Reusing potting soil?

mickee311March 23, 2007

I had a decently sized container garden as well as a regular one last year. My containers still have the soil in it. With money being tight on my garden this year, would I be able to reuse the potting soil from my pots from last year? I mean if I took it all out and broke it up? I have many plants that need to be transplanted and would rather not have to go out and buy new bags of dirt.

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I look at soil as soil as that in your reg. garden, so I think it is o.k. to just mix it up add regular fert. as you would in your regular garden thats what I do and with success. Hope you have good luck.

    Bookmark   March 23, 2007 at 12:40PM
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Where economics have a bearing on whether a plant can be bought and reared.....then the plant has to take what its given.

That's not to say though the plant will grow up strong and live a long life.
Much like us humans......if we eat poorly, don't get our needed sleep, lives in poor housing, we will probably have a much shorter lifespan.

I think the same thing can be said for a plant that doesn't get good food, isn't allowed to rest, doesn't grow up where it should, and lives in poor housing.

The soil you bought last year has done its job...last year.
Its worn out...not good for nutritive value.
Plants live in soil...derive their food from the soil, get water from their soil.
Poor soil -- poor plant health. It follows.

I have no wish to suggest you break the bank...but at least, try to give your potting soil from last year, some potting soil from this year. One meal a day might be enough to sustain us....maybe it will do also for a plant.

Chances are the soil in the pot is it must be removed and made better so the roots can take from the soil what it can.
Water can permeate through the soil if it is in a loose state. Drainage then follows.

    Bookmark   March 23, 2007 at 9:11PM
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I usually spread an old shower curtain liner on the ground & dump the soil from a couple of pots on it.
Some of the pots aren't full anyway - since some of the soil that was around the rootballs ended up tossed during the fall clean-up.

Then I mix in some peat moss & perlite & put it back in the pot. The extra gets mixed with the soil from the next pot, and so on - adding peatmoss & perlite as needed.
When I'm done, I mix whatever is left over with the soil in the top of the pots that have perennials.
The soil in those pots gets changed every 2-3 years-usually when it's time to divide them.

I have well over 100 pots. I'd have to take out a 2nd mortgage if I had to buy new soil for them every year!
Plus- my yard is totally bricked - where would I put all that soil anyway?

Here's how it looked last August.
It doesn't look to me like the plants suffered.
I sure have no complaints!

    Bookmark   March 24, 2007 at 6:41PM
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Thanks guys...Before I even saw these responses, I ended up dumping it all out on my back porch, filtering out roots and mixing it with the new stuff I had for this year and repotting. Everything is doing beautifully. I only needed a quick fix for until my raised bed gets built (hopefully this week) and then they will be removed and have a whole nice new big bed full of composted soil and yummy nutrients. Thanks, though!

    Bookmark   April 3, 2007 at 3:00PM
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This message is directed to "Outofspite".

I also have a large number of containers (most very large in size) that are 4 floors up on my rooftop deck. If I replace my soil this year I'm probably looking at 20 of the large bags of potting soil. Can you let me know what the rough percentage of perlite and peat moss that you are adding to a container? I'll be remixing everything (adding some Osmocote, etc.) and plan to fertilize as usual. Thanks for any help you can back thanks you too.

Take care, Pat

    Bookmark   May 9, 2008 at 10:53AM
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For those not wanting to replace soil so often, why not make a potting mix that can last longer? Replacing the peat with pine bark fines will allow you to have a potting mix where the primary ingredient (bark) will last 2-4 times as long as peat before it breaks down enough to significantly impede aeration.

I completely understand the expense of replacing the mix as well as the hassle involved in making the mix which is one reason I don't use peat based mixes anymore. Just seems to me building a longer lasting mix makes sense both time and finance wise.

    Bookmark   May 9, 2008 at 11:35AM
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Well, in my leaner times, I also had to figure out how to stretch out my gardening buck. What worked pretty well for me was to empty out the old dirt, remove the roots and other detritus and soak the best of what was left over in a weak solution of Miracle-Gro water, and allow to drain well in a sunny location for a few days, to sanitize it. I only had to buy a 'fresh' bag or two of potting soil to add to the old stuff. Luckily, I had on hand some nice compost to mix in, and the plants did very well. BUT-if you have a really expensive show plant DON'T welch on the soil. Buy the best you can afford. Good Luck to you.

