How to amend your soil

[Gilcano]

Hi all, I'm looking to amend the soil in my containers. I mixed the soil (potting soil) of the 55 gallon barrel with a bag of cow manure about 2 years ago but I'll like to add some fertilizer. I looked and found some methods of doing your own potting mix and save some money in the process because buying bags of ready potting mix could be quite expensive.

I'm thinking to get a 40 lb bag of Azomite, some Agricultural Garden Lime and some bags of Worm Casting to revitalize the soil in my containers.

After some investigation and before get bombarded I learn that the fertilizers need to be added in small quantities like. Here are some of the DIY soil I found:

Recipe #1
2 - 5 gallon of Sphagnum Peat Moss
1 - 5 gallon of Horse Manure (cured)
1 - 5 gallon og Organic Compost or Worm Casting
1 - 5 gallon of Perlite
1 cup of Agricultural Garden Lime
1 cup of Epson Salt

Recipe #2
1 - 5 gallon of Brown Peat Moss
1 - 5 gallon of Black Peat Moss
1 - 5 gallon of Perlite
1 - 5 gallon of Organic Compost
Base Fertilizer (Make 1 gallon)
1 part Bloodmeal
1 part Greensand
1 part Phosphate Rock

[tomc]

I find soil in a container (specifically the organic parts of it) continue to decay and become smaller. Leading to soil compaction and poor air penetration. Once I'm done with soil it goes into the compost and (ultimately) the garden.

I make between 75 and 200 gallons of soil per year. I wouldn't reuse soil.

[rainbowgardener]

I do re-use soil, but only by dumping it into a wheelbarrow or something and adding equal quantity of new soil and mixing together. Once a year I do this to all my containers.

I don't think just adding fertilizer is sufficient, for the reasons tom mentions.

[toxcrusadr]

It does break down, reducing the particle size leading to compaction. Reviving it is probably best done by adding very coarse shredded organic matter - like shredded bark. The peat moss and perlite will help some.

If you're adding compost, my gut feeling is those fertilizers and lime are excessive. They will make the mix heavier and denser too which you don't want. I have had great luck with container tomatoes using basically a 1:1:1 mix of last year's potting soil, sifted compost, and fresh commercial potting mix. I don't have to use a lot of fertilizer. There are other recipes out there for container mix too. Lots of folks seem to like Al's Gritty Mix (you can search for the name).

[Susan W]

Need to get some basics before any suggestions. About how many containers? size? what are you growing?
I have 100, or is that going on 150 containers, small being 10" large 16"+. Most are perennial herbs. The smaller ones with annuals (flowers, basil etc) get dumped in the compost, and that pile really enriched dirt. For larger ones with annuals, I usually wait until spring. Then pull out old and some dirt. Then add. The lower 2/3 is rich from previous, has worms and more.

The basic mix I use, changes with each batch, is about 1/2 bagged top soil, 1/4 bagged manure (I like black kow) and 1/4 bagged cotton burr or soil conditioner. Then some scoops from my compost aka enriched dirt pile. If you are growing veggies and flowers, can add some slow release fertilizer such as osmocote.

[ElizabethB]

I have lots of potted patio plants. I revive the soil every 2 or 3 years. My ratio depends on the condition of the existing soil. I may use the existing soil and mix it 1/3 existing soil, 1/3 potting soil and 1/3 compost. Any left overs go into the compost bin. If the existing soil is nice I will mix it 1/2 existing soil and 1/2 compost.

Much depends on your plants and your environment.

Good luck

[imafan26]

It is not that easy to reuse soil. We do that at the garden, but there is a soil steam sterilizer. We still have to sift the soil and remove most of the dead roots. The soil cooker steams the soil for about 4 hours. It is then put in barrels and we can use it for transplanting, but we would still prefer to use new potting mix for seeds.

If the soil is not sterilized, there could be some soil borne diseases that might cause problems and a lot of weeds will grow in the pots competing with the plant. Any leftover fertilizer in the mix can cause other problems because unless you want to test that mix to see what you need to add to it, you can't always use the same fertilizer as a virgin mix.

I usually take my old potting soil to the garden where I volunteer to be sterilized or I put it out in my yard and use fresh potting mix in the pots. I found that especially heavy feeders like tomatoes did not do well for me if I tried reusing the soil.
If I failed to remove all of the roots from the previous planting, they would start to decay and the pot did not drain as well.

[ElizabethB]

Imafan - you got me. Sterilizing your soil? Aren't you also killing desirable organisms and destroying nutrients? "Sterile" soil is just that - sterile and not suitable for planting. Think of the great dust storms that stripped the living soil from so much of the central part of the country. Soil is a living thing. Sterile soil is no longer soil. It is dirt. Dead dirt.

Sorry. Just really surprised at the notion of sterile soil.

[Gilcano]

I do re-use soil, but only by dumping it into a wheelbarrow or something and adding equal quantity of new soil and mixing together. Once a year I do this to all my containers.
I don't think just adding fertilizer is sufficient, for the reasons tom mentions.

What do you call "new soil": fresh commercial potting mix?

