One common tip we see online, in gardening books, and when talking to other gardeners is to use “high quality compost”. We even talk often about building your soil with great compost and how the soil is the foundation for your plants. In this tip, we’ll try to break down what most we mean by the term “high quality compost” and how you can work towards improving and creating the best, high-quality compost for your garden.
First off, what is compost? Generally speaking, the term compost is a catch-all term. As a noun, it means decayed organic matter commonly used as a fertilizer or soil conditioner. As a verb, it means the act of breaking down organic matter.
Compost is created naturally when leaves, dead plants, manure and other animal and plant byproducts get broken down into smaller and simpler elements. This occurs anywhere microorganisms live and is often consciously facilitated and sped up through the use of compost piles, wind rows and specialty bins.
Home made compost is generally made in an outdoor bin using household materials like food scraps, shredded newspaper and dried leaves. Generally speaking, the quality of the input materials will affect the quality of the finished product. Because everything going in is most likely high quality (from a compost perspective), the results should be excellent in the garden. Common faults include moisture content (either too little or too much) and imbalance in ingredients (dry, brown carbon-based materials vs. wet, green nitrogen-based materials).
Leaf mold is created exclusively with leaves. Depending on the type of tree the leaves came from, it can be more acidic (like from oak leaves with higher tannins) or more alkaline (like from maple leaves). You can make your own leaf mold with a lot of leaves and patience. If you can chop up the leaves into smaller pieces (we suggest making several passes with your lawnmower), it will compost and break down faster. You can also use shredded leaves as a mulch material right on the surface of the soil in the garden.
Mushroom compost is the byproduct of mushroom cultivation. It can include ingredients like sterilized horse manure, sphagnum peat moss, brewer’s grains, wheat straw, corn cobs, cocoa bean shells, lime, and gypsum. Each mushroom grower usually has their own mix based on the types of mushrooms they grow. Often the ingredients are chosen for their organic matter, being readily available and inexpensive. Because of the variability, ask the grower what ingredients they use, and/or try a sample before purchasing a large quantity. You may find they may be low in nutrients, high in salt, and sometimes high in price.
Composted manure is exactly what it sounds like. Manure from various animals are composted until it is in a more stable form. Sheep, and cow manure are the most common types found in garden centers. Horse manure can be obtained directly from horse farmers. We’ve seen chicken manure typically in smaller or granular packages and forms. Bat guano we’ve only seen from specialty online or mail order catalogs or as an ingredient in a fertilizer blend. As the manures breaks down, it heats up, which should kill many weed seeds, reduce its odor, and provide slow release nutrients to the garden. In general, we recommend horse and chicken manure over cow manure for urban gardens.
Worm castings is like composted manure, except it is made exclusively from worms. Various types of worms can be used with the most common being red wiggler worms (Eisenia foetida) and European Nightcrawlers (Eisenia hortensis).
All of these types of compost can be excellent sources of good, high quality compost. Depending on how the the animals are fed, how they are composted and broken down, and how they are stored will determine how good your finished compost will be. For a fine texture, compost can be screened (put through a sieve with various sized holes) to separate larger chunks of materials that haven’t finished composting yet from the rest of the materials.
Hopefully that clarifies some confusion when it comes to the word compost. Depending on the context, it can mean different things and you’ll be better able to identify good quality compost to use in your garden in the future.