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how to compost weeds with seeds

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.

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.

Composting Issues

For hot composting to fully kill all weed seeds and roots, follow these tips:

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.

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.

I have always made compost. Currently, I have a wormery plus a Hotbin chugging away in my greenhouse. These make weed free potting compost and the glorious ‘worm wee’ that fertilises the greenhouse crops. I also have a stack of three tractor tyres that composts large quantities of organic matter plus four black bins that were sold very cheaply by my council a few years ago. These bins get hot and turn garden waste into compost quickly. I often mix them mid cycle to speed up the process. My leaf mould bins have disintegrated. I need to build another one.

Here is the detail.

Maddy is trying to become 100% self-sufficient in compost by composting everything, even tricky weeds that seed easily. Here are the 5 steps she uses to achieve fertile, no dig beds mulched with her own compost.

Here is the uncovered bed with weed seedlings. Lots of them!

So now I am hoeing the seedlings. I only hoe the top mulch. The bed below is undisturbed. I will leave this bed empty until I know the seedlings have been eliminated.

My aim is to compost everything I can and become self-sufficient in fertility in my no dig veggie garden area. I grow a lot of comfrey too and make comfrey tea. And I use green manures but sparingly. I find digging them in a chore and they often don’t want to go away.

1.) First, make sure that the weeds you wish to compost haven’t gone to seed. Unless your compost heats up to 140°F, those seeds will survive and spread in your garden. My style of composting can be fairly passive; it just doesn’t get turned as often as I’d like. Therefore, I don’t add any weeds to my compost pile that have gone to seed because I know that it won’t always heat up to 140°F.

When I look at weeds, do you know what I see? I see plants that have removed minerals from the soil in which they were growing. And because of that, I want to compost them so that those nutrients can be returned to my garden soil. But composting weeds presents some challenges. Here’s how to compost them the safe way.

All sorts of items are compostable from grass clippings and leaves, to egg shells and natural fibers. Find a list of items you can compost here. And yes, even weeds are compostable if you take a few precautions.

Why Stepping on Your Garden is a Bad Idea

The roots of garden plants love loose soil which allows their roots to go deep for water and nutrients. Stepping on soil compacts it, reducing the space available in the soil for air and water.

5.) Lastly, you can place your weeds in a black plastic bag and allow this to heat up in direct sunlight for about a week. I prefer not to use plastic in my garden, so I’ve not used this strategy too often.

While we get very few weeds in our garden beds, this bank in front of our house is another story.

A 2 – 3″ layer of mulch does a great job of keeping weeds at bay by blocking the sunlight that the weeds need to sprout. We use both hay and wood chips as mulch in our garden.