Need to get some basics before any suggestions. About how many containers? size? what are you growing? I have 100

WOW that's a lot of containers.................... I'm planning to have 20-30 only, mainly 5 & 6 gallon buckets and some 15 to 18 gallons storage totes. This is what I'm planing to grow: TOMATOES 2 plants of big tomatoes such as beefstake, 1 plant of Roma tomato and 1-2 plants of Cherry tomato. PEPPERS 1-2 plants of ea, Red, Green, Yellow Bell Pepper, 2-3 plants of Jamaican Hot Chocolate Pepper, 2-3 plants Trinidad Scorpion, 2-3 plants of Fatalii Pepper, 1-2 plants of Jalapeno Pepper, and 2-3 plants of Cayenne Pepper. 1-2 Plants of Cucumbers, 1-2 Plants of Zuchinni and some Lettuces, Parsley and other Herbs which can go in the garden tower.

Imafan - you got me. Sterilizing your soil? Aren't you also killing desirable organisms and destroying nutrients? "Sterile" soil is just that - sterile and not suitable for planting. Sorry. Just really surprised at the notion of sterile soil.

I thought the same thing......................

[Susan W]

Are these existing containers that have had plants, and you are freshening for this season? Filling new containers? So many variables

[toxcrusadr]

Steam sterilizing is only really necessary for seed sprouting mix because sprouts are susceptible to fungal blights and whatnot.

You can't really sterilize it totally - I worked in a lab where we did some soil experiments with 'sterile' controls and even after autoclaving (essentially pressure cooking), *something* microbial would always survive and grow eventually. Scientific geekery just for your enjoyment.

Drainage gets worse with reused potting mix because the natural breakdown of coarse fibrous materials makes a finer texture which doesn't drain as well.

[rainbowgardener]

what I mean by new soil is either fresh commercial potting mix or my own homemade potting mix, which is described here https://www.helpfulgardener.com/forum/vi ... 48&t=60534

In no case do I mean or include garden dirt, which I never put in containers, even as an ingredient in a mix. Other people who have sandy soil might be able to do that, but my garden dirt is practically pure clay, way too dense to put in a container.

[Gilcano]

Are these existing containers that have had plants, and you are freshening for this season? Filling new containers? So many variables

OK let me see if I can explain myself, the soil I want to amend is on a 55 gallon barrel (equivalent 11-5 gal containers) plus another 7/8 - 5 gallon containers so close to, let say 20 - 5 gallon containers. I will amend this soil to double the amount of containers (40). I'm trying to calculate how many pounds of Sphagnum Peat Moss and Perlite I need to add to revitalize the 55 gallon barrel. For example if I take one of the 5 gallon that was planted already and mix that soil with an equal amount of Peat Moss and Perlite, meaning:
1 - 5 gallon already used soil
1 - 5 gallon of Sphagnum Peat Moss
1 - 5 gallon of Perlite
1 gallon of Worm Castings
1 cup of Azomite
That will give me enough soil for 2-3 5 gallon containers, right? Well that's what I want to do.

[Susan W]

I have to say I wish I could help, suggest, encourage, share etc, and certainly not tell you what to do. But, we are on totally different wave lengths!
You have time before working your pots, and I do suggest checking around for options. It will work and you will have tomatoes and others good stuff.

[imafan26]

Steam sterilizing reused soil does kill soil microorganisms. It does not always kill fungi especially if it is too wet going into the steamer and then put in covered cans where it cannot really dry out.

I don't worry about losing microorganisms in reused soil, most of what I would be losing would be pathogens and weeds which both of which have caused me more issues when I don't sterilize the soil. I don't do organic in pots, I use fertilizer and I can reintroduce the microbes with AACT and vermicompost.

[rainbowgardener]

RE:
1 - 5 gallon already used soil
1 - 5 gallon of Sphagnum Peat Moss
1 - 5 gallon of Perlite
1 gallon of Worm Castings
1 cup of Azomite

should work. My basic potting soil recipe is something organic like compost, something fluffy like peat moss or coconut coir, something loose and free draining like perlite or rice hulls in roughly equal amounts. You basically have that, except that your 5 gall of already used soil has had a lot of the nutrients and texture depleted out of it. You are making up for the nutrients with the worm castings and azomite. What is left is texture. As has been mentioned, the used potting soil gets kind of broken down in to smaller particles which can compact. The azomite and worm castings are both also very fine textured. You could make up for that by increasing the proportion of perlite or adding in something else with a coarser texture, maybe some coarse sand or a bit of shredded bark.

[Gilcano]

RE:
1 - 5 gallon already used soil
1 - 5 gallon of Sphagnum Peat Moss
1 - 5 gallon of Perlite
1 gallon of Worm Castings
1 cup of Azomite

should work. My basic potting soil recipe is something organic like compost, something fluffy like peat moss or coconut coir, something loose and free draining like perlite or rice hulls in roughly equal amounts. You basically have that, except that your 5 gall of already used soil has had a lot of the nutrients and texture depleted out of it. You are making up for the nutrients with the worm castings and azomite. What is left is texture. As has been mentioned, the used potting soil gets kind of broken down in to smaller particles which can compact. The azomite and worm castings are both also very fine textured. You could make up for that by increasing the proportion of perlite or adding in something else with a coarser texture, maybe some coarse sand or a bit of shredded bark.

Thank you