Topic: Last years' growbags

[bluecar]

Hello all.

I was going to add the old compost from my growbags to my compost bins up at the allotment, but I wondered whether there was any other use for it?

Regards

Bluecar

[Tee Gee]

I wondered whether there was any other use for it?

A lot will depend upon whether the previous crop was diseased or not, but if not what I use 2nd hand compost for is to fill the bottom third of containers to save on the price of new. Afterall with many plants, the bottoms roots are water roots and the feeding roots are higher up the root ball in the fertilised new compost, so anything that holds moisture is fine by me.

[johhnyco15]

i do much the same thing i put them in my bean trenches along with green waste and grass clippings the top it of with new compost it works really well hope this helps

[Vinlander]

There's pretty much nothing I can't kill by microwaving 4L of old compost for 20 minutes (I do try to get all the centipedes out first - centipedes are very much on "our side" in the battle against pests... I also try to remove worms - but boiled slugs are good fertiliser!)

You end up with a compost that is much more sterile than anything you can buy, and it's also slightly depleted in nutrients - if it spent a year as a growbag it's now perfect seed and seedling compost. If you want to use it to make sure your bigger plants are free from any new pests like fungus gnat etc. then you just need to add a bit of fertiliser.

Cheers.

[bluecar]

Thanks.

These suggestions are, I think, are better option than just adding to the compost bin.

Bluecar

[Hector]

Vinlander.....I have a delicious image of you using kitchen microwave. Reminds me of a friend who cleaned car parts in dishwasher....just the once.

[Vinlander]

Vinlander.....I have a delicious image of you using kitchen microwave. Reminds me of a friend who cleaned car parts in dishwasher....just the once.

Hi Jackie - microwaving soil-less compost hardly makes any smell - but if you've mixed in >10% soil/John Innes as I sometimes do - then the smell is about 50x worse (but it makes the compost much easier to re-wet - I think it's the silt and clay that works as a wetting agent).

The answer is a dedicated microwave - I rely on "gomi" - microwaves dumped in the street. They usually work OK (stand them in a fireproof area, plug in and stand well back). Sometimes it's only the plate that's damaged and you can often use the plate from the one you just blew up.

Some of them might have been dumped only because someone made them smelly...

Cheers.

[ancellsfarmer]

The classic Gro bag was developed to grow tomatoes, basically "bog standard" compost, allegedly based on treated sludge from the civic works. Others have been repackaged waste from amenity tippings. Mainly they will have depleted  the nutrients and could be re-energised with a blended compound such as growmore or Vitax q4. It would be risky to grow another crop of the same type due to blights and moulds, but might serve for ,say, salads,to start off beans or for dahlias or herbs when revived. Any incorporation as part of the additional build up to topsoil would be ok but for me its too valuable to compost.

[Vinlander]

It would be risky to grow another crop of the same type due to blights and moulds.

I agree with everything you say - but that's why I microwave depleted compost for use with precious seeds and cuttings. The alternative is paying top dollar for stuff you already have by the sackload.

Sterility of bought compost is an illusion anyway... A few weeks in store will allow all the normal microorganisms (and maybe worse) to get fully established - and though that might be a healthy ecosystem it can still overwhelm some of your precious seeds & cuttings. I chit my most precious seeds in readymeal boxes that have been microwaved with damp paper inside, and transfer the seedlings to recently microwaved compost (used and depleted).

I did experiment with washing the seeds in weak oxygen bleach (permanganate) but got mixed results - I might try again with weak peroxide sometime - it should be more predictable.