imafan26
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Reusing soil in containers

I have been having more problems finding soil for my containers. I can make my own, but even peat moss and perlite have become hot commodities. Many of the ag suppliers are not selling retail or require $100-$300 as a minimum purchase.

I usually don't reuse potting soil in containers. It is usually recycled into my yard or garden, but now I have to reuse it.

It took me many disappointing plantings to realize that I did not replace nearly as much fertilizer than I needed. I had assumed I would have some left overs so I put a lot less. Bad mistake. I got puny and sometimes not productive plants. I found I had to put the same amount of fertilizer as a new planting.

I usually remove all of the soil, take out the roots and rinse out the pot and make sure the drain holes are clear. I put the soil back, but I find that even when it drained freely initially, after I put the old soil back in, the water sat on top of the pot for a long time unless I used as stick to drill new channels for the water to pass through. It was one of the things I did not expect to find that well drained pots would have drainage issues if the soil was reused.

The other thing I discovered was that growth was much better if I had at least 40%-50% of the soil be new potting soil with the older soil on the bottom. Plants just do better in the new soil. It did not matter that the mix was the same between the old and the new.

Do you have problems or successful recipes for reusing potting soil?

P.S. I don't reuse soil if the plant had disease issues.

ElizabethA
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I have always reused my potting soil for flowers on my back porch. They seem to do fine. I always put a liquid fertilizer on my plants every few months and they seem to love that!

imafan26
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I have a lot of weed in the containers so they keep popping up. I also had fertility issues since I could never figure out how much fertilizer would be left from the previous plants.

I did what was recommended and used old potting mix on the bottom half and used new on the top. That works until the plant roots get to the bottom of the pot. There is usually a faster decline in the plants.

I have tried something new this time. I figured out that I actually don't have much fertilizer left in the pots at all so I put the full amount of starter fertilizer, but if I only put it in the new potting mix, it did not stop the early decline of the plant. This time I added fertilizer and lime to the bottom of the pots where the old mix was, and also added the starter to the new mix on top. So far, it is working out much better. The plants look healthier and more vigorous longer. I'll have to wait and see how long it lasts.

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digitS'
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Imafan, there are only a few pots in the yard with annuals. My mix for them and the perennials may change my perspective on potting mix. It is reused. Plant starts for later transplanting into the garden - that soil comes out of a bag from the garden center.

Since nearly all of a large garden's transplants are from seeds in common containers with those seedlings "up-potted" PLUS the perennials getting fresh soil each year -- there always seems to be a lot of soil mix to be dumped in my compost. Partly, it's my imagination :D.

The plants in the distant garden are just turned under each year. What is in my compost here at home amounts to bucket after bucket of kitchen peelings. However, those decompose - down to the equivalent of dust, if they have long enough. Peat and perlite lingers.

Annuals in pots for the yard have 100% compost. I have to watch the soil level in my potted tomato plants at the foot of the back steps as it settles and needs topped off through the summer. Same with the annual petunia and pansy pots in the front yard. Perennials have been getting purchased peat and perlite about 50:50 with their compost. Bagged organic fertilizer is also added for them.

Long story short: I don't worry about re-using potting soil. Weeds? My compost never runs very hot so the "weeds" in the pots are things like tomato and squash seeds that sprout. Yes, they will look bad if I leave them. The plants grow just fine in our 5 month growing season. Most of the perennials are on the floor of the greenhouse right now. I'll have to cover them when it is too cold. There won't be heat on in there until mid-March.

Steve

imafan26
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I used to use the old potting soil in the gardens and around the yard. I did not reuse potting soil very much. The weeds are the most visible problem, but there is also the problem of nematodes, bacterial and fungal disease, and I have recently figured out that I have some soil mealy bugs in the pots. Now, I know why some plants are not doing well in some of the pots. I saw the white fluff in the soil and on the pots before but did not recognize them as soil mealy bugs. Now, I have to be more careful and dump that soil and bleach those pots. Soil mealy bugs destroy plants slowly over time and are difficult to control. Nematodes are prevalent here. It is one of the reasons why I grow most tomatoes in pots and ginger has to be grown in clean soil as they do not tolerate nematodes at all. I have bindweed, nut sedge, baby's tears, California grass and a lot of spurges. If you leave a node in the soil, they survive. Winter solves a lot of your weed issues. Weeds here actually flourish with any rain. That is why I use a lot of Round Up. I could not keep up otherwise. The wild bitter melon, Fukien ti, and weedy trees are also hard to kill with Round Up because it does not work well on shiny leaves. I have to use triclopyr to kill trees and it is much more toxic than Round Up.

PaulF
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I remember a few years ago a conversation about re-using potting soil and several said the soil needed to be sterilzed before use. They did the sterilization by baking the soil in an oven to kill all the pathogens and weed seeds.

I would think to get the soilless mix ready for containers some kind of general fertilizer would need to be mixed in before using the soil again. Seems like a lot of trouble. Will soilless mix really hard to find or is it just the time of year? I am glad we have several big bags left over from last year.

imafan26
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All garden supplies from seeds, some tools, soils (compost, potting mix, perlite, peat moss), and even some plants have been hard to find all since about April. More people have taken up gardening as a past time while they have been stuck at home during lockdown and more people are interested in growing their own food. During the summer, soil amendments , except for rubber mulch would arrive on Thursday and be gone before the week end was out. The seed racks have been refilled 4 times and online seed companies had suspended sales for a time and some of them are still out of stock on some items.

I usually make my own soil mix, but I did not want to use a lot of soil mix in the larger pots since I did not know when I would be able to get more. I have peat moss, but perlite is harder to get. The supply has gotten better now that the holidays are here and people are busy doing Christmas shopping and putting up decorations so the soil supply is better. The tools are still harder to get especially since the big box stores gut their garden section and it is filled with Christmas items now.

I cannot find French or lemon Thyme, but I was lucky they were delivering angelonia the day I was there. I could not find white false heather, but it is not always easy to find it at any time.

I cooked soil in the oven once, I will not do that again, it stank. I had been taking my soil to the garden and cooking it in the soil sterilizer, but it gets mixed with the other garden soils. I don't use merit in my pots, but they do, so I could only use that soil for ornamentals. Depending on how wet and hot it was when they take it out, it can have a lot of fungi.

I have been just adding it to my garden and yard, I have weeds everywhere so it really does not matter. Soil that had issues with virus or bacterial diseases, and now the soil mealy bugs has to be thrown away. It is hard to do that in quantity. the other soils even though they do have weeds, it is the weeds I already have in the yard so it does not matter, but it does make more weeds to have to kill later.

Since there is no winter, most plants will live over and so will bugs and disease. the soil never freezes, so soil pathogens don't die out either.



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