Deborah Cottingham, Gilroy's Master Composter

Straight from teaching more than 4,000 schoolchildren about composting during Science Days at Gilroy Gardens, Deborah Cottingham talked to Patch about the easiest way to compost.

Deborah Cottingham worked for IBM for 26 years, starting as a software engineer and then moving into technical writing and management. Even before retiring, she began taking classes in horticulture and botany, earning her associate's degree in Landscape Horticulture.

In 1995, Cottingham became Gilroy’s first official Master Composter. Patch spoke to her about her composting work (Part 1) and her love for drought-resistant native plants (Part 2, next week).

Gilroy Patch: You began taking classes in horticulture just because …

Deborah Cottingham: Because I was interested in plants. I’m addicted to plants. When I signed up for my first class at Cabrillo, I wasn’t planning on getting a degree. My first class, “Edible Landscaping,” was such good information, I wanted to learn more.

Patch: How long did it take to earn the AS degree?

Cottingham (laughing): A long time. I must hold the record for length of time required to earn an AS degree in horticulture. I earned my master’s degree in Computer Science much faster.

Patch: This seems a unusual leap—from an MS in computer science to horticulture.

Cottingham: I think horticulture is in my blood. My father had a dream of selling gladiola bulbs, so my two siblings and I spent a lot of time working in the gladiolias. My sister learned to hate gardening, but I still love it.

Patch: How does one become a Master Composter?

Cottingham: The short answer is to complete an application available on ReduceWaste.org, and then go through the training. The program for Santa Clara County began in 1995; I was part of that first class. It's a training program for volunteers who are interested in teaching others how to recycle yard wastes and kitchen scraps at home for use in the home garden. It was started by the county, because encouraging people to compost is a logical way to save money. 

Patch: How does composting save the county money?

Cottingham: In 1989, California passed AB939, which required cities to significantly reduce what they were sending to the landfills. So, yard waste collection and compost training programs popped up. If you think about how big the yard waste collection trucks are—they get maybe 6 miles to the gallon, I'm guessing—and how far they have to drive to collect and haul material, and then the energy required to process large volumes of material, package it, and then haul it somewhere else for resale—then it makes sense to look at composting as a way of reducing spending. It’s an easy place to cut costs and energy use.

Patch: Are a lot of cities in the U.S. working on composting this way?

Cottingham: Composting is as old as agriculture. Home composting is taught and practiced all over the United States—well, really all over the world. As long as humans need to eat, we need to renew our soil so we can continue to grow food. Composting is the easiest, most natural way to preserve and enrich our soil. In some places, such as Seattle, if you didn’t compost, you pay more for your waste pickup service.

Patch: When I told you that I was pretty proud to be composting all my kitchen scraps by throwing them in the green landscape waste bin every week, you hesitated and then said, “But you’re throwing away nutrients that the plants in your yard could use.” You’ve shifted my thinking from “Hey, I’m a good citizen; I don’t throw compostables in the landfill,” to “Wait a sec, I’m throwing away my soil enhancements and then buying fertilizers.”

Cottingham (laughing): I think using the green bins for compostables is a good first step until you’re comfortable with composting in your yard. But I want to tell you about a really easy way to compost that might change your mind about trying it. It’s called "sheet composting."

Patch: OK, how do you do it?

Cottingham: Start at a spot in your yard where you want to begin a new garden bed. In this case (see photos), we started a patch in the center of what used to be lawn. We decided growing tomatoes was a better use than lawn for this super sunny spot. This is a good method for converting a weedy area to a productive garden bed as well.

You don’t need to weed or pull up the grass or anything like that. You start by mowing the area, and then covering it with cardboard. That’s why it’s called “sheet composting”; the cardboard is the sheet. You can also use newspapers or even old cotton towels in place of cardboard; those break down really quickly. The idea is to block the sun to stop the grass or weeds from photosynthesizing.

Patch: And then the organic matter goes on top the cardboard?

Cottingham: Right. I used horse manure, because it has a good amount of nitrogen and it breaks down quickly. We’re lucky, because our neighbors own three horses. Whenever I need manure, I call them, and they kindly bring it right to my yard. 

Patch: It’s a symbiotic relationship.

Cottingham: It’s mutually beneficial for sure.

Patch: So help me understand exactly what to do after the cardboard or towel goes down on what will soon be a lush patch of garden.

Cottingham: Manure is nice but not essential for this process, but you do need sources of nitrogen and carbon to get the sheet compost to decompose. So, pile as many layers of landscape residue as you can gather from your yard. You want grass clippings, leaves, straw, weeds from other areas (but no seedheads!) and perennial prunings. You can ask your neighbors for their yard waste, too, so long as they aren't using pesticides and herbicides. I don't recommend putting kitchen scraps in this pile, though, because you might attract rodents. Then, you thoroughly water the entire pile, which hopefully is at least 12 inches high, and it composts over two to six months. So fall is a good time to start the process. By spring, you have a fabulous garden bed. Google “lasagne gardening” or “sheet composting” for more details, or come to one of my classes.

Patch: So in addition to the sheet composting, you have several composting areas in your yard?

Cottingham: I do. This is a three-section bin that my husband, Art, made. He put wire mesh at the bottom so the earthworms have a place to go when the pile gets hots, and the gophers can't burrow up through the pile.

Patch: Explain to me about the pile getting hot.

Cottingham: The four things you need for composting are air, water, carbon and nitrogen—bacteria—to start the process of breaking down the material, and that action generates heat. If you turn the pile, they'll keep working on the newly exposed material until they can do no more. Then fungi and other microorganisms continue the process on the more woody materials. Eventually, worms, beetles, and other small helpful critters move in. These later phases of the process are cooler than the early phase.  

Patch: Explain to me which materials produce carbon and which carry nitrogen.

Cottingham: Carbon comes from dried organic matter: dried straw, paper, dried leaves, woody twigs. The nitrogen comes from the “living” organic matter: kitchen scraps, grass clippings and from