So now that summer is just about gone, how did everyone's potting and plants do this year?

Good results to report here. I'm one of those who re-uses the pots often without doing anything. I take the old root balls out in the spring (with the dirt they have on them,) 'stir' it up a bit, refill with plants, and replace as much soil as necessary. If the soil really doesn't look good, I will dump it into the new soil mix, incorporate it, and keep going from there. Everything is doing well this year, with some overwatering exceptions due to all the rain we've had (11 inches in Aug.!)

I do exactly what memyselfandi does. Just add more the next year as necessary.
Gayle

Hello,
I'm new at this board, now that the season has come to a end, I'm searching around for info for next spring. Love the site, looks like alot of good information. My question is, what can I do with bags of indoor potting soil? They have been left outside for the summer months. Can I use them next season in my garden? Should I just store them in the shed for the winter. Please help, I dont want to get rid of good bag of soil.

Thanks

Hi Springchild - this is the frugal forum - we don't throw out haha! If you have room in your shed, I would store them there. If they are already opened, a few weed seeds may have blown in but no big deal. I never heard of potting soil having a shelf life - you can plant with it next year! If you haven't been over to the Winter Sowing board - jump on over. You may find some use for it this winter :).

Thanks Mikee2, I will store them in my shed. Should I add anything to the soil, before using it. I know that it is indoor soil, which is different than outdoor soil. Should I add peat moss to it or compost?
Thanks

You can add either fertilizer or compost. Fertilizer tends to build up salts in the soil, so compost is a better choice.

Vicki

If you're one of those people who like to "cook" your soil, you can put it in an aluminum roasting pan and cook it on your grill outside. Saves the odor in the house.

(That might be a good way to get a night out! What's for dinner? Stinky potting soil.)

Barbara

I have had luck with leaving used soil outside for the winter, covered. The freezing temperatures takes care of any disease. I reuse everything!!
TrowelGal

You can also toss boiling water on the potting soil to kill most weed seeds. It doesn't stink like cooking it does.

I just buy a new 20 kilo bag of potting mix for $3.25
it's cheap enough,and I mix the old mix into new garden beds that I make, or add it on top of existing beds,to condition the soil.
The worms mix it in for me.

Get a big foil roasting pan and sterilize the soil in the bbq grill outside.

Kathy in illinois

If my older soil is clear of roots and weeds I just dry it out and mix it with some new compost and a bit of soil and a touch of coffee grounds. I don't know why... I've always figured 'dirt is dirt'. As long as I take care of my plantings there shouldn't be any problem. Any of my 'crappy' used soil recycles into the flower beds. Jim

"it is indoor soil, which is different than outdoor soil." Love it!! I have a bad case of invasive indoor soil, it multiplies rapidly. You should see my vacuum cleaner bag. I think it likes pets and children.

Whoa, if you post at midnight, it reads as 0:00.

I've been following this thread for some time with a great deal of interest.
I'd like to used compost for starting seeds, but want it to be sterilized. Also, I want to sift it pretty fine because a lot of the seeds I want to plant are very small.
I was thinking of sifting the amount I needed, then using the microwave to sterilize it.
Has anyone tried this? It seems to me it ought to work and be less hassle than the boiling water or baking in the oven.

I like to combine old (worn out?) dirt from potted plants with compost, stick it in large, black leaf bags (which I re-use and re-use until they fall apart) and stick them out where they will sit and 'bake' in the sun for a couple of weeks...

So far *knock on wood* this has managed to 'bake' all the weed seeds to death and combined with the potted plant dirt, which usually has sand/vermiculite/peat makes a really nice additive to my garden soil....

I microwave used potting soil..... I sift it first through an old deep fry strainer, dampen it slightly, fill a large Corningware or Pyrex container, cover with saran and then microwave for about 5 minutes. I let the soil cool with the saran cover still intact. Lotsa steam to sterilize the soil and no odors....
AdaO

Ada--that's what I did this year. Put some in a paper bag and zapped it for 10 minutes. No fuss, no muss, and no nasty smell.

Really interesting reading here. If, you do it in the oven do you wet the soil? What tempature for the oven. Also for a product like miracle potting soil is it sterilized? Normally I mix and reuse soil with new, but have a batch of gnats and looking for moisquito dunks now. I am rethinking what to do about my soil in future. Thanks

I always re-use my potting soil, have a huge pot bigger than a washtub I put any excess potting soil in & add dried leaves to it when I have them.
It has a lot of earh worms in it, always try to add a few to a new pot to work the soil for me, all my plants are thriving. I wouldn't want to use boiling water or cook the soil & hurt my earth worms!

In the thread several speak about treating the soil, removing the rootball, etc

Do you do this in the fall or the following spring?

if the potting soil has pathogens throw it out. otherwise sterilization is eliminating all the beneficial edaphon.

