I realize that using new potting soil or mixes is the ideal practice but I do wonder if there are folks out there who reuse potting soil. All of my first pottings are done with Schultz Plus or a medium I make myself (from packaged potting soil, Perlite, and spag peat), and all of my plants are from seeds I sow myself. So if the plants are from seeds and the mix is all "clean" to begin with, what are the risks in reusing the same soil in much larger containers (mixing in new as well) as I pot upward for pot-hog plants like cucumbers or Dahlias?
I do realize that the major concern is spreading disease, but I also wonder if this is a small risk or a large one. As i said, the origins of the plants and soil are the same in either case. Also, I'm supposing that replacing depleted nutrients with fertilizers is no different than it would be when a newer soil becomes depleted.
I've already done this with some seedlings so I am asking after the fact, but I am very curious if other people start from scratch as a precaution or if there are others reasons that are not so obvious to me.
Reusing potting mixes
Good question. I've reused soil in the past but the more I learn the more I think I'll give them a fresh mix. Tapla always has good advice on these things.
My perspective and why I hold it:
If the decision to reuse container soils is an economic one, who can disagree with the decision? If you aren't concerned about expense and are willing to go to some minimal extra effort to build a good soil, that is what I would elect to do.
Here's why: Container gardeners need to direct primary focus to insuring that the soil they are using will remain able to provide adequate air to roots for the expected life of the planting. Along with the ability of the soil to hold ample air, comes good gas exchange and drainage for rootage. All the other major cultural variables affecting growth are easily manipulated. Water, nutrients, sunlight, and to some degree, temperature can all be controlled easily. Aeration cannot and its consideration is as important as water and light to plant vitality.
The breakdown or collapse of soil structure occurs at an exponential rate. If we imagine the usable life of a peat based container soil from a bag, it deteriorates from a reasonably good soil when fresh to unusable after 2 years. It's not unreasonable to expect the soil to lose at least 20-25% of its air holding ability by the end of the first growing season. In the first half of the second growing season, it will lose about another 25% of its air holding ability and in the second half of the second year, near total collapse is likely as the remaining 50% is lost. Though this is an example of an imaginary soil, it is very close to what actually occurs. Another way of saying it is: Even though a soil might be performing acceptably at the end of the first growing season, you should expect a rapidly accelerating collapse in the subsequent year.
So, if you use a soil for 1 year and mix it 50/50 with a fresh, similar soil, 50% of the soil will have totally collapsed by the end of the growing season, and the other 50% will have lost about 25% of its ability to hold air. If a soil is not holding enough air, it's holding too much water. Water and air retention vary inversely in soils and when one increases, the other decreases. When soils hold too much water, you have to hope that the plant will use enough water or that enough water evaporates to prevent root rot issues and even minor cases of over-potting can mean terminal misfortune.
Additional considerations are possible carry-over of fungal spores, the possibility/probability of insects in various stages (eggs, larvae, etc) and build-up of carbonate precipitates from your watering water. A slow soil will also have accumulated fertilizer salts and possibly insecticides that you may have applied and forgotten about last season.
I suggest that container soils be turned into the compost pile or garden and fresh soil used in its place unless monetary considerations prohibit.
Al
I will follow your advice, Al.
For several years, I've re-cycled some of the old potting mix into the containers that sit in my raised bog area, since I don't want or need fertilizers leaching into the pond water (Yeah, I know I could just get some mix without fertilizer, but I never think to buy it when I'm in town, and the mood to dig in the dirt usually strikes when I'm not willing to make a trip to town first, lol.)
When I empty those containers out, the mix goes into a bare spot in the vegetable garden, or to the compost pile, along with any other of last year's container mix that I tossed out.
Well I feel smarter. That was always a question in the back of my mind. I have re-used the potting soil. But I am going to go buy new bags today.
So I shouldn't buy bags and store them for next year? Shoot.
I have always reused soil as well. This is the first year I have done gardening to this degre..but in the past with houseplants, some veggies outside, etc..I have always reused and mixed. Heck, I have spent over $150 in soil this year alone...no way I am doing that yearly and I certainly cannot see past generations doing that as well.
That's alot of soil! I can't do that either. So it is new soil when I can, and old the rest of the time.
