Re-using container mix

Ugh. I was all set to put my tomato seedlings in their "forever home " this weekend, but find myself struggling to decide how much of last season’s container mix to re-use.

All of my containers have “sub-irrigation reservoirs”. 16 are “Earthbox”, which have pretty detailed instructions, but I don’t recall specifics about how to know if the mix is too broken down, not draining right, or too acidic. They say it’s fine to re-use mix you grew tomatoes in, and say no “compost”.

I found this;

" Q. An excellent question, and one that deserves an intelligent discussion. But instead of that, I’ll tell you what I do with mine."

Also, last year all of my tomatoes got some kind of problem that seemed to be a foliage or nutritional (not wilt), that I have never seen in almost 25 years, or at least not affecting all of my plants.

Finally, is there a temporary measure I can take to reduce the stress on about 20 seedlings that are drying out and wilting daily? Right now I have them submerged in the soil of a large container.

I have a bale of peat moss , vermiculite, perlite, mycrocizze ( something like that), and maybe some “garden lime” to mix my own or refresh. I also have bricks of coir coconut fiber.

I don’t usually reuse compost but, in spring last year, it was either that or have no compost at all, as the garden centres were closed. I had a little bit of fresh, which I mixed with the previous years compost, some granular fertiliser and ordinary garden soil. For the first time, I also got into a proper routine for a weekly feeding the plants in containers. It all worked well. I was growing ornamentals, not edibles.

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For big beds, I can’t change the soil every year, too much work and costs a lot. I add compose, fertilizer and new soil, never have big problems.

For soil in smaller pots that have grown veggies, will trash the root balls, the soil will go to other non edible plants as they are less demanding in nutrients.


In theory, one needs to do crop rotation, you can’t plant the same family of vegetables year after year in the same place, there will be diseases and yield will be lower.


Here’s an oldie but goodie from gardenweb.

The OP ends with “I have seen advice that some highly organic soils are productive for up to 5 years. I disagree. Even if you were to substitute fir bark for pine bark in this recipe (and this recipe will far outlast any peat based soil) you should only expect a maximum of three years life before a repot is in order. Usually perennials, including trees (they’re perennials too, you know ;o)) should be repotted more frequently to insure vigor closer to genetic potential. If a soil is desired that will retain structure for long periods, we need to look to inorganic amendments. Some examples are crushed granite, pea stone, coarse sand (no smaller than BB size in containers, please), Haydite, lava rock, Turface or Schultz soil conditioner.”

A subsequent post reads "There is wide disagreement on this point, but I never reuse it, turning it into the garden or on the compost pile instead. Others reuse it.

If you use the search words “tapla reuse” on this forum’s search function, without the quotation marks, you’ll be able to read other’s comments about reusing container soils. Here is my opinion:

In my estimation, the only case to be made for reusing container soils is one of economics, and you’ll never find me argue against making that decision. If you can’t afford, you can’t afford it. That said and setting economics aside, you might decide to reuse soil for reasons other than economical. Perhaps the effort involved with acquiring (or making your own) soil is something you might not wish to go through or be bothered with.
In any case, it would be difficult to show that soils in a more advanced state of structural collapse can somehow be preferred to a soil that can be counted on to maintain its structure for the entire growth cycle. So, if the economic aspect is set aside, at some point you must decide that “my used soil is good enough” and that you’re willing to accept whatever the results of that decision are.

All soils are not created equal. The soils I grow in are usually pine bark based & collapse structurally at a much slower rate that peat based soils, yet I usually choose to turn them into the garden or give them over to a compost pile where they serve a better purpose than as a container soil after a year of service. Some plantings (like woody materials and some perennials) do pretty well the second year in the same bark-based soil, and with careful watering, I’m usually able to get them through a third year w/o root issues.".

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In the UK, it’s always recommended for perennial planting that you use a loam based compost (such as John Innes #3). The recommendation continues that when a perennial plant (herbaceous, shrub or tree) cannot be repotted, then you scrape off the top 50mm or so of compost and replace it annually. I’ve followed that advice for a long time and have shrubs that have been in the same pot for well over ten years and continue to perform well. I also tend to mix a handful of granular fertiliser through the new 50mm.

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Not sure how this thread got by me. I like to bring Spring in with fresh Miracle Gro potting mix. A bit pricey but gets my annual flowers off to a good start and I don’t have to feed until after month 5.

Usually I put the discards in a dirt/play pile for my grandson, but this year I dumped half the dirt in a new area, put down gladiolus bulbs, covered with a thin layer of MG and dumped the rest of the dirt on top. 15 of 20 have already broken ground and well on their way. So I don’t feel like I wasted money.

My husband otoh just tills up his vegetable garden, fertilizes, rotates crops and unless we have excessive rain or insect problem does just fine . Kinda six of one half a dozen of the other.:slightly_smiling_face:


Shout out to @Miss_belle, so you don’t miss it.

Anybody have thoughts about this article?

Microgardener-Re-using old potting mix.

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