If I were only able to give one piece of gardening advice, it would be to feed the soil (and let the soil feed the plants). The essence of any garden’s success begins and ends with the soil. And the best way to build the health of any soil is with compost – the greatest organic matter under the sun. Do you know how to compost? If not or if you have challenges with your existing compost pile, this podcast is for you.
What is Compost
Compost is biodegraded organic material. A lot of organisms are involved in breaking down the raw material to finished compost, starting with single celled bacteria, fungi, and protozoa. But they’re just part of the soil food web doing the work of decomposing that material. Arthropods, such as springtails and beetles also play a role. And perhaps the most famous soil-dwelling decomposer, earthworms. The finished product of compost creates humus, the best part of compost.
Why Composting is Important
Compost is important for many reasons. To start, it makes any soil better. No matter if you’re starting with heavy clay soil that drains poorly, or sandy soil that drains too quickly, compost can help with either.
In poorly draining soil, the structure of compost opens space between soil particles to improve drainage, air, and nutrient flow.
In sandy soil, the stickiness of humus, compost’s secret weapon, helps bind soil particles together and helps moisture stick around longer than without it.
In all soil, compost provides nutrients, helps mitigate soil contaminants and pathogens, binds heavy metals, improves soil draining and infiltration, reduces soil runoff and erosion, and improves the overall structure and texture of the native soil.
Composting also dramatically reduces the amount of solid waste going to landfills – the single largest manmade source of methane gas, a highly potent form or greenhouse gas.
Suffice it to say, compost is the single best soil amendment you can add to any soil to feed your plants and help the planet.
How to Make Compost
People that try to compost often get quickly overwhelmed because they think it’s too complicated. But nothing can be further from the truth.
Making compost may be the easiest part of gardening. There are just four ingredients: carbon (brown waste), nitrogen (green waste), air, and water.
Brown waste from inside our homes includes paper and cardboard products (shredded paper, paper towel rolls, and other paper products.
From outside, the most common carbon inputs for compost include leaves, twigs, and yard debris.
Green waste from inside includes vegetable scraps, fruit, salad scraps, and coffee grounds.
From outside, common inputs include grass clippings, yard debris, and poultry manure.
Keep your compost pile or bin often turned to introduce air and each time you turn it, spray it generously with water to wet the total ingredients to the dampness like a wet sponge.
Continue to add greens and browns and turn and spray with water as you build your compost heap to the ideal size (roughly 4’ x 4’ x 4’) to achieve the critical mass needed for the most the efficient breakdown of raw material to finished compost.
Composting do’s and don’ts
- Don’t add meat, dairy or grease. Those inputs can attract unwanted pests.
- Don’t add weeds going to seed. The seeds can persist through the composting process.
- Don’t add diseased plants. The diseases can persist through the composting process.
- Don’t add animal waste from carnivores.
- Be very careful if using horse manure. It may contain a persistent herbicide that can impact your garden soil for several years. (I call it “killer compost” and it had a direct, adverse impact in my garden. I wrote a lot about it.)
Joe’s Top Tips for Quick Compost
- The hotter you can get your compost, the quicker it breaks down. You can make compost in about two months with near ideal conditions. Those include a good balance of green and brown waste, consistent moisture, and air to the core of the heap. I refer to this as active composting.
- In an active composting system, you can approach 150 degrees. Shoot for at least 130 degrees and sustained for several days. That will help kill weed seeds and pathogens.
- Get a compost thermometer (longer stem length of 20-inches.) Monitor and make adjustments as a powerful tool to become a better composter.
- Add all the organic material you can find from inside and outside the house.
- Keep ingredients as small as possible. The smaller the inputs, the faster they break down.
- Seek additional inputs, such as coffee grounds (good nitrogen source) and vegetable culls from the supermarket produce section. This all helps build the bulk.
- Find someone who raises chickens, rabbits, and other herbivorous livestock for a great nitrogen rich manure source.
- Turn your compost heap at least once each week. More is better.
- Spray water long enough, so moisture will get to the core of the pile. Spray longer than you think, so it’s like a damp sponge throughout.
