A friend of mine

has a dirt/rock yard. She sells sand, garden soil etc. Another friend of mine went to work there and she and I both got some of the garden soil. I haven't gotten around to using it yet but my friend did. It is burning her house plants.

My friend whom owns the dirt yard told her it isn't to be used for house plants just garden plants. The owner planted her tomatoes in it and it burned them up. She puts mushroom compost, sand, topsoil, chicken manure etc. I told her it makes no sense to me. I always use it on all my plants I told her the additives haven't been composted enough. The worker friend it is still very hot when they stir it with the bulldozer.

Why would it be good for garden and not all plants?

I think the best solution is to ask the person who said that, why. But my guess is that she is assuming that outdoors the stuff she sells will be mixed with garden soil which will dilute it's strength. I agree with you that anything that is too hot, has not been composted well.

>> burning her house plants

Usually when I hear "not for house plants", I think of something that doesn't have enough drainage to be used in containers. Like too much clay and silt but not enough sand, grit, fine gravel. And not enough well-composted organics to support soil life that would help support soil structure / openness.

Is it possible that bad drainage caused something that looked like burning up? Like maybe (just guessing) no water flowed THROUGH the pots so nutrients and salts built up in the pot and that caused the burn?

One big difference between outdoor soil and containers is the the entire depth of outdoor soil acts like a big wick that keeps water and slats flowing down and out of the root zone, preventing toxic buildups.

Or maybe acid pH from too-rich soil fermentation made some nutrient toxic at a concentration that might otherwise have been bearable.

It's a rare dirt yard that sells garden soil that's TOO RICH in organics! But if that's what they're doing, you could cut it with 50% to 75% pine bark in a "grit" size and have some great, cheap soil!

>> The owner planted her tomatoes in it and it burned them up. She puts mushroom compost, sand, topsoil, chicken manure etc. I told her it makes no sense to me.

Does the owner of the dirt yard add mushroom compost and chicken manure before selling the garden soil, or were they added after the garden soil was brought home? I forget whether chicken manure is hotter or cooler than cow manure, but I seem to recall that it is very concentrated.

I talked to the owner yesterday and she says it holds too much water is why it is not good. She told me to buy miracle grow for my potted plants. But I disagree because this last year most potting soil is 75%+ bark mulch. She said bark mulch helps it drain but it needs soil also.

Rick she adds the mushroom and chicken before she sells it. I do believe the mixture is not composted enough is why it did burn her tomatoes but for my friend whom potted plants is because it doesn't drain and too hot.

She said she didn't know how to make it more draining but wouldn't adding mulch, perlite and whatever else help it to drain. Of course this is after it is well composted. The bags I got I am adding to my newly started compost pile.

Mushroom compost can be really high in salts, and it would make the plant look "burned," either in a container or in the ground.

ssgardner if it is high in salts what can I do to make sure it isn't? Or what can it be used for?

Sandy, for the best medium for container plants, consult the sticky at the top of this forum by Tapla. He is a soil scientist and has helped many of us with our soil problems. The sticky from Tapla is gone but look at the post near yours by Gymgirl or just go to threads started by Tapla

This message was edited Dec 21, 2013 3:29 PM

I'm afraid I don't know!

I have heard that if you let it age for a long time in the open, and let it get rained on, that the salts will eventually wash out. I don't know if that's true. I just tried to look up this information but most research sites just recommend avoiding mushroom compost for plants that are sensitive to high salt content (like azaleas and tomatoes).

Here is some info of "Mushroom Compost" no wonder it is burning plants.
http://www.natureswayresources.com/resource/infosheets/mushroomcompost.html

>> it doesn't drain and too hot.

Ouch! That, plus mushroom compost with high slat content is a triple-whammy.

I may be simplistic, but I tend to think that "good drainage cures all ills". Maybe there is a little truth to that if "good drainage" includes "good aeration".

Anyway, if you can get her rich, salty mess to drain well, then water it or let it be rained on so that water runs OUT the bottom, you can flush away excess slat and nutrients.

If there is no other way to make it drain, spreading a THIN layer assures that water can find its way out. A few rains will wash away any excess salts (and wash away many of the nutrients if they are already composted.

Adding a lot of coarse material is practical if the rich stuff is only SOMEWHAT poorly draining. I'm a big fan of shredded or ground bark (I learned that from Al / Tapla). Particles bigger than BBs, or bigger than 1/10 inch, are good. Particles bigger than 3/8" or 1/2" might be an inefficient use of the bark: you would get more mileage out of 2-4 nuggets at 1/4" than you do out of one big 1" chunk.

If you have lots of sandy soil, that will help it to drain if you use it in an outdoor bed. (Keep garden soil out of containers unless it drains really well and you already know you can make it work).

If it is pure clay and silt or sludgy organic matter, you might need lots more grit than you have sludge to make it drain well! In other words, add just a little of the too-rich stuff to something that is now too-fast-draining.

If the parts of the mix that are too fine are also organic (not fine minerals like clay), they will be consumed as they compost. Thus some of the poor-drainage parts will "go away" as you let air into the mix and make water drain out.

It they are non-nutrient salts, I guess you want to let it run off somewhere it won't hurt other plants. Or be wary about mixing "salty" organic mix to soil that lacks good drainage.

But if it is just excessive N and other nutrients (which can also be accurately called "salts"),

In that case you would want to let it run off into some lean soil that needs the (diluted) nutrients that were burning roots when they are too concentrated. Or mix it with something that is now infertile and needs rich NPK and organic matter.

You have to guess whether it is "bad salts" or just too much of a good thing.

"The dose makes the poison": excess N kills plants, but the right amount nourishes them.

I have started a new compost pile and I am going to add the bags of this I got to it. It will be a good while (maybe a year) before this pile is good enough to use so all should be good by then. When they remove some of the garden soil from the pile my friend said it smokes like it is hot smoke not dust. That tells me some of its ingredients are not fully composted. So I don't want to use it for anything right now.

Salts is that salt like in table salts if not what is "But if it is just excessive N and other nutrients (which can also be accurately called "salts")," ?

Ive heard others here on DG say to "stay away from mushroom waste" that it is bad stuff. I dont know anything about it first hand, however.

>> When they remove some of the garden soil from the pile my friend said it smokes like it is hot

Yowsuh! That is rich in organics and nitrogen, at least! Composting sounds perfect.

I bet while you are doing that, you are also greatly enriching whatever soil sits under your heap! When you use the compost, maybe you could also excavate some of the soil under it, screen it, and add that to a bed?


"Salts" can be any soluble mineral. When they build up to excessive levels they can "burn" plants by making it impossible for the plant to take up water. I think that too much nitrogen is even more toxic than just its saltiness would explain. (I forget why, if I ever knew why).

Table salt is Sodium Chloride, and I can't think of anything less useful to plants. It's bad for them because it makes it harder for them to take water out of the soil (osmotic pressure, or something close to that).

Magnesium Sulfate is also a salt (Magnesium Salt), but plants need a little magnesium and a little Sulfate, so a little of that would be good.

Potassium Sulfate and Potassium Nitrate and Potassium Phosphate are all salts, and they are also nutrients, because plants need lots of Potassium (K) and Nitrate (N) and Phosphate (P) and a little Sulfate.

Nutrients are worth the bother of diluting them (as you are doing with your composting). Plants need them and will "consume them" or at least remove them from the soil and build them into plant tissue.

Salts that plants DON'T use have no redeeming value, and you want to flush them away to keep your soil healthy.