Some of my best plants this year seem to be the weeds!
I have some that have seed blossoms set but no flowers open. I want to cut them off before they bloom just in case I don’t get to fully weeding them out till it is cooler.
Quesiton is, can I throw these clippings into the compost bin or will I find they somehow land up setting seed and making the compost a mass of weed seed?
Another question, what weeds do you NEVER add to the compost pile (crab grass?, anything that runs wild in the garden?)?
I never add perennial weeds that can sprout new shoots from little pieces. This may be OK to do if you are very diligent about making and turning your compost, but I am pretty lazy, and I don’t think my compost ever heats up enought to kill anything. Plus most of these weeds (mugwort, oriental bittersweet, that weedy aster — Symphyotrichum lanceolatum) are pretty persistant.
There are some plants that can make seeds after being pulled up if they have already been in flower long enough. I will have a look through my weed books to see if any of them contain information about this. You would need to look up each of your weeds to see which flowers will be OK.
This list and how-to from Gardens Organic (England) is one of my favorites on why to compost and no compost:
Scroll down on that great page (part of the most comprehensive composting site I know of) for the info on weeds/weed seeds, which includes this advice about bagging (to solarize/cook to death) the unwanted weeds, BEFORE adding them to the heap:
“Some perennial weeds will be killed in a hot heap; avoid really persistent horrors such as celandine, docks, bulbous buttercup, ground elder and bindweed. Don’t burn or dump these weeds – they are rich in plant foods. Mix with grass mowings in a plastic sack. Tie it up and leave for a few months until the weeds are no longer recognisable, then add to the compost heap. Or send them to your local council green waste recycling facility where the composting methods are hot enough to kill them off.”
The bagging idea is great — a sort of waste not, want not tactic for recycling them versus tossing them into the trash — and you can use a few bags over and again. The weeds I bag instead of adding right to the heap include any with strong runners (like goutweed, or former garden plants I now find too ambitious like plume poppy or ajuga) and any that have started to flower before I pulled them.
P.S. — More on weeds (particularly on ID’ing them so you know what you are up against) in this blog post:
I said “thank you” in the forum, but wanted to come back here and thank you also for the very helpful info.
A quick question on the black bag method, do you poke holes in the bottom and sides so water drains from the bag over time?
You are welcome, TerryK, and no, I think no holes in the bags. Let them really smother and cook! (Devilish, aren’t I?)
Since I have no grass clippings because of drought, I’m going to try your technique with my bumper crop of crab grass! Think I can try this with garlic mustard (before seed set) or microstegium? I have even more of those.
Thanks for answering this question. I have to try adding the crab grass too.