering the formulation. Your call. ;-)

Best luck!

Oh - note too that I said I water every 3 days because I CAN - not because I have to. I could prolly easily go a couple of days longer, and I'm just using the 1:1:1 ratio.

Later, Al


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

a friend of mines bought a sansiveria plant ( aka - snake plant / mother in law tounge ) and was wondering after buying it from the nursery if it could be planted in the 5-1-1 mix or the grity mix and if the soil that the plant comes with should be taken of ( rinsed - washed ) to use it in the mix or can it be left on ? dont know if taking it off would make any harm or stress on the plant or does with either of the mixes could it make a happy medium transition ?


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RE: Growing medium...leave in bad soil, or repot in gritty mix??

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Feb 4, 12 at 10:53

Yes, please bare-root the plant before transitioning it into a dissimilar soil. If you mix soil types, especially if they are radically different, one part of the soil will always be either too wet or too dry. Sans tolerate being bare-rooted very well - just make sure the plant gets no direct sun for at least 2 weeks after the repot.

Another thing you'll learn, if you stick around, is that our houseplants need regular repotting, which is different than simply potting up into a larger pot. Repotting includes removing the old soil and pruning off many large roots that serve no purpose other than to act as conduits.

Al


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