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Botanical and Test Gardens


Compost is the decayed organic material that provides valuable nutrients to garden soil. Compost improves the soil structure, texture, and aeration of local soils. By adding compost to the soil you improve the fertility of our infertile desert soils, as well as reduce the need for commercial fertilizers. The organic matter that is provided by compost feeds the microorganisms in the soil. In addition, compost moderates the soil's water holding capacity by loosening up a clay soil and helps a sandy soil retain water.

When making a compost pile, be sure to use only plant wastes. Never add bones, grease, meat or plastic materials because these will not break down properly. Do not use eggshells or ashes, as they will raise the pH of the local soils. Avoid adding weed seeds, plants that are infested with insects, or plants that show signs of disease. Materials to be composted are: leaves, straw, grass clippings, shredded bark, coffee grounds, tea bags, produce waste, vegetable and fruit peels. Do not use any plant material that has been treated with an herbicide.

Compost makers

Compost can be turned into the soil as a soil amendment or used on top of the soil as mulch.

There are commercial compost makers available as displayed in our Demonstration and Test Gardens, for your perusal but it is not necessary to use one to make compost successfully. We have a selection of commercially made compost makers for your perusal.

Steps to Building a Compost Pile

  1. Locate the pile in an inconspicuous spot
  2. Place a layer of coarse material such as straw several inches thick on the ground for drainage
  3. Place a layer of material to be composted about three inches thick
  4. Place a layer of soil (or compost from a previous batch) in the initial mix only
  5. Place a layer of dry material like shredded leaves, wood chips, or shredded paper, about six inches over that
  6. Water thoroughly
  7. Aerate the pile by using a fork or shovel to mix it up every few days

Repeat steps 3 through 7. Omit step 4 after the initial mix.