Among experienced gardeners, organic natural compost is sometimes referred to as "black gold" because of the many benefits it offers as a garden soil amendment:
- Improving soil structure
- Aiding microbial activity in the soil
- Attracting earthworms and beneficial insects
- Moderating temperatures and moisture levels of soil
- Providing slow-release, organic nutrients
Best of all, there is no soil amendment that is cheaper or easier to create than ordinary compost. Compost is simply the end product that results when organic matter decomposes naturally under microbial action. Virtually all organic matter, if heaped together and allowed enough time, will break down into compost, but you can speed the process along with some simple techniques for controlling the conditions of decomposition.
What Is "Organic" Matter?
By the strict definition, "organic" refers to any material that is based on elemental carbon molecules. Because all living things are based on carbon, "organic" can be defined as any material that was once living—both plant and animal life. But when it comes to creating garden compost, it is generally just the plant-based materials that are appropriate as fuels for compost. While substances such as meat scraps and pet excrement can, and will, eventually break down, it's not good practice to include these animal-based materials in your compost heap, as they may contain disease-causing pathogens and parasites.
Before Getting Started
The recipe for creating an effective compost that can be used as a soil amendment can be summed up as follows: "Organic plant-based material + moisture + air + time = garden compost." With the right mixture of materials and careful attention, a heap can become useable compost in just a couple of months, though it more often takes six months or so.
Allowable materials for making compost include garden waste, fruit and vegetable scraps from the kitchen, leaves, grass clippings, paper, twigs, etc. These materials thrown together will eventually decompose into a fine-textured, dark-brown granular material that is much prized by gardeners. The decomposition process naturally generates heat, and by the time the compost cooking process is complete, weed seeds, fungus spores, and other undesirable elements should no longer be viable. The finished compost looks like rich soil. It’s dark and crumbly with a pleasant earthy smell.
Compost is not particularly high in essential nitrogen, phosphorus, and potassium (N-P-K), and compost alone does not eliminate the need for secondary fertilizers to feed most plants. But for plants with minimal nutritional needs, compost may provide be all that's needed. And it can reduce your dependence on chemical synthetic fertilizers. Spreading a thin layer of well-decayed compost over your lawn as a top-dressing, for example, can eliminate the need for at least one summer feeding of your lawn.
While there are many methods of composting and many composting bin styles, there is no best method. The important thing to remember is that you can never add too much compost to your soil. There are two basic approaches to making your own compost: active and passive.
- Passive composting is the "compost happens" school. All you need to do is pile up your organic matter and wait. It can take many months or even a few years to fully decompose, but eventually, it will. However, the passive composting process may never generate the heat needed to kill off weed seeds and spores.
- Active composting requires varying degrees of effort. Truly active composting involves being somewhat precise with the layers you add to your compost pile, turning it regularly to provide the necessary oxygen for the decomposition process, and monitoring moisture levels to keep things barely damp but never soggy.
When to Create Compost
Maintaining a compost heap can be started at any time, but once started, the practice becomes ongoing as you constantly add food scraps, plant clippings, and other organic materials to the compost. Even in cold-winter climates, a compost heap can continue to generate heat and break down materials well into freezing weather. Some northern gardeners have even been known to maintain indoor compost heaps through the entire winter. Or you can store organic materials outdoors in sealed containers to add to the compost heap when warm weather returns.
Composting makes sense for anyone looking for an organic, environmentally friendly means of conditioning garden soil and feeding plants.
Equipment / Tools
- Garden hoe or rake
- Compost bin (optional)
- Brown and green matter for compost
- Hardware cloth as sifting screen
- Granular nitrogen fertilizer (optional)
Choose a Location for the Compost Bin or Pile
You'll need an out-of-the-way (but accessible) space at least 3 x 3 feet in size, large enough to hold either an informal heap of compostable materials or a purchased or constructed bin. Properly maintained, your compost should not be overly smelly, but most people prefer to tuck the compost area in a less visible area, but where it is is still handy for adding materials.
Add Brown and Green Layers
For the first layer, lay a 3-to 6-inch layer of "brown," carbon-rich material, such as dried hay, straw, or dry leaves. Even shredded newspaper or cardboard can go in this brown layer. On top of this, add a layer of up to 18 inches of "green" nitrogen-rich material, such as plant debris, kitchen scraps, and grass clippings. Think of this "green" layer as moist plant-based material that was recently living; the "brown" layer is plant material that is old and dry.
