Why Gardeners Swear by Biochar — And How You Can Make Your Own

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Why Gardeners Swear by Biochar — And How You Can Make Your Own originally appeared on Dengarden.
It's possible you've heard of biochar or know someone who uses it, but if you're reading this, then you might be wondering what it is. Although it's a relatively well known gardening material that's been used for the past 2,500 years in the agriculture space, it's not as popular as it should be, especially since it has benefits for both plants and the environment.
Ahead, we spoke with a gardening expert about all things biochar from what it is to how to make your own so you can use it next time you're tending the garden.
What is biochar?
For starters, biochar is a black carbon made from materials such as wood chips, manure, plant residues and paper mill waste.
According to the the US Biochar Initiative (USBI), it is made by a process known as pyrolysis that involves heating biomass (wood, manure, crop residues, solid waste, etc.) with limited to no oxygen in a specially designed furnace to capture all emissions, gases, and oils for reuse as energy.
This process is not only beneficial for gardening, but also the environment and managing climate change as it helps to keep harmful gases and heat out of the air and in the ground instead.
What does it do for your garden and yard?
Biochar has been shown to have several benefits for gardens and yards. First off, you might notice an increase in plant growth and yield when adding biochar to growing soils, according to Edwin Dysinger, a gardening expert and co-founder of Seedtime.us. In the same vein, you might notice you need less fertilizer when using biochar too.
Plants with shallow roots and those with a long growing season such as tomatoes, strawberries, asparagus and red peppers tend to benefit the most from the addition of biochar.
Aside from aiding in growth, Dysinger says that biochar can help improve water retention in soil. "Multiple studies have shown that biochar increases water retention, especially in sandy soils," Dysinger told Parade. "It may also reduce nutrient losses due to leaching and this is something to keep in mind for container and raised bed growing where soils often dry out quickly in summer heat."
Additionally, the use of biochar has been shown to provide a favorable habitat for soil microorganisms such as mycorrhizal fungi. "In the same vein, it has also been shown to increase microbial diversity when added to compost and to speed up decomposition," Dysinger says.
How to make biochar
While you can buy biochar at the store you can also make your own if that's more up your alley. Dysinger has some step by step directions on how to do this yourself at home:
Gather the materials
First, you will need space to dig a three foot diameter pit away from nearby combustible materials, a shovel or post hole digger, a bucket and a water source, and biomass of your choice - leaves, sticks, wood, etc.
"The basic concept behind biochar (and charcoal) is that wood burns twice," Dysinger says. "Once to become char and then a second time to become ash. The second burn (to become ash) requires oxygen. In this process of biochar production, your goal is to achieve the first burn, and to then add biomass on top of it, preventing it from completing the second burn."
Prepare the area and burn it
Next, dig a V or cone shaped pit and that should be about 2.5 feet wide and 3-3.5 ft deep. The apex (point) of the cone should be the deepest part of the pit as this shape helps to control airflow.
Then, you'll loosen the soil at the bottom and make a teepee of wood in the bottom and light it. Once it is burning well, knock it down and add more biomass on top. The goal is to almost, but not quite, smother the fire. Once the added material is burning well, repeat the process.
"There should be little to no smoke as you do this. If it does become smokey, usually it will be because you almost smothered it," Dysinger explains. "Let the fire build up again until it isn't smokey, then add more material. Once your material has all been added, or your pit is full, douse the fire with water or cover it with soil. If you cover it with soil, let it wait several days to go out and cool down."
Add materials and charge it with nutrients
Following that step, small materials can be more efficiently added to your soil and used to store nutrients and house microbes. If you burn larger pieces of wood, you can put them in a bag and then crush them with a hammer or other large object to get crushed biochar.
Lastly, now that you have biochar it will work better and faster, if you charge it first with nutrients. "In fact, if you don't charge it first, it may initially take nutrients from your plants as it absorbs them and charges in the soil," Dysinger says.
To do this, put your biochar in a bucket, barrel or tub and soak it with a nutrient rich solution in a one to one biochar to solution ratio. The solution could be a tea made from compost, worm castings, liquid kelp, fish emulsion or even urine. Let it sit in this solution for a couple of weeks to fully charge. Cover with a lid to prevent flies, but make sure it is vented (not on tight). You can use this biochar as a mulch around your plants, or work it into the top four to six inches of soil.Why Gardeners Swear by Biochar — And How You Can Make Your Own first appeared on Dengarden on Jul 22, 2025
This story was originally reported by Dengarden on Jul 22, 2025, where it first appeared.
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