Healthy soil is alive ~ don't kill it!

My first attempt at seed starting was a total bust, and now I'm left with a tray of starter mix. There are seeds in there (though obviously they're not going to sprout), and I noticed a couple of gnats, but is there ANYTHING useful I can do with it? Thanks.

I'm also wondering about timing - when my tomatoes and peppers are done next month, should I amend the soil then? Should I store it in my shed? Or just leave the plants in there til they give up the ghost and work on the soil next spring? AHH? Sorry to be so dense, but this is new to me. Thanks in advance for your tips. :-)

I've been reading everyones comments on to reuse soil, but do I keep it in the pots in the garage over the winter?
Then in the spring mix it up with new soil and plant as usual? Can I put it all in a big container in the garage and put a lid on/off? I have a liitle green (not much) growth on top of two containers. Do I leave it or take off the top layer? I'm also moving south next year. so I was maybe thinking on taking the soil with me. Or is that a bad Idea? I've got approx. 30 large containers and I'd hate to think of what that would cost to fill them all up again.
Chere

I dump the pot contents into the compost bin at the end of the season to "renew" it. Then in the Spring I go to a couple large chain stores just before they close and buy broken bags of expensive potting mix for $1 a bag. I am still re-using my old potting mix in a way because it all comes out of the compost bin eventually and into some gardening project.

First I dump potting soil from starts that don't make it back into the mix I use for potting soil (shredded peat and the cheapest soil I can find ($1 for top soil HD ... just want something sandy .. I save compost for veggies ... never enough).
If you want to cook soil you can place soil in a flat container, cover with glass or a heavy plastic and place in full sun. This is known as solarization (or solarizing soil)and I do this on a larger scale to kill nematodes when breaking new ground. In short order you will "cook" anything living in the soil. And its FREE!!
Mike

I have a lg deep freeze. It seem that by Feb it's almost ementy. I put the used potting soil from last summer in a lg old soup pot & put it in the freezer for a week. I figure at 30 deg will kill most anything. When I go to plant seeds in it I use Ozmacote fertalizer. I've never had any problems!

I have always reused until this year Most of it was new. I lost a bunch of seedlings to damping off. didn't even think about it mixed the soil back, lost more so I spent the day boiling soil. And my Grandaughter is sick of bleaching pots!

I can't imagine not reusing any kind of soil and I certainly can't imagine baking or broiling it or zapping it...dirt of any kind is precious in the Texas Hill country and I save every smidgeon die ewyaw...but without all the cooking...

Hi there, Last Year I had problems with plants (tomato, pepper, a few peas) in pots on my apartment balcony. They started fine, and produced a little bit. But they were definately affected by some sort of disease. I'm planning to try again this year. I'll wash the pots and stuff with some sort of bleach wash. Can I reuse the soil if I nuke it in the microwave. Or would it be better to throw it out and try new stuff.

Thanks... Mike, Ottawa, Canada, Mar'07

The problem with reusing potting soil isn't diseases, it's drainage. Diseases usually won't be a concern in a well drained, well aerated soil. Drainage can get to be an issue quickly when a potting soil starts to break down. Peat and compost based soils will break down quickly, usually in the first year.

Any frugal gardener should be mixing their own container soil. The commercial stuff is overpriced and of poor quality. Use pine bark as the base, with perlite added for drainage. A small amount of peat can be used to increase water retention. If you use really coarse bark and perlite the soil mix will hold up for more than one year for most applications.

Seed starting is a separate issue--always use a fresh, sterile seed starting mix. Losing seedlings to bad soil is certainly not frugal.

Check the container forum for much more information...

Jason

Here is a link that might be useful: Container Soils

Yuppity. I mixed potting soil myself last year and made mounds and mounds and MOUNDS of it for far less than what it would have cost to buy.

After it's broken down enough that I'm concerned about its drainage in containers, it's still an excellent amendment for my garden beds.

Kristin

Can someone explain the boiling water technique a little more clearly? Is it that you don't use much water and let the soil absorb it or do you need to drain it?

Hopefully we are more enlightened in this decade.

Boiling soil: I have a couple of 5-gallon buckets with lids (ask anywhere that serves pickles regularly to save buckets & lids; it's not uncommon to offer some cash, but not always necessary, especially if you can establish a repoire with the manager) that I use for "boiling soil."

It's as simple as putting the offending soil into the bucket, no drain holes, no prewetting necessary, although if it's really wet maybe let it dry out in the sun for a bit before boiling. I put my full kettle on to boil, and after it whistles, pour the entire contents over the soil. Cover, and leave overnight; the steam will probably do as much of the work as the boiling water itself. If you add too much water, you run the risk of overwetting the soil and causing the components to separate--all the sand ends up on the bottom, and the pretty perlite flakes all on top with the twigs and bark pieces from any compost in the mix. BAD!! Now, you have to 1) let the stuff dry out a bit (in which case new yuckies can get back in, depending on where you do this), and 2) mix the whole thing back up.

