Spent tomato growbag compost

[John O]

Dear All,
This is my first message on this site.
I have an organic allotment in Sussex. The soil is greensand so requires a fair amount of feeding which I do each autumn/winter. This season I will have available 15 used tomato growbags in the autumn. This is from a greenhouse project that I have had this summer. I am considering using the spent compost from the growbags to dig into my allotment, in the knowledge that it will be devoid of nutrients, but simply to bulk up the allotment soil. I have a couple of questions:
1) Is this a good idea? Are there any downsides to doing this?
2) I will, of course, need to feed the soil as well. I usually use material from my compost heaps and/or well rotted horse manure. Would these coexist with the spent growbag compost OK? Or should I consider something else?
Thanks for any thoughts on this.
John

 

[Becky]

Welcome to the forum @John O There are lots of tomato growers here so hopefully someone will have had experience with this

 

[Chuck]

Dear All,
This is my first message on this site.
I have an organic allotment in Sussex. The soil is greensand so requires a fair amount of feeding which I do each autumn/winter. This season I will have available 15 used tomato growbags in the autumn. This is from a greenhouse project that I have had this summer. I am considering using the spent compost from the growbags to dig into my allotment, in the knowledge that it will be devoid of nutrients, but simply to bulk up the allotment soil. I have a couple of questions:
1) Is this a good idea? Are there any downsides to doing this?
2) I will, of course, need to feed the soil as well. I usually use material from my compost heaps and/or well rotted horse manure. Would these coexist with the spent growbag compost OK? Or should I consider something else?
Thanks for any thoughts on this.
John

The "spent" compost will be a great additive so long as the plants grown in it previously did not have some kind of disease. Compost turns into soil and just because something was grown in it doesn't mean that it has somehow turned into some sort of sterile waste. It will still have all sorts of nutrients in it. The only time soil is spent is when all organic matter is gone and soil bacteria and fungi have been destroyed. And this happens after prolonged use of chemical fertilizers.
I do have a question though. You said your soil is greensand. What's that? Over here Greensand is mined, bagged up and sold as a soil amendment as it is a product full of all kinds of minerals

 

[alp]

Just incorporate some chicken manure, horse or cow manure and BFF. As @Chuck points out, as long as it has not had any disease in the spent compost, you could always re-use it. Perhaps, a good idea to do some crop rotation ie. not growing tomatoes in it.

 

[John O]

The "spent" compost will be a great additive so long as the plants grown in it previously did not have some kind of disease. Compost turns into soil and just because something was grown in it doesn't mean that it has somehow turned into some sort of sterile waste. It will still have all sorts of nutrients in it. The only time soil is spent is when all organic matter is gone and soil bacteria and fungi have been destroyed. And this happens after prolonged use of chemical fertilizers.
I do have a question though. You said your soil is greensand. What's that? Over here Greensand is mined, bagged up and sold as a soil amendment as it is a product full of all kinds of minerals

Good point about the tomatoes having some kind of disease. I guess blight would be the most likely. I shall look out for that.
The greensand here is an alluvial soil which I believe originated from rivers and streams which once ran here. It is about 1 metre deep and sits on a sub soil of clay. There is a narrow ridge of it which runs through part of the village that I live in. Luckily this includes my allotment. I say "luckily" because it is easy to work, all through the year and is very good for growing root crops. It does, however, drain quite sharply so needs a good feed each year.
Thanks for your help.

 

[John O]

Just incorporate some chicken manure, horse or cow manure and BFF. As @Chuck points out, as long as it has not had any disease in the spent compost, you could always re-use it. Perhaps, a good idea to do some crop rotation ie. not growing tomatoes in it.

Thanks. Sorry, but what is BFF?

 

[DirtMechanic]

Thanks. Sorry, but what is BFF?

@alp what is BFF? I know FBB as fish, blood, bone? Were you typing up a whirlwind?

@John O sterility is a real fight. The longevity of fungal spores is impressive and measured in years. You have to starve them out, and that itself is not easy and is usually accompanied by advice such as fallowing the land for some years or planting other crops. Exposing a half inch of soil to the sun on a hot black plastic surface until it is radiated by uv and dry as death might be about all that is practicable in DIY volumes of soil. The potted plant growers cook their soil.

 

[headfullofbees]

I have "gro-beds" in one of my 6x8 greenhouses (39 aubergines from 5 plants in 10 days) and each year I use the compost on my onion beds.
I have a good crop whilst others have struggled.

 

[TomatoTango]

It’s fine unless a horrifying disease got a specific grow bag but always amend the soil before planting, during plant life cycle, and also right after pulling. I add recycled potato grow bags back into my compost and it blends right up.

 

[headfullofbees]

Even if it does have some disease, if you have only grown tomatoes in it, the disease is very likely to be confined to them and other solanaceae.
That's why I use mine as I do.

 

[thisgardener1]

It’s fine unless a horrifying disease got a specific grow bag but always amend the soil before planting, during plant life cycle, and also right after pulling. I add recycled potato grow bags back into my compost and it blends right up.

I think I quite agree with Tomato Tango on amending the soil. I haven't planted tomatoes before, but that's just what came to my mind when I first saw this.

 

[DirtMechanic]

I would get a small drum or metal can and boil the used soil for 10 minutes then dip it out and use it how you will and pour the liquid where you will. You may choose to boil the bag as well, if they hold up.