composting weed seeds

[charlesModerator]

Hi Charles

 

I remember you had a rotary composter when I visited. I am looking to buy one for making/mixing a good compost for potting herbs and possibly seed sowing. We have a lot of problems with weed seeds still germinating in our compost. It gets turned and left for a year and looks fabulous (and works brilliantly on the tomatoes) but we are obviously not getting the temperature up high enough to kill the seeds which is why we considered the drum.

 

How do you get on with yours and where did you get it?

 

regards, Jan Billington

[charlesModerator]

 Hi Jan

Thanks for your message which I am posting on the forum.

 

I do not recommend the composter, it costs over £300 and although good at turning, I think that too little air enters to feed bacteria, so decomposition is not fast at all. Also heat is lost through all sides being exposed to air.

I continue to make compost in my old wooden heaps, turn them once and wait patiently for another 3-6 months before spreading the compost, and 6-9 months for heaps assembled in winter. Leaving even longer can give finer compost, good for potting.

Weed seeds is another issue and I recommend you not to have them! I burn the few I find here and am mostly composting weeds before seeding stage. Except for commercial composting where heaps are turned enough for all materials to be hot at some stage, I think most of us struggle to attain enough heat to kill weed seeds. 

I am happy for somebody to correct this statement, with a process they have used and works and is viable!

 

[Pete BuddParticipant]

I have tried to produce potting compost but never found it viable. It really needs sterilizing by heat treatment. So unfortunately I spend quite a lot on potting compost. Like Charles I use wooden bins for my compost with very little in the way of ventilation and rely on a long cycle and turning once. Its mainly green manure with veg waste and includes all weeds including; wick grass roots, mares tail, docks, nettles, dandelions, seed heads etc. A bin is filled up in year 1, turned at the beginning of year 2 and spread at the beginning of year 3. Any resulting weed germination is dealt with by regular shimming.

[charlesModerator]

 Hello Pete, thanks for this interesting post, also for your post on green manure which I hope someone else will engage with. I do not use them for reasons of saving space and time, but you have a point about the possible problems of importing manure.

Re potting compost, I have found mint to work well, have a look at the post ‘compost’ by Sarah Bell, under sowing and growing, where I uploaded some pictures of a compost trial I did last year.

Having said that, I use West Riding compost for potting because it grows so well!

[Pete BuddParticipant]

Hi Charles; yes I agree about the West Riding Compost but its so expensive if you buy small quantities. I suppose I should get together with some others and buy in bulk but I don`t know enough people who would be interested.

Pete

[Don WoolleyMember]

A general comment. I have several of the round plastic bins.One is a Rotol bin,the type that Jim Hay used and suggested in his book Vegetables Naturally.It has a rather steep conical shape and easily , and consistently, out performs all the others
I too have seen Charle’s garden and don’t think any weed dare show it’s head there let alone seed ! !Don Woolley

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