Tell me GiddyMood, what are you planting that you bought that much soil?
The house we took has a lot of earth issues...very hard soil, crab grass, Bermuda, very invasive stuff, etc so we decided to do most of everything in barrels. We bought about 10 wine / wiskey barrels and cut them in half. I have bought some amendments to improve the soil in some areas of the yard and planter boxes that were already here as well.. and then the rest of the soil was for the potted plants and such.
Well, even a 3 cubic bag of decent soil is about $4.00 and it takes 3-4 to fill each half barrel alone. Plus all the bags for the ground, etc. I get 1cubic of good manure for $1 so I have bought a few of those, plus compost since my bin is not producing yet....it ads up!
I cannot imagine doing even half this much again next year and then each year??
I also have a lot of outside plants as well. Ferns, a few Hostas, Violas, Irises, a lot of Morning Gloris directly in the soil, Trumpet Vine and I have a lot of seeds sprouting for future ground cover planting.
But the barrel containers mainly hold tomatoes, 2 different squash share one, Thumbelina carrots, cucumbers, about 6 different peppers, watermelon and canteloupe.
Don't get me wrong, I usually remix and I am sure I will be mixing and composting, etc next year, but to just replace it all..nope.
I would like to know how generations and generations of poor gardeners did it. I cannot see my great grandmother chucking the soil.
Your issues with the soil sound alot like mine. It takes time to fix doesn't it.
I just got off a thread about using bales of straw to garden in. What a great thread.
I am going to have to try that. I want to black plastic a huge section of my garden and see how many weeds I can kill off this season.
So I think that I'll put the bales on top of that and I won't have to go through gardening withdrawl.
I know that in the old days they let a field sit empty every 7 years and rotated crops. I do try to rotate too.
Have fun with the barrel gardening. I have a few barrels too, and after filling the first one with soil, my sister gave me advice. Fill the barrel 1/2 way with stuff that won't decompose easily. I used those packaging peanuts, and a few other items and covered the rest with soil. The flowers grew well, but I haven't tried veggies in them yet. Alot less expensive and more lightweight in case they need to be moved
Well,
you and I sound like we are on the same road. lol
We have to tarp and chip a lot around here because of the severly invasive grass. Well, my neighbor; who has been here since 1962, says everyone that has lived her battled with it and one was a horticulturist! So who am I to think I can win??? LOL
Nope, we tarped and redchippd and set in barrels. It looks neat and I can still do what I want.
It is a quarter acre and the back has beds along a lot of the fencing, along the shed, back of house, etc...but I can only do so much at one time.
And we did do that! A few of the barrels that have things that don't need so much soil, we do have packing peanuts half way up! lol
But with two squash in one and tomatoes root systems, I decided to fill those completely.
Now I realize the question was directed at potting mixes. So I would agree on smaller plants I would probably just put the old in the compost and do new, but I just cannot fathom replacing it all every year.
No I can't either.
I have ended up "rocking" large areas of property that I don't intend to plant heavily. I put down landscape fabric and cut a hole and planted perennials in spots. But weeds still try and come up.
No rest for the weary.
One clarification from me on my original post about resuing soil - I am talking about reusing soil as i pot up or change containers. NOT soil from previous years. And, as i mentioned, I do was pots well with an antibacterial, soak in a bleach solution, and grow everything from seed (nothing from the ground or from nurseries). The reason is about saving money. While I realize there is always a chance that some sort of outbreak could occure, I "think" I'm following a relatively safe practice. At the end of summer the stuff goes into one large raised bed in the back where (this year) I hope to grow onions.
When we grew onions we had too much compost in the soil and many would rot. So just keep away from "too much" and you'll have great onions.
if you were not a 'particular gardener', how would you amend last years soil?
i live in a small apartment. The first year i lived here, i spread out a tarp on the lawn area and made my own soil mix using composted manure and bags of potting soil and perlite, and added the recommended amounts of powdered organic fertilizers specifically for tomatoes, and then grew some beautiful tomatoes in containers. Then i did a mix for cucumers, and then for flowers.
It was wonderful.. I was like a farmer in these here suburbs , however.
i had to persuade a landscaper to take the soil off my hands at the end of the season ( dumping the incredibly heavy planters).. I rinsed off all my planters and containers and did the whole process for two years. Great yields .very happy.