As far as using your deep freeze to "sterilize" soil, I've got some news for you: head on over to the wintersowing forum and you will realize in short order that MOST seeds can survive freezing temps, as can most diseases & fungal spores. Bugs won't stand a chance, though, so if you've got some buggy soil, this is a great way to kill them off and then leave them in there--they'll be great addition of protein to your soil.

I generally will do "mini boils" on my wintersowing containers if they're tough enough to take the heat. Otherwise, I have been known to do the boil in the microwave in a glass dish with a plate on top; again, you need to let it sit so the steam can heat through, especially the parts that didn't get directly touched by the boiling water. On that note, I use almost nothing but recylcled soil for my wintersowing, and I wintersow almost everything except for pepper and some bedding flower starts that I want to be bigger before planting out time. For those, I have great success with peat pots unless they don't like acidic soil (peat can also hold too much water and cause damping off, but the capsaicin in peppers prevents this from being a problem), in which case I will use some sterile potting mix--keeping watch for the bargains as have been mentioned above.

By the way, I had some old peat pellets that smelled musty, so I put them into a tub with some water, and nuked the whole thing--they expand very quickly when heated with their water! Beware not to let this concoction boil, however; the peat will break down and your resulting peat ball will have lost half of its contents. Ask me how I learned THAT one!!

Here's a question: anyone reuse peat pots that didn't take? I would think nuking them would make them reusable.

I asked a greenhouse grower why potting soil wasn't generally reused and his answer was that the peat refuses to take up water. Potting soil comes with a "wetting agent" that can degrade or be washed out over time. Therefore it might help to add more of this wetting agent and water it in. Earth Juice sells a product called "Earth Juice Assist".

Another concern is the lime. Potting soil contains dolomite lime which keeps the acidic peat in check as it breaks down. It might be helpful to add some lime to the soil before reuse as well.

Another concern is regarding drainage as the previous poster pointed out. As the peat breaks down it will be more likely to "pack" which can drown roots in their search for air. Adding compost and leaves can exacerbate this problem.

One strange problem I have been running into when reusing potting soil is causing some plants to lose vigor, turn pale yellow and droopy. I do not think it is due to compaction or poor drainage. My best guess is that it is due to nutrient or salt buildup? I am using liquid organic fertilizers but they are very cheap so for all I know they may actually be chemical ferts.

I am growing vegetables so I have been watering with R/O water. Because of this, a flush becomes an expensive and bothersome proposition. Maybe I'll have to flush with "24 hour" tap water and see if that helps the situation.

Just curious. If old peat is such a problem, why is it used in sq ft gardening. Once you have mixed the first batch of "soil' all you need to add going forward is more compost. If you are planting in this old peat year after year, why isn't it causing a problem like you described?

reuse of soil is a good way to garden on a budget. in most casual garden situations you can use the same soil without doing anything more than a fresh water rinse through the soil. do not use boiling water, bleach, or other chemicals that will sterilize the soil and make it dead. even dry soil is actually very much alive with micro-organisms like microrizal fungii and beneficial bacteria. without these things your plants will not grow, the soil you buy contains thousands of these put there by the companies making it (which is why people have to bring their soil back to life by adding purchased soil to it after killing it with boiling water =0 ).

My tips for possible soil reuse problems (container plant methods):

one of the most common problems you will face with reused soil is nutrient salt buildup. this is easily avoided by having proper drainage, as well as flushing your plants with plain water about once a year or season depending on type. (preferably with as little chlorine in the water as possible, it will kill beneficial organisms in the soil)

The other common problem is soil pH balance. I recommend you buy a soil pH test kit about once a year or season and test your soil when you are preparing to reuse it to verify that it is within range for the plant/s you want to grow with it. If the soil is not within it's proper pH range, you can add dry supplements or chemical adjusters to modify the pH to be within acceptable levels.

Another issue you may face is disease. If a plant is lost to root rot or similar soil based disease, you can use the boiling water technique to sterilize the soil. then either add some fresh soil, or you can purchase a packet of microrizal fungii and bacteria from the garden shop to add into the sterilized soil. You should also combine the fungii packet with some dry animal and plant nutrients to provide a sufficient food source to re-colonize your soil with micro organisms.
(note: a healthy compost pile can contain the right bacteria, fungii, and nutrients to re vitalize sterile soil. however there are a lot of common food items that should not be put into a compost pile that is intended to be used in a garden. alos, the compost should not be too "hot" when added. look up composting for more info)

hope this helped, and have fun playing in the dirt =)

I know it's been nearly a year since this thread was last posted on, but I want to thank everyone for the good information contained therein. And particular thanks to DrJonez for pointing out some very good reasons for NOT heat sterilizing or pouring boiling water over soil (namely soil is a living ecosystem, you end up killing as many good things as bad with heat).

