Sonoma County Master Gardeners Advice to Grow By: Composting kitchen scraps

Phyllis T. writes: I’d like to save my kitchen scraps to make compost. Can you please tell me how to do this?

Answer: Making your own compost at home can be a fun way to recycle your food scraps and yard trimmings into a rich soil amendment. Having healthy soils is the first step to having a beautiful garden, and compost is an easy way to improve your soils at home. All you need to be successful is a covered container in your kitchen for the right kind of scraps and a place in your yard for a compost bin or pile.

Every year during the first week of May, we celebrate International Compost Awareness Week. This year the theme is “Grow, Eat … Compost … Repeat.” Now is the time to get in the composting spirit and give back to your garden all the good things it deserves. Composting at home saves resources and can help fight climate change. When we keep our fruit and vegetable leftovers at home, we limit the production of methane gas from food waste in landfills.

A landfill is an environment that has little to no oxygen. When we send compostable material to landfill it degrades anaerobically, without oxygen, and produces methane gas. Methane gas traps at least 28 times more harmful radiation and heat than carbon dioxide, according to the EPA.

Getting started with composting is easy. You need food scraps and woody plant trimmings, which we call greens and browns. Greens include fruit and vegetable scraps, grass clippings, wilted flowers and even coffee grounds and eggshells. Greens are a source of nitrogen and are generally moist. Browns include dried leaves, shredded cardboard, wood chips, dried grass and straw. Browns are a source of carbon and are generally dry.

We need a mixture of half green (nitrogen) and half brown (carbon) material to have an active compost pile. This can be expressed as 30 parts carbon to 1 part nitrogen.

Cut all your materials into small pieces; less than 1 inch is ideal. Mix these materials together using a tool like a spade or a pitchfork. Next, add water. A healthy compost pile should be neither dripping nor dry but damp, like a wrung-out sponge. You need to turn your pile every few days to introduce oxygen, especially when you are just starting a new pile.

It’s best to put your compost pile in a space that is at least 3 feet by 3 feet by 3 feet — the minimum amount of space and material you need to ensure your pile gets hot. Reaching a hot temperature, around 120 degrees, is important in a backyard compost pile in order to kill weed seeds and pathogens. To reach this heat level, the compost pile needs three things: plenty of carbon and nitrogen material, the right moisture level and oxygen, introduced by active turning.

Keep certain animal products out of your backyard compost, like meat, bones, grease and dairy products. Manure from grass-eating animals, such as cows, rabbits, sheep and horses is OK, but do not compost human waste or pet waste from carnivorous animals, like cats and dogs.

If your compost pile isn’t warmer than 120 degrees, do not put in diseased, invasive or seed-bearing plants. Bermuda grass, oxalis, burclover, wild oat and Himalayan blackberry are all undesirable. You can put those materials in a municipal green waste bin that is picked up by a trash hauler or put them in a designated area on your property to dry in the sunlight.

You can use sight, smell and touch to tell when your compost is “ready” or finished. Finished compost should look like soil — dark brown and crumbly. It should smell like soil and maybe even have a sweet smell, but never sour. It should not be hot to the touch but the same temperature as the outside air. Individual items like sticks, corn cobs or avocado pits can be sifted out of finished compost and put back into your pile since they take longer to decompose.

Finished compost can be used in raised beds, under fruit trees, in pots and really anywhere you want your plants to grow beautiful, healthy and rich with nutrients. You can make and use compost all year. The best time to give your soil that extra boost is in the fall when the rains help incorporate the nutrients into the soil. Happy composting!

May in the Garden

Ready? Set? Plant! It’s time to plant all summer veggies — beans, cucumbers, eggplant, kale, lettuce, melons, peppers, squash and tomatoes.

Add edible flowers to your garden for a pop of color and to attract beneficial insects that pollinate the garden and provide an ecological balance against harmful pests. Common edible flowers include carnations, violas, lilacs, roses, lavender, marigolds and nasturtiums. You also can enjoy the flowers of herbs such as rosemary, basil, thyme and sage.

It’s not too late to plant summer-blooming bulbs like dahlias, crocosmia and gladiolas and summer annual flowers like begonias, marigolds, Gerbera daisies and sunflowers.

Deadhead and prune azaleas, rhododendrons and camellias after they have finished blooming. To remove the spent flowers of the rhododendrons, use pruners or two fingers and cut just above the two new leaflets. During the spring and summer, feed these shrubs monthly with a balanced organic fertilizer formulated for acid-loving plants.

Prune all spring-flowering trees and shrubs when bloom is past.

Useful links:

Edible Flowers: bit.ly/3uTMFMx

Methane and Climate Change: bit.ly/3v45QTS

Contributors to this week’s column were Master Composter Jennifer Roberts, Pat Decker, Karen Felker and Debbie Westrick.

Send your gardening questions to scmgpd@gmail.com. The UC Master Gardener Program of Sonoma County (sonomamg.ucanr.edu) provides environmentally sustainable, science-based horticultural information to Sonoma County home gardeners. The Master Gardeners will answer in the newspaper only questions selected for this column. Other questions may be directed to their Information Desk: 707-565-2608 or mgsonoma@ucanr.edu.