But now i am getting older.
Last year, i just grew flowers. Bought commercial potting mix for containers and used miracle gro..
i am rather ashamed at myself for going this route..but i do live in a small apartment, and my space alloted is just around my apt..
i felt like a real hayseed.( and must admit i was proud of it)
my question piggy-backs on this thread.
I have read with great interest about the decompostion of peat and soil amendments over the year.,etc.
but i just cannot face the heavy work of emptying the containers and finding a place to take the soil.
i am not going to grow veggies this year..just flowers.
i was going to take a rubbermaid bin and empty half of the containers contents.
( ok.it may take two rubbermaid bins)
then i was going to go to Home depot and get some bags of composted cow manure. then i was going to get some osmocote.( hearkening back to my non organic days ) and add this mix to the soil in each rubbermaid, mix well, and use this soil in my containers.
any suggestions as to what i need to add further.,.
i am really forced to go this route because it is so difficult to dispose of the old soil..my apt complex has no garden, no compost bin, no nuthin'..last year, i wheelbarrowed it about a quarter of a mile and dumped it in a field ( across the street from some houses !)
help would be greatly appreciated.
alice
Alice, I can't give you container gardening advice because I'm a novice and there are many experienced people here who can help you with that, but I do want to say that I too am getting older, have lived in apartments, etc... and there is nothing to be ashamed of about buying plants, potting mix, whatever. I think for most if not all of us, regardless of our level of expertice or our methods, in the end it's about getting satisfaction and joy from things we've helped pop up from the soil and grow. KEEP IT FUN and pleasurable. I know you will get great gardening advice from others on this site.
Thanks for the good words, Michael..!!
Brainard,Minnesota..nice territory up there !
i come from cold area also..Gardens are such a treat in the summer.
Oh how we LOVE the summer!
cheerio
alice
rustyswoman...........have you ever done anything with straw bales before? If not, you will be surprised at the amount of weed that will come up if you incorporate that straw into the soil eventually. Most generally, straw has alot of weed seeds in it, however if you can find "GOOD" wheat straw, the weeds will be minimal. Most times, oat straw has tons of weeds in it. I know of what I speak, having been on the "business end" of straw...........i.e...........baling it. LOL Just my 2 cents worth............
Anna_Z - thanks for the tips on straw bales. I have often considered using them as winter mulch on my herb garden, but haven't yet. I will be cautious with them!
perhaps I should clarify something here.........I am talking about plain, ole straw bales you'd get from a farm. Now, if there are people that "make" straw expressly for these purposes (gardeners), perhaps my observations don't apply. Just thought of that................
I think what we all need to remember is that there are plenty of successful mini gardners who simply do and buy from what they get at the store.
If one can only do so much, that is fine. Your plants don't hate you because of it. lol If it has worked for you, more power to you!
My MIL has always had a HUGE garden every year full of plants, flowers, veggies, fruits, etc and she wings it all and it's all great. She doesn't belong to any boards and honestly cannot remember the technical name of any plant. She just gets out there and does.
I personally think too much information can backfire and make easy things seem like huge undertakings. For every opinion there is another 5.....I just want to enjoy and learn as I go on...wihtout breaking the bank. lol
I agree that for every opinion there are several more. See? - here's another: I don't think we can have too much good information. How we use it is up to each individual. There is a great pool of knowledge in boards and forums. Some people choose to drink deeply from the pool - others gargle - personal choices. Information needs to be improved, polished, and increased constantly, or it's lost.
Al
My eyes bugged out when Anna_Z mentioned weeds in the bales. Please no more weeds! Rats, I will have to ask that question on that forum. I am not sure if they kill off the seeds first or not. I do know that the wheat or oats do grow, so I guess the weeds would too. Hmmmm?
Anna is right. I've brought lots of weeds into my garden with straw. I use it to
mulch the vegatable beds.
Tam
Kent, from another forum wrote and said that he doesn't have a weed problem. But he gardens in the bales, not mulches with them. I know they decompose eventually, but I guess that is why he gardens in the bales because they are off the ground away from any weeds! I think I will try a few and see what happens.
Thanks for the input though, I really appreciate everyones ideas and help
I'm going back to the original theme of this thread.