I liked the advice about flushing the soil with regular temp water. But I live on the 2nd floor, I don't have easy access to a hose, and I wouldn't want to send tons of water to my downstairs neighbor's (actually, landlord's) patio. I wonder, if you've had a wet spring, will the containers be sufficiently flushed? or almost sufficiently flushed?

Anybody microwave soil for reuse?

we used to dump all the containers out and stir up the soil, add a little new stuff and plant them back up again. but for the past few years we dont even dump out the containers anymore (the big ones) we just stir up all the soil, plant and fertilize. havent had any problems at all, and its so much easier than dumping it all out and mixing up then repotting!

i do like the idea of testing the ph, ive never done that. i will have to do a search on plants salts and their build-up. we get tons of snow and rain so i think the pots get a good soaking and draining anyway. oh - and only rainwater to water them.

Y'all I've never heard of cooking the soil. My Mom always told me to spread it out in the sun a few days n that kills any bacteria. I guess it works. I have beautiful Pansies at the moment!

If you are concerned about soil diseases, you might try using a sun-oven to sterilize your soil. It is easy to make. Here is an example http://www.instructables.com/id/Best-Solar-Oven/.

I reuse every year. My method may seem like overkill to many but I get amazing results. Been doing this method for over 5 years.

https://youtu.be/sodNoXayUKA

There is so much "off" with that video, I hardly know where to start!!

The reason it is suggested to use fresh potting soil each season is less to do with disease issues than it is with the deterioration of the soil itself. Most potting soils - soil-less mixes - are peat or coir based and with very small particle size. Some also have compost as part of their composition. These are all forms of organic matter and will continue to breakdown and decompose and compress. As a result, pore spaces between the particles are also tiny and the watering frequency required for container growing tends to further compress and compact the mix, reducing aeration and therefore drainage. Bark based or gritty mixes - using a more textural and durable base - are less inclined to compaction and can hold up longer. A peat based mix is pretty much useless by the end of the growing season.

At the very least, the soil needs to be refreshed. And that is done by adding new, unused potting soil at 50% by volume. Adding perlite (not 'perilite') or pumice or grit is not a bad idea as well - they will also help to establish new pore spaces and maintain aeration/reduce compaction.

As to the use of granular organics in a potting mix........not at all an efficient or effective approach with container gardening. Dry organics require the activities of soil organisms to break them down into a plant usable form in a process known as mineralization. Without sufficiently high populations of these microorganisms, the product just sits in the soil, unavailable to the plants and unused. And any population of soil organisms in just about any potting soils will be minimal...........because there is no 'real' soil (aka dirt) in the mix and peat and coir do not support this sort of biological life. No bugs = unprocessed and unused, unavailable organic fertilizers.

It is very difficult to be completely organic and yet still grow successfully in containers - the two methodologies tend to work at cross purposes. You can get by with using liquid or water soluble organic fertilizers but these are few and far between. Organic fertilizers just do not lend themselves well to this method of production. And by definition they are slow release, often not offering up appropriate nutrients (provided there is the biological element present to deliver them at all) until too late in the season to be of value.

It boils down to what you are willing to accept with regards to your container plant growth. Acceptable but less than stellar performance or lush, healthy and bountiful crops. One will come with reusing what is likely an inferior soil mix to begin with and augmenting with a mostly unusable fertilizer regime or start with a high quality, durable potting mix and fertilize with an appropriate liquid or water soluble fertilizer......probably not one that is organic in its derivation.

You may not agree with my method and that is fine. But I have been using it for well over 5 years and it works!!! I have lush crops and a plentiful harvest!!

You may have your methods that work and that is great. There is never just one method for gardening.

Until you try a method that someone suggests there is no reason to be critical until you try.

I am critical because you seem to imply from your video that dry organics are an efficient means of fertilizing containers. They are not. This is not my opinion but a scientifically established fact of gardening life. It also implies that you do not understand how organic fertilizers work, which I find to be even more of a concern, given your screen name and your advocation of this methodology.

btw, I am not just your average hobby gardener but a degreed professional horticulturist that makes a living advising gardeners and teaching about soils, fertilizers and container gardening. So I do not need to "try" an ineffective and inefficient methodology to know that it will not work.......or not work to the same extent that more tried and true, scientifically established methods will.

btw, the "5 years and it works!" claim is anecdotal at best. And works to what degree of success or optimization?

Using this method I have never had a dying or diseased plant. Have had plentiful harvests up until frost. Never had blossom end rot. My veggies are tasty and delicious. No complaints. My plants never show a sign of any nutrient deffiency. And I never add additional fertilizers.

Science is great and all but my method works!!