Weeds and how to Compost them.

How to compost

Which bin to choose

Compost Safely

Your compost ingredients

Emptying your Bin

To turn or not to turn?

How long to compost?

Worms and Wormeries

Topical Composting

Kitchen waste

Prickly prunings

Weeds and Weeds

Too much grass

Leaves for Leafmould

Seasonal Tips


Advice sheets

Unwelcome Guests

Weeds love warmer weather and we spend most of the summer trying to control them. If they escape the garden hoe, they can often be composted. Annual weeds make a good, green, sappy addition to the heap and the small amounts of soil clinging to their roots contain millions of beneficial bacteria that will help the composting process in your bin. ‘Nasty’ perennials, like couch and docks, should be treated differently.
annual weeds
Annual weeds

It is best to add annual weeds like groundsel, chickweed and bitter cress to your compost bin before they flower, so there is no risk of having their seed in the compost. However, if your bin is working at a high temperature - because you’ve placed it in a sunny place, have added a good mix of green and brown ingredients and kept them moist, even these weed seeds will be killed off. If some seeds do germinate, it’s easy to hoe them or add them to next year’s compost heap. Don’t be wasteful by throwing these weeds out. Your garden will benefit from the nutrients that they add to your compost and the improved soil structure will encourage much healthier growth in your plants.

perennial weedsPerennial weeds
The roots of ground elder, couch grass, nettles, creeping buttercup, dandelions and docks must be kept in darkness for 2 years. Since compost can often be used after one season, these roots will still be alive, so will keep on growing. (Leaf growth can safely be added to the compost bin, provided no roots are attached.) There are many ways of dealing with these roots as they do contain valuable nutrients.

Drown them!
Place the roots in a bucket, cover with water and carefully weigh the  roots down with a stone or slab to keep them under the water. Place a lid on the bucket and leave for several weeks. Drain off the liquid  and pour onto the compost heap. You can also dilute the liquid and use it as a plant feed, but it is difficult to know exactly how strong it is. A mix of 5 parts fresh water : 1 part weed water will act as a general feed for container grown plants. The drowned roots can then safely be added to the compost bin.
See Make your own liquid feeds for full instructions.
Stew them!
Put the roots in a black plastic bag and mix 50:50 with fresh grass clippings. Tie a knot in the bag and leave it in a sunny place for a few weeks. By this time everything will be a soggy mess, the roots will be dead and the contents of the bag can be safely composted.

Cover a badly infested plot with black plastic, remembering to sink the plastic to a spade’s depth round the edge. After 2 seasons, the weeds will be killed off and the roots won’t have spread into the surrounding ground. The soil will be completely clean and will have benefited from weed nutrients.
If you want the plot to ‘look good’ while all this is going on, cover the plastic with an attractive mulch and grow herbs, lettuce, strawberries or flowers in containers.

Some more of Dave's thoughts on Composting weeds and diseased plants

celandineThere are a very few perennial weeds that should not be added to a compost heap: Lesser Celandine (Ranunculus ficaria); Horsetail (Equisetum arvense) and especially Japanese Knotweed (Fallopia japonica)

If all else fails start eating some of your weeds - they can be an asset.
Some weedy recipes amongst the herbs others in the greens.

                                                                   Lesser Celandine (Ranunculus ficaria)