I have roughly ten container pots/window boxes in front of my house. During April, when it was unseasonably cold, I admended all of my flower beds, and enlarged them. I added compost, hummus, bark fines and osmocote. All of my soil is nice and fluffy. I never once considered doing this for the containers.
Last week, I decided that I should remove the pansies that wintered over from the fall. They were actually looking pretty good, but with the warmer weather, I expected them to begin to look ratty shortly.
I pulled all the pansies out by the roots, stirred in some osmocote, and planted my new flowers. I don't know why it didn't occur to me to consider added any amendments at all. All of the flowers were grown from seed by me, so I don't have to worry about introducing outside organisms. The containers actually look great - much better than I thought they would since I really didn't have a plan for them. I used the flowers that I had on hand. When it looked like it needed more, I just began added other flowers or plants.
It's too late for me to consider changing the soil. I am going to add some hummus as a topdressing. I also have a regular program of fertilizing with fish emulsion. I'm considering getting some superthrive as well, since I think that this will provide the micronutrients.
This is a good topic, and frankly made me think. My geraniums haven't begun to bloom yet, but I will post pictures shortly.
And to clarify my original question, I was talking about reusing soil from various containers that I potted THIS YEAR, either soil left from potting up or potting soil I simply had left over from making changes to original plantings. All of the soil had plants I grew myself (not from WallyWorld, or wherever). At the end of the season I typically dump the container soil into a remote raised bed that's in a rather obscure location in the yard (the soil here is VERY sandy). This year I'm trying to grow onions in tha bed.
Well - I dumped last years containers' soil into a huge tub and pulled out all the roots & plant
debris. Then I mixed in earthworm castings & water-holding crystals. I used this soil in the bottem half
of the large containers & baskets and filled the top with new. Potting soil in general is comprised
of materials that do not break down in time - vermiculite, perlite, and even peat are all quite stable.
Personally, I believe that getting the old soil fluffed up is the most important thing to rejuvenate it.
I've used this method with some modifications in years past and never had any problems.
Tam
I've been container gardening for about 6 years and I reuse my soil, but I have a few rules I follow.
I never use brug soil for tomatoes, eggplant, etc or vice versa.
I generally put my used soil in my wheelbarrow or in a rubbermaid tub. As I'm dumping I'm checking out the quality of the soil coming out. (It may be a plants container that I bought somewhere and never repotted or something that was alive for a number of years and then died, seedlings that didn't make it,...)
As I'm dumping I'm deciding if the batch will be used to plant something in the yard, (the soil from a yew I had for years was used to help ammend the soil in the yard where I planted a tulip tree), used to up pot something, plant seedlings in, etc.
Sometimes the soil is really sticky due to the length of time a large population of eathworms have been living in the soil; that gets mixed into multiple batches of recycled soil.
The other day I was trying to do some long over-due maintainence on my container garden and had several pots dump out some really junky soil(a plant from a nursery apparently) . I had a cedar I needed to move into a huge container so I ammended the 'junk' with some peat moss (double duty of acidifying the soil). I also added some water crystals, something I hadn't used in my containers until right before I got sick.
Another thing I take into account is why did the soil become available? The yew (and far more than I care to think about) died due to neglect. (Recurring cancer'll do that for ya.) Some of the junk soil came from plants going into the ground, but the roots hadn't gotten to the bottom 1/3 of the pot, yada yada yada.
One of the great things about mixing my own soil is I have a real good feel for what I like soil to look/feel like and what ammendment it might need to be useful still.
And if you're worried about pathogens, try putting the soil in black plastic bags, seal them well, set them in the hot sun for a few days and viola! Pasturized soil! (Well, down here in deep South Texas it cooks really well. ;->)
Ok,
I'm glad I found this thread, too, cause I've been wondering, too. I'm repotting a buncha container plants in MG potting mix, probably this weekend. Most of what they're in now is NOT potting mix. I think it's old potting soil my DH used before I became the DW. He also uses a trick of filling the pots halfway with decomp leaves and grass clippings. They continued to break down in the pot. So. My question for you all is what do I do with the stuff that comes out of these pots?
Do I throw it all on my worm bin, which is a layer of shredded paper from the office, followed by layers of leaves and grass clippings, and fed with table scraps and MUCHO coffee grinds. It's getting full with earthworms...
