You've been composting your yard waste and kitchen scraps all summer, and watering and turning your pile faithfully for weeks. As summer vegetable gardens wind down and many people prepare their garden plots for fall planting, you may get the urge to harvest your hard-earned compost. Your garden is ready for compost, but is your compost ready for the garden? There are a few guidelines for assessing the quality and maturity of your compost, and if you have keen eyes and a trusty nose, you're ready to decide!

1. Has your pile shrunk in size? If the pile is less than half of its original size, the compost may be ready.
2. Has everything decomposed? Not everything you've put into the pile will have decomposed at the same rate, but if the majority of your ingredients are unrecognizable as the newspaper shreds and banana peels they once were, chances are the compost is ready to use.
3. Is it dark and crumbly? Does it have an earthy smell? If the compost smells a little too much like week-old vegetable scraps, not all of the necessary decomposition has occurred.
4. Is the pile still getting hot? If you have a little patience and your garden beds can wait, you can turn and water the pile one more time, and if in a couple of days or so little or no heat is generated, rest assured that the decomposition process is complete.
   

For most people the four guidelines listed above should be enough, but if you don't trust your eyes and nose, or you just have a penchant for science, you can perform a simple experiment. Immature compost contains phytotoxins, which are chemicals that are toxic to plant embryos. Radish seeds are extremely susceptible to these phytotoxins, so you can plant a few in some compost, and if at least 75% germinate, your compost has matured properly.

Using Your Finished Compost
Once you are satisfied that the compost is mature, decide how you plan to use it. Screening it through a ½" wire mesh will create a uniform size that's good for incorporation in garden beds, and the larger and sometimes semi-decomposed pieces can be added to a new pile or used as mulch. You can screen the compost even more finely if you're planning to use it for germinating seedlings.

Whatever you do, always save a shovelful or two of your fresh compost for your next compost pile. The active microbes in the compost will get busy in your new pile helping decomposition get underway, and in a few weeks or months you'll be ready to harvest once again! 

Georgia Nally started volunteering at Sunshine Care in June of this year and completely transformed their compost program.  Sunshine Care (a 24-hour assisted care facility in Poway) has about 1 acre of organic growing fields that supply a main kitchen / building and four houses.  Georgia single-handedly composts about 500 lbs of waste every month that would otherwise go directly to landfills. With the use of three Biostack bins and a worm bin for each house, food scraps, newspaper, yard trimmings from the 28-acre site are composted. The beautiful compost Georgia produces is used on the fields to grow food for meals for residents.

Georgia also helps instruct free composting workshops and assists with the maintenance of the Compost Demonstration Site at the San Diego Zoo.