When is Compost Ready to Use in the Garden
Compost is ready to use when you can no longer identify any of the original ingredients. It will have a rich, earthy smell. When you squeeze finished compost, it should clump but break apart easily when you run your fingers through it.
When, How, and Where to Apply Compost
Anytime is a good time to apply compost, but there are better times. Applying compost a few weeks to a month or two before you plant provides important time for beneficial organisms in compost to inoculate existing garden soil. Then, continue to make new deposits of compost once or more per year. Don’t continue to let plants make nutrient withdrawals without making new deposits of compost.
The first time you apply compost to the new soil, lightly work it into a depth of several inches. From then on, topdressing is fine. Don’t till as this will disrupt or destroy the natural soil environment.
Around the plant, topdress or work it into the soil by just a few inches at the most. Overall, strive for 5% compost by weight or 30% by volume. For example, if roots are in the top 6-inches, work in about 2” so that you have about 30% by volume.
Add compost at least around the growing area. If you have excess, spread it out. If you have a limited supply of compost, start by applying it close to where the active roots will be, where it’s most needed. Then work out from there. If you have the luxury of applying it to the entire bed or planting zone, go for it.
With compost, a little goes a long way. You don’t need to apply it excessively unless you have the luxury to do so. Topdressing compost with even a half inch can make a big difference over time if you consistently repeat this process once or twice each year.
Challenges of Composting
- Not making composting a part of your routine. Get in the habit of composting, starting inside the house by saving your food scraps. Store them in a stainless bowl or similar with a tight-fitting lid. Once it’s full, take it out to the compost bin.
- Not locating the compost bin conveniently. Don’t put your bin or heap too far out where you are not likely to utilize it.
- Concerns about an odor. A properly balanced compost collection won’t create an offensive odor. Only when there’s too much wet nitrogen will you likely notice it. If so, cover up with a carbon source, such as shredded papers, leaves, or straw. That will offset the odor and rebalance the ratio of excess nitrogen. You can also get a closed bin system to seal in odor, keep pests out, or eliminate unsightliness.
- Concerns of attracting rodents and pests. Keep food out the compost that is attractive to critters (meat, dairy, grease). A closed bin system addresses this too.
- Compost bins are ugly – If you don’t like the look of an open system, use a closed bin system that contains all the ingredients within a vessel and out of sight.
- Too hard to turn – A valid complaint but there’s an easy fix. Closed bin systems have handles on them that are very easy to turn the barrel. Even a full, large bin with the help of a geared handle allows the bin to be turned easily.
Composting in the Winter
While composting does happen over winter, it definitely slows down. However, fall is a great time to build up your collection of inputs. In fall, you get the bonus of a bounty of leaves. It’s a great source of compostable material.
Shred leaves with a mulching mower or add whole leaves into a trash bin and insert a string trimmer to shred them up (much like a submersible blender). Use a tomato cage or similar to collect and store shredded leaves. By fall, they should be ready to use as compost or mulch.
If you need more than you can make, you can buy it. Look for STA Certified Compost*, a designation of the U.S. Composting Council. Certified Compost has passed an extensive vetting process to ensure viability and the exclusion of unacceptable inputs are not included in the compost that you are buying.
While consumers have no reasonable way of knowing where the input sources originate, STA Certified Compost purchased in bulk or bag provides the best system currently available to screen the composting process before you buy.
Related Links & Resources
Thanks to our sponsor for this episode: Milorganite, makers of a non-burning slow-release organic nitrogen source.
Killer Compost – my post about what happens with you use composted horse manure containing persistent herbicides
How to make a free compost bin using pallets (Video and how-to instructions)
Confessions of an Obsessed Composter – my composting podcast with Lee Reich (from the man who composts everything)
*At the time of this post, I am the spokesperson for the U.S Composting Council. However, the USCC no knowledge of this podcast or notes before posting, nor did they ask me to write this or compensate me for doing so. I use Certified Compost as explained in this post and podcast in the ways described as an additional layer of protection to know the compost I am buying has been vetted.