At the beginning of spring, I took the resulting decomp from this same type of pile that I had started last summer and sifted it through a wire mesh screen. What I got was some dark, rich, flaked coffee-grinds looking stuff, that I suppose was the "compost." I put this into a small flowerbed and planted my ferns, hostas and Easter Lilies in it. This medium percolates like a charm. The water flows right through, and fast! The plants that're there love it, so I imagine I'm on the right track with the recipe. Just now quite sure what I'm making, and what to do with it once I make it....
Help, please with advice on the above situation. and, thanks, in advance.
Linda
I suppose this will be the year everything rots in my pots, since I'm actually admitting what I do. Except for new pots, I haven't bought new soil in years. I leave the dead plants in all winter and in early spring, cut off the dry tops and compost them. The roots I dig and cut into small pieces with scissors (unless they happen to be particularly woody, and then I compost them, too). I then turn the cut up pieces back into the soil in the pot, stirring it all up thoroughly. This usually raises the level of soil in the pot too high, and some has to be removed. Then I plant, using Osmocote and in some cases soilmoist granules. The original soil in all these pots was potting mix of one kind or another, but as time passed, the cut up roots decomposed and garden-type soil occasionally came with a new plant. The older pots (I'm talking 20+ years here) have wonderful silky soil in them, and things grow well. They are also much easier to rehydrate if they've been in the shed or garage and have dried out. It sounds as if this is living dangerously, but so far, so good. Every other year or so I take out a few trowels of soil and replace them with compost. I garden organically, using only organic fertilizer and compost, in the rest of the yard, but find that with pots the Osmocote and monthly feedings with something soluble (Jack's presently) produce better results. I have over sixty containers and cannot even imagine trying to change out the soil in all of them.
I bought a new house. Its 20 years old. The lawn is "wavy". I use old potting soil to level out the depressions. Stomp it down and water it and the new grass pops through.
ooooooooooohhhh Aguane,
Very good idea!
Hi there!
This is a really interesting thread. I'm new to DG and I'm finding all sorts of interesting subjects. I was wondering if anyone has the answer to something I've been wondering about. I'm kind of like kneff in that I'm mostly organic, particularly as far as pesticides, etc. I also compost, and I'm really happy with my "grow your own"compost. However, I've been using the miracle-gro with moisture control in my annual (and houseplant) containers. The mix is pretty nice, actually. But I'm concerned about it after I'm done with it.
What I want to know is what are the moisture crystals, and what happens to a moisture control granule (or whatever it is) when you compost it? Plus, is there likely to be a higher concentration of fertilizer residue in these mixes? What does that do to my compost? Will it harm anything?
Thanks for any insight!
This message was edited May 27, 2007 11:06 PM
Any Rocket Scientists on board to answer susybell's question.
WOW! This is some question! A good one!
Welcome Susybell! I just received 5 lbs. of polymer crystals from a co-op on DG. There's a question and answer thread at the co-op that will probably have your answer. Or send Llasa Lover a d-mail. She's the polymer crystal guru.
Oh no! Not another thing to worry about!
Yes, I'm guilty of reusing my container soil...I usually have some big focal plant in the middle and pluck out and replace the old depleted annuals when it gets too hot for them, or they've just run their course. Maybe add a little more potting soil but they all seem to be doing well!
I guess if I was to totally re-containerize something though...I should probably replace the soil! (and not dig some sandy crappy soil from the empty lot next door when I run out!).
Thanks for the info!
That was a very funny comment!
I've put much of the contents of my pots into our compost piles and some do have the moisture crystals. I know some people talk about the possiblilties of cancer from the granules but we all have limits on what we choose to get crazy over. The one thing I have experienced is once in a while I grab some compost and little parts of it are exceptionally "squeezy". It's those granules, covered with compost! It always gives me a jolt because right away I think of slugs but I'm almost used to finding it now.
If you don't wear gloves while using compost do you dip your hands in Clorox at the end of the day? I have to and it's a minor miracle how quickly the hands and nails come clean.
suzybell, one thing I can tell you about water crystals is that they don't last forever. I did some research on them a couple of years ago and a scientist told me they only last about 5 years. They break down in the soil.