Any type of organic material that has not been treated with herbicides or pesticides can go into your compost. But it is usually best to exclude plant material that was diseased. Plants with fungal or bacterial infections, for example, should be disposed of separately and not added to the compost. These pathogens can sometimes survive the heat of the composting process to reinfect your garden once the compost is used. And it's usually a good idea to exclude weeds, especially perennial weeds, as their seeds may also persist.
Some common materials include:
- Green material: Coffee grounds, garden trimmings, prunings, grass clippings, hair, kitchen scraps, rotted manure, seaweed, and tea leaves.
- Brown material: Cardboard, corn cobs and stalks, leaves, newspaper, shredded paper, pine needles, sawdust, straw or hay, and wood ash.
Add eggshells, too, which are neither green nor brown, but still add some calcium to the mix.
Alternate brown and green layers until you reach an overall size of about 3 feet wide and 3 feet tall. This is usually sufficient to get the composting process underway. If you don't have enough green material for the initial pile construction, then sprinkling a thin layer of nitrogen fertilizer between brown layers can have the same effect.
Water the Compost
Water the pile until it is damp throughout, but not soaked. It is a common mistake to frequently water a compost heap, but this is not only unnecessary but counterproductive, as an overly wet pile will be smelly and will not decay any faster.
Cover the Pile
When the pile reaches its full size, cover it with a tarp (commericial compost bins usually have a lid) to keep the nutrients from washing away and to prevent it from getting too wet.
Turn the Pile
Using a garden hoe or rake, turn the pile every couple of weeks to make sure it stays uniformly mixed. The goal of this action is to distribute air into the pile, as oxygen is necessary for the decomposition to occur.
A good rule of thumb: if your compost pile is not generating any warmth, is it probably is too dry and needs some added moisture. If the pile is smelly, it is probably too wet and needs to be turned to add air. A proper compost pile should not be unpleasantly smelly and some modest warmth should be evident as the natural result of decomposition.
Replenish the Pile
The organic materials will gradually shrink in volume as the decomposition progresses, so you can continue to add more brown and green layers as the pile shrinks. However, this replenishment process should not continue indefinitely, as there will come a point where you want the pile to fully break down in anticipation of using the compost in your garden. Most people find that a month or two of steady replenishment, followed by a couple of months allowing the compost to complete its decomposition, is a good rhythm. Remember to frequently turn the pile during its completion phase.
Many gardeners find that having two, or even three compost piles is the best strategy. This allows one pile to be completing its process while the others are in earlier stages of development.
"Harvest" the Compost
When it is crumbly and resembles soil more than debris, it's time to sift out the large pieces that have not yet decomposed and start using your compost. A homemade screen made of hardware cloth with 1/4- or 1/2-inch grids can be an excellent tool for sifting compost. The finer material that sifts through the screen can be used immediately as a soil amendment or mulch, while the coarser material that separates out can be added back to the compost heap.
How to Use Compost
Compost can be added to your garden at any time, either turned into the soil or used as a mulch or top dressing for established plants. You can add it just before planting time or amend your beds in the fall and let the natural freezing and thawing process work it into the bed.
How much compost your soil needs will depend on the quality of the soil. The more you add, the better your soil will become. It's really hard to go wrong when adding compost, but it's not a one-time fix. You'll need to amend your beds annually, which is why gardeners always say there is never enough compost.
Once you recognize the value of compost in the garden, it's entirely possible that you'll be unable to make as much compost as you want. But never fear: you can buy compost by the bag or by the truckload. Either way, it's good to know the source.
- Bagged compost: The problem with bagged compost is that you don't really know what you're getting until you bring it home and open the bag. Many times, compost by the bag is composted manure, which is usually fine. To be on the safe side, look for the word "organic" on the label. That would offer some guarantee that the contents are not contaminated with undesirable ingredients
- Bulk compost: This is definitely the cheapest way to purchase compost. Just as important, you can see what you're getting before you get it home. Don't be afraid to ask what they are using to make their compost and if it is organic.