How to Compost
One of the loveliest aspects of nature is that everything in it has a use—the nasty, rotting zucchini as well as the lavender sprouting scented blossoms in the backyard. Composting can take some of our leftovers, waste and unwanted extras and turn them into fertile soil to boost the productivity of gardens and landscapes. I’ll show you how to compost from start to finish.
What is compost?
Compost is decomposed organic material that is produced when bacteria in soil break down garbage and biodegradable trash, resulting in a product rich in minerals that is an ideal garden or landscaping amendment.
- For one, it’s free. You get to use kitchen waste, lawn clippings, leaves and other vegetation that would otherwise get thrown away. In fact, you might even save money on landfill fees.
- Soils and potting mixes that include compost produce healthier plants regardless of whether you’re indoor gardening, rose gardening or vegetable gardening. (link to guru sites)
- Compost improves garden soil structure, texture and aeration.
- Adding compost improves soil fertility and stimulates healthy root development in plants. The organic matter provided in compost provides food for microorganisms, which keeps the soil in a healthy, balanced condition.
- Compost loosens clay soils and helps sandy soils retain water.
- No need to add fertilizer—just mix compost into the soil. Compost contains nutrients that plants need for optimum growth, such as nitrogen, phosphorus, and potassium. And it’s an especially good supplier of micronutrients that are needed in small quantities such as boron, cobalt, copper, iodine, iron, manganese, molybdenum, and zinc.
- It feels good. When else can you turn trash into treasure? Plus, scraps stay out of the landfill, reducing your footprint.
How does composting work?
You mix yard and kitchen waste in a pile or bin and provide the right conditions to encourage decomposition.
Let bacteria and fungi (microbes) go to work recycling waste material into fertilizer.
Mix compost into garden soil or use it on the surface as mulch.
Sounds simple, right? Well it is. Microbes are hard at work chomping down your throwaways. You supply the organic materials, water, and oxygen. The bacteria that are already there decompose the plant material into compost. As the bacteria break down the materials they release heat, which is concentrated in the center of the pile.
So, how do I get started?
Everyone has a different level of commitment when it comes to composting. For some a rot pile in the backyard is good enough. Others want to apply the rigors of science and constant vigilance to ensure the best (and quickest) compost around. Most of us are somewhere in between.
Use the steps below as guidelines. The more you follow them, the better your compost will be.
- Select a site for your pile or bin. To keep your neighbors happy, consider a discreet location. You’ll also want to locate a spot with good airflow, access to water and partial shade in the summer (to keep the pile from getting too hot), but good sun in the winter (to keep the pile warm).
- Choose a bin. You can purchase a compost bin, or make your own. Rotating bins make turning your treasure easy and keeps animals out. Or you can make a workable bin on your own. One simple method is to track down shipping pallets. Use one for the bottom. Pound in metal support poles and add pallets by slipping them over the support poles to make your bin’s walls. Make your pile about 3X3X3 feet. This size is big enough to create its own heat, but small enough to turn. If you are using a commercial composter you won’t need to worry about the size.
- Add materials. Not everything can go into the compost bin; read on to find out what can and cannot be composted.
|Vegetable scraps||Meat or animal products (bones, fish, eggs, butter, yogurt etc.)|
|Egg shells||Coal ash|
|Yard waste (lawn clippings, leaves)||Weeds or weed seeds|
|Manure (from vegetarian animals)||Pet droppings|
|Coffee grounds and filters||Synthetic chemicals|
Check out Can I Compost This? to find out more about what can and cannot be composted.
4. Monitor temperature, aeration, moisture and the carbon to nitrogen ratio for optimum levels.
If you follow the steps to composting, you should have great results.
The easiest way to test your compost’s temperature is to stick your hand in the center of the pile. If it is hot or warm—good job. If it is the same temperature as the ambient air, the microbes have slowed down—and so has the composting process.
You can also use a compost thermometer to take your pile’s temperature. A compost pile that is working well will produce temperatures of 140-160°F. At these temperatures almost all weed seeds and plant diseases are killed. A “very hot” compost pile will generate temperatures of up to 170°F for up to a week or more.
Everyone needs to breathe, even tiny microorganisms, so make sure enough oxygen is getting into your pile by turning your compost often.
If you are using easily compacted materials (such as ashes or sawdust) mix in coarser materials first. People who build large piles often add tree branches or even ventilation tubes vertically into different parts of the pile to be shaken occasionally, maximizing air circulation.
The microbes that do your dirty work in the compost pile require just the right amount of water. Too much means organic waste won’t decompose, too little and you’ll kill the bacteria. Compost should feel moist, but not soaking wet—like a wrung out sponge.
Composting works best with 40-60% moisture content. More on measuring water content here.
Carbon to Nitrogen Ratio
For the best compost, maintain a C:N ratio of 25 to 30 parts carbon to 1 part nitrogen, or 25-30:1. If the C:N ratio is too high (excess carbon) decomposition slows down. If the C:N ratio is too low (excess nitrogen) you will end up with a stinky pile.
In general things that are brown (dried leaves, newspaper, straw) are higher in carbon than things that are green (vegetable scraps, garden waste, grass clippings).
5. Mix rich, earthy compost into garden soil, or pile on top of the soil as mulch.
Need the best wheelbarrow to move your compost? Check out my wheelbarrow buying guide.
Here are a few more tips to turn carrot tops (and anything else) into compost more quickly:
- Help start a new compost pile with aged manure, cottonseed meal, alfalfa meal, blood meal, or compost starter. They are rich in nitrogen and help jump-start the microbes responsible for breaking down organic matter into compost.
- Chop or shred materials before putting them in the compost pile or bin. The smaller it is, the faster it will break down.
- Plants that have been treated with pesticides and/or herbicides (weeds and lawn clippings) should be avoided.
- Algae and seaweed make excellent additions to your compost pile. Be sure to rinse off any salts before using.
- Add a lot to your pile at once, rather than in small doses to encourage the pile to heat up.
- Turn, turn, turn. Turning compost will introduce oxygen and speed up the composting process.
- Keep you pile or bin in the sun. Microbes are more active when warm.
- Activators can speed up a slow compost pile.
- Got compost? When finished it should look, feel and smell like rich, dark soil. You should not be able to recognize any of the items you put in there.
- Finished compost is usually less than half the volume of the materials you started with, but it’s much denser.
- Apply finished compost to your garden about 2-4 weeks before you plant, giving the compost time to integrate and stabilize within the soil.
Does your compost stink? Is it dry and brittle? Is nothing happening? Are maggots freaking you out? Check out these troubleshooting guides to find out what’s wrong.