How to Add Non-Seeding Weeds into Compost

How to Add Non-Seeding Weeds Into Compost

Composting weeds is a great way to replenish your garden with nutrients that the weeds might have taken away. Of course, you’ll want to prevent them from sprouting in your compost and in order to do that you’ll have to follow some steps to make sure you’re not spreading weed seeds in your garden.

Whether you’re just starting out in the garden or are a seasoned green thumb, having your own compost is a great way to reduce waste and keep your plants happy. And while most people are more than happy to toss their food scraps into the compost bin, some are hesitant to throw weeds in there, too.

Considering how persistent and hardy weeds are, it’s natural to be nervous about adding them to your compost pile. But there is no better compost filler than the weeds that are already growing in your lawn and garden.

Benefits of Composting Weeds

If you’re still uneasy about composting weeds, consider:

Returning nutrients to the ground. One of the reasons why weeds are so hard to eradicate is their strong root systems. The roots absorb a huge amount of nutrients from the soil. By composting weeds, you are feeding the nutrients they have absorbed back to your plants.
Easy disposal. For proper compost, you need both green and brown materials. Weeds provide green material from their stems and leaves and brown material from their roots. Instead of taking time to bag up the weeds, you can place the whole plant into the compost bin, making for easy cleanup.
Reduce weed populations over time. While you’ll never be able to get rid of weeds entirely, removing the entire plant will reduce their population. If you pull up a plant before it seeds, you are also preventing future generations from spawning.

How to Make Compost With Weeds

When done correctly, composting should create a sterile organic material that basically acts as a natural fertilizer for your plants. Composting comes with its own set of challenges, but when you add weed to mix, you really need to be vigilant. Many gardeners have ended up with even more weeds than before, prompting them to stop throwing weeds into their compost heap.

There are two main methods of composting: hot and cool. Hot composting requires constant temperature monitoring and mixing. For beginners or amateur gardeners, it might be a bit too much work. However, the benefit of hot composting is that the compost will reach high enough temperatures to kill off any seeds and roots.

The cool composting method is more informal and relaxed. Instead of mixing, you add fresh materials to the top of the heap while the lower levels break down into compost. You can periodically remove the compost from the bottom of the pile as the fresh materials pile up on top. This takes longer, but it’s much easier. With that said, you’ll have to be more careful about how and when you add your weeds as the heap likely won’t reach the necessary temperatures to kill them.

Troubleshooting Tips for Composting Weeds

To make sure you don’t encourage more weed growth in your garden, it’s important to pay attention to when and how you add your weeds, especially if you plan on using the cool compost method. Remember, weeds are hardy so you really have to make sure that you’re following the appropriate steps to ensure they won’t germinate when you spread your compost. If you follow the tips below, you should be able to have a nutrient-rich and sterile compost:

Keep the right temperature. In an ideal hot-compost heap, the temperature can exceed 145 degrees F. At this temperature, most seeds and roots should die — yes, even weeds. The best way to know if your compost has reached the appropriate temperature is to use a compost thermometer. You should measure different parts of the pile to make sure the temperature is even throughout. If there are cold patches, then any seeds or roots in that area could end up surviving and spreading. You’ll have to turn the compost every so often to keep the materials aerated and to ensure they reach the necessary heat to kill seeds, roots, and seedlings. If you manage to get the compost to the right temperature, it should kill anything that is growing.
Harvest before seeds form. While this isn’t as important for a hot compost, it’s a step you should take if you plan on using the cool-compost method. Since the compost likely won’t reach high enough temperatures to kill off weeds, adding in weeds that have already seeded is basically a recipe for disaster. In general, early spring tends to be the best time to remove weeds from your garden as most of the plants will not go to seed until later. Dandelions, for example, take as little as eight weeks to go from seedling stage to bloom, and then just another week to go from bloom to seed, so you’ll have to work fast!
Pre-bake weeds. Most plants will be safe to add to your compost pile so long as you heat it to high enough temperatures to kill both roots and seeds. Even if you do decide to go the hot-compost route, you can always pre-bake your weeds for additional peace of mind. There are plenty of ways to do this. One way is to toss your weeds into a black bag and set them out in the hot sun for a few days. If you have a microwave, you can put the weeds in there and "nuke" them for a few seconds until they steam before you add them to your heap.
Let compost age. If you manage your compost pile well, it should be ready in as little as two months. However, if you’re dealing with weeds, you should probably let it go a bit longer, especially for the hot-compost method, to ensure the seeds and roots are truly dead. Compost can keep for at least a year, so there’s no rush to use it immediately. Take your time and look over your compost to make sure you don’t notice any seedlings popping up. If everything looks fine after a few months, go ahead and use it in your garden.

Weeds are the bane of many gardeners’ existence, but they can also serve as an excellent source of nutrients when added into a compost bin. Just make sure that you take the necessary precautions before you use your compost. Otherwise, you might have a dandelion or crabgrass outbreak on your hands!