What makes a good leaf composter?
Not all compost bins make for a good leaf composter. Here are some of the things I look for when picking a leaf composter.
- Large capacity and size. To make leaf mold you need a lot of capacity because the pile needs to be pretty big. Look for something at least 3x3x3 feet in size. Most commercial compost bins are too small for leaf mold.
- Durable construction. Leaf mold takes a long time to make, so you want a bin that will weather several winters with no problems.
- Easily expandable. I don’t know about you, but I always end up with more leaves than I bargained for. For me, this means that expandability is a big plus when it comes to picking a leaf composter. Also, since leaf compost can take over a year to make, it’s good to have the option to create a two or three bin system so you can have different piles at different stages.
- Good aeration. Leaf mold is generally a low maintenance compost and not something you want to be putting a lot of time or energy into making. This is why it’s so important to find a bin with good aeration – it’s one less thing you need to worry about.
- One thing that’s less important is rodent protection. Since you aren’t putting any food waste in the bin, pests generally aren’t interested.
Leaf mold vs compost
Leaf mold is not the same thing as compost made with leaves.
They are made differently, and they also offer different benefits for your soil.
What is leaf mold?
Leaf mold is a soil amendment made using nothing but leaves. Large amounts of leaves are collected, then left to sit in a pile and rot down by themselves. No nitrogen is added.
Compost is also a soil amendment but uses a mix of ingredients rather than just one thing. Compost needs ingredients high in carbon and nitrogen. Leaves can form the carbon element, while things like grass clippings, food waste, or manure provide the nitrogen.
Making leaf mold is a much slower process than making traditional compost. With traditional compost, heat-generating bacteria that feed off nitrogen do most of the work. However, with leaf mold, the lack of nitrogen means that normal composting bacteria can’t flourish. Instead, fungal networks are the main decomposition drivers.
These fungal networks take longer to build up and work at cooler temperatures. Compost can be ready in a few months, while leaf mold will take at least a year to make.
Leaf mold vs compost
As I mentioned above, leaf mold takes longer to make and requires more room than compost. You have to be okay with dedicating part of your yard to decomposing piles of leaves.
However, it’s lower maintenance than normal compost because you don’t need to worry about balancing the C:N ratio, and turning isn’t required.
Leaf mold as a soil amendment is really good at increasing your soil structure and water retention ability. Good topsoil will hold around 60% of its weight in water, while leaf mold can hold up to 500% of its weight in water!
However, leaf mold cannot be used as a substitute for fertilizer because leaves aren’t high in nitrogen, phosphorus, or potassium. For these nutrients you need compost. That said, leaf mold will add some trace minerals to your soil such as calcium and magnesium.
Of course, if you’re able to, the best thing to do is to make both. You can use some of your leaves to make leaf mold and the rest can be used as brown material in your normal compost bin.
How to make leaf mold
Leaf mold is an easy to make, low maintenance type of compost. Below I’ve put together a quick, 5 step guide on how to make leaf mold.
Step 1: Collect the leaves
You’re going to need a decent amount of leaves if you want to make a leaf mold pile. The pile should be at least 3x3x3 feet in size to ensure some level of protection against wind and rain.
A leaf vacuum is an excellent tool that makes collecting leaves quick and easy. They’re also fun to use! I use the WORX 3-in-1 leaf tool. It’s a blower, vacuum, and mulcher all in one. So you can collect the leaves and shred them at the same time.
If you don’t have enough leaves to make an open pile, you can always use the garbage bag method. With the garbage bag method, you only need enough leaves to fill one bag.
Some leaves are better than others for making leaf mold. Good varieties include ash, beech, birch, or maple. More waxy leaves like holly are less ideal because they take an extremely long time to break down without heat.
The fresher the leaves are the better. Freshly fallen leaves will have a higher nitrogen content than leaves that have been sitting around for a while. This initial boost of nitrogen will help get the decomposition process underway faster.
Step 2: Shred the leaves
If you’re stuck on how to shred such a large amount of leaves check out my article on how to shred leaves for compost where I’ve come up with some very inventive ideas. My favourite one is running them over with a lawnmower.
Step 3: Build the pile and water
Once you have all your leaves you can create your pile. Either build an open pile using one of the bins I suggested above, or a black trash bag if you don’t have many leaves.
If you’re using a trash bag, make sure to put some holes in the bottom of the bag to aid aeration and moisture control.
If you’re using an open pile, a good tip is to cover it with some tarp or old carpet. This adds an extra layer of insulation and also stops too much rain from overwatering the pile.
For both methods, the leaves will benefit from some moisture. Add enough to make the leaves damp, but you shouldn’t be able to squeeze water out of them.
Leaf mold is made without any added nitrogen. However, if you want to make leaf compost, now’s the time to add a source of nitrogen to the pile.
Step 4: Wait and turn the pile (turning optional)
Making leaf mold is not a quick process. It will take at least a year before you have a useable soil amendment, maybe even longer.
To speed up the process you can turn the pile every few weeks, though this isn’t a necessary step. Turning can help aerate your pile, dry it out if it becomes too wet, and prevent matting.
Make sure to check the moisture levels in your pile every so often, especially after a particularly wet or dry period. Add more water if the pile feels a little dry.
Step 5: Collect the compost
Once the leaves have turned into a dark, crumbly soil-like substance, your leaf mold is ready to use.
How to use leaf mold
Leaves tend to have an acidic pH, with some being more acidic than others. For example, pine needles are known for being quite acidic. However, as the leaves decompose they lose this acidity and become more neutral. You don’t have to worry about leaf mold altering the pH of your soil.
Leaf mold can be used in much the same way as compost. Here are a few ideas:
- Use it as mulch. If you use it as mulch, make sure it doesn’t touch the stalks of your plants directly. Because it holds so much moisture, the leaf mold can cause disease if it comes into contact with the base of your plants.
- Add it to potted plants. Mixing a bit of leaf mold into your potting mix will help improve the mix’s water-holding capacity.
- Mix the leaf mold straight into your soil in places you think could do with lightening up. Leaf mold can help improve the structure of heavy soils.