    Bookmark   May 11, 2008 at 5:06AM
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I keep hearing about pine bark fines and have searched my town, even Wal Mart, and no one has this product. They have pine bark mulch, but in great big chunks. Right now I have asked my True Value hardware store to see if they can order a bag or two. Until I hear from them, where are you buying this?

    Bookmark   May 11, 2008 at 9:55AM
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I have had a hard time locating it in the past as well. Greensmix makes a suitable product called 'Soil Conditioner'. I called the company and asked who in my area retailed it and they said all Wal-Marts have it.

So I went to a few and none had it. I asked for the ordering manager of the garden dept and she called me when she was in. I told her what I wanted and she looked in the computer and said they didn't stock it, but it was something that could be ordered so she ordered 2 pallets.

So, you might ask your Wal-Mart if Greensmix is a brand they can order. In fact just look at all the soils/mulches etc they have outside to see if they carry anything by Greensmix. If they do then they can certainly order the soil conditioner which is what you want.

Generally speaking, just track down the brands others are using and from there call retailers and ask if they sell *anything* by that brand. If they do then they can almost always order the specific product you want.

    Bookmark   May 11, 2008 at 11:02AM
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Justaguy, thank you so much. You have given me the best information ever about this stuff. So many retailers just want to say "sorry we don't stock it" and leave it at that. Very frustrating.

You must have a huge Walmart or a very savvy garden dept. manager for her to order a couple of pallets. Wow. I'm impressed. My Wal Mart says, "Sorry, we just stock what they send us." I'm guessing "they" is Arkansas. Crazy.

Anyway, thank you, I shall look into this now that I am armed with more info. Bless you.

    Bookmark   May 11, 2008 at 11:31AM
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prairiemoon2 z6 MA

I can't find pine bark fines either.

I reuse my potting soil as well. I empty all my pots in the fall and leave the potting soil to sit all winter and be worked on by the elements. In the spring, I mix it together with compost and perlite. 1/3 of each. Seems to work for me.


    Bookmark   May 12, 2008 at 5:47AM
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This is the continuing saga of my trying to find pine bark fines. My Wal Mart told me this morning "Sorry we don't have it, never heard of Greensmix, can't order it, and not all Wal Marts have the same products etc. yammer yammer yammer." I went to Wal Mart and looked at all their bagged products inside and out. Nada. So they're out of the running.

My True Value Hardware store is trying to locate some for me. I called the nursery that supplies my True Value hardware store, Arnold's Nursery in Burlington, Kansas, and they knew what I was talking about, but they package their own bark mix to sell, so they weren't willing to give me info on where to buy the bark itself. The man at the nursery did say that it is composted pine bark. I'm willing to buy a bag if it is not too expensive so my patient daughter is picking up a bag of it for me tomorrow since she lives in the Burlington area and I am 40 miles away. "Do you want a big bag, Mom?" Yup!

Soooooooo, I'm hoping that my True Value store comes through for me on the pine bark fines itself. Man oh man!

I'm trying to be patient. Will let you know more as it develops.

    Bookmark   May 12, 2008 at 11:12AM
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mister_al(zone 7)

I've reused my potting mix for the past couple of years with no problems. I just dump out the mix in a wheelbarrow and add a little alfalfa meal, cornmeal, and some compost. Then I mix it up and put it back in the pot. This has been working for me, so far, but all I'm growing are some peppers and/or tomatoes.


    Bookmark   May 14, 2008 at 12:05AM
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On the topic of reusing potting mixes I really want to chime in. Those of you growing veggies are able to get away with it and so can those of you growing 'pretty flowery stuff' like annual flowers.

The reason you can get away with it, even though it is something far less than ideal, (for the plants) is because you are working with genetic material programmed to push out a ton of growth in a short period of time. As long as the plant can push out roots that fill the entire container things like a perched water table and aeration become less important. Well, not really less important, but the mix itself and it's properties are less important because the genetic traits of the plant are such that the roots will suck up the water in the PWT and they will make their own aeration passages in the potting mix.

When it comes to comparing a spent, heavy mix to a lighter, more airy mix the most (visibly) obvious benefit has been with succulents and perennials.

This isn't to say there haven't been noticeable differences in veggies and flowery annuals, just that the differences are much more subtle and nowhere near as easy to spot.

In the case of the vast rooted, fast growing annuals they appear to grow just fine. Their size and yield hold up well. What I have noticed over the years and this is the primary factor that persuaded me to finally give in and listen to Al is that the fast growing annuals had more trouble later in the season with disease and coping with environmental stress.

If there is any plant I really get passionate about it is the tomato. Kind of odd since I don't really like eating them all that much, but I do love growing them, particularly the heirlooms with no disease resistance whatsoever.

Given the climate and diseases in my area I have yet to find a way to grow disease free tomatos for an entire season. What I have found though is there are ways to delay the plant's eventual death from disease.

This is where I noticed the most difference among annual/genetically hyper plants. Disease tolerance. When I used to grow tomatos in 2-3 year old peat based mixes and even compost heavy mixes I noticed that the diseases wiped out my container plants just as quick as the in ground plants, if not sooner in some cases.

Upon switching to much better aerated mixes this reversed. Today when the inevitable disease season strikes the garden plants succumb much faster than the container plants and there is a definite correlation between the amount of aeration the mix allows and how long the plant survives with the disease.

What I attribute this to is the plant is simply healthier even though the outwardly visible signs are not significant or easily noticed. Disease still strikes due to my choosing to grow plants with absolutely no genetic resistance to the prevalent pathogens, but the speed at which the plants die does vary. I can't think of anything to explain this phenomenon other than the overall health of the plant at the time disease took hold.

    Bookmark   May 14, 2008 at 12:50AM
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where's al?

    Bookmark   May 18, 2008 at 2:46PM
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tapla (mid-MI z5b-6a)

I pretty much agree with what he said. I think that you can get away with using a soil that holds more water than it should if you water judiciously early on & hope for infrequent rain. I think it can and will promote the cyclic death of fine rootage during the period when the soil is saturated. This means that the plant will expend energy to replace lost roots that would normally go into increasing fruit, flower, foliage, and o/a plant mass, but again, it's not something that cannot be dealt with by watering carefully - especially early in the life of the planting.

It's difficult to quantify the effects of a slow soil, because a grower may very well be completely satisfied with the vitality of the planting, and totally unaware of having sacrificed potential vitality and the reduction in fruit/flower/foliage/mass I mentioned earlier.

Unless water is removed from the saturated layer of soil at the bottom of most containers, some root death will occur, beginning with the finest roots first. This becomes less of a problem as the planting matures and roots extend throughout the entire soil mass, and o/a plant mass increases, but it still affects mature plantings unless the perched water in the saturated soil is quickly replaced by air.

I think there are at least three ways to look at the idea of soil choice. The first group I see is one in which the members come armed with very little in the way of knowledge, and are often completely uneducated about soils, blissfully unaware of what makes a good/bad soil & just use whatever is least expensive, most convenient, readily available ...... you get the idea, and hope for the best.

A second group of growers are armed with some knowledge, but are willing to knowingly sacrifice some plant vitality and be satisfied with the results for the sake of the convenience of being able to not bother making their own soil or even amend a bagged soil, and not having to water as frequently as a faster, more highly aerated soil dictates. I should probably back-track for a second. It's not necessary that this group willingly sacrifices some plant vitality. In many cases, life styles and schedules dictate it as a necessity. Most would probably balk at being at work for 12 hours/day & having to rush home every day to save the wilting. ;o) Some simply do not have the time it takes to insure optimum results from the growing effort.

It's not our job to tell you what to do. ;o) We can only offer advice based on our own experience and what other often useless knowledge we have stored in memory. We can, however, tell you what is likely to happen if you do a, b, c, . . . or a combination of any of the above. Then, it's up to you to decide how you'd like to proceed.

I said three, right? The third group is one that wants to squeeze a little more out of their growing experience, and are willing to pay their dues in the way of seeking more information and will go the extra mile when it comes to the growing experience. I really like almost every person on this forum, but I think I naturally tend to gravitate toward and spend the most time with groups 1 & 3. I love to help people learn when I can, I absolutely love the enthusiasm that group 3 brings to the table, and like me, both groups are generally very 'results oriented'.

That said, I never assign anyone to a group - never even thought about it until today, and the lines between the groups are extremely blurred. I only created the idea to illustrate a point. ;o)


    Bookmark   May 18, 2008 at 5:21PM
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Hi, I worry about bugs and diseases overwintering in the soil.I have a very bad problem with spider mites on my patio.wont the old soil carry the bugs to next year?

    Bookmark   September 12, 2011 at 5:36PM
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