To compost weeds in a bokashi system:
This should be long enough to kill even the toughest weeds. You can then use the resulting compost on your garden.
What does that mean?
4. Bagging (Good for Large Quantities)
If your compost pile gets plenty of heat and is steaming to the touch, then weeds can compost in as little as 6 to 8 months. To get your compost piles hot enough requires a perfect mix of browns and greens, regular working and (ideally) a sunny location. The heat from your compost should damage and destroy roots and seeds so that your weeds will not propagate from the compost.
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Don’t throw them away! Your garden can benefit from all of those extra nutrients. Leaves aren’t the only thing you should be composting from your yard!
Bokashi composting is a popular method for composting food waste. Bokashi composting can also be used effectively to compost weeds. The bokashi composting process uses microbes to ferment organic material. This fermentation process creates an acidic environment which will kill seeds and roots of your weeds.
The classic method of composting—the method purists would call the “right” way—is known as hot composting. This simply means that you turn the pile regularly and allowing it to really heat up to 145 degrees Fahrenheit or more. A properly maintained hot compost pile will kill weed seeds, as well as many other pathogens, so you can compost weeds without having to worry about them popping up in your garden beds.
How do you know if your compost is getting hot enough to kill all weeds? A variety of compost thermometers are available that can gauge the temperature of your pile. Experienced gardeners may simply thrust a hand into the pile. If it feels uncomfortably warm to the touch, it likely is warm enough to kill all seeds and roots in the pile.
Compost is a great way to recycle organic material in your garden. All those spent flower blossoms, fall leaves, dead plants, grass clippings—even non-meat kitchen scraps—can be transformed into a great soil amendment and nutritious mulch, simply by throwing them into a heap and allowing the refuse to decompose naturally.
A gardener who experiences such an explosion of volunteer weeds may well swear off composting altogether, or at least stop adding weed material to the compost pile. To be clear, there is no reason to stop composting weeds. With a slight adjustment to the composting process, you can ensure that weeds and their seeds will be killed completely and won’t be resurrected where you least want them.
This can actually be rather charming when the volunteers are tiny impatiens seedlings, tomato plants, or even pumpkins that volunteer because last Halloween/s jack o’ lanterns were added to the compost heap. It’s far less charming when the volunteer plants are hundreds of dandelions or tiny sprigs of bindweed or crabgrass that get into the garden via the compost you spread.
Done correctly, composting creates a sterile organic material that does nothing but good things for your garden and the plants in it. However, nearly every gardener who practices composting has occasionally experienced “volunteer” plants sprouting up in the garden where the compost has been spread.
For hot composting to fully kill all weed seeds and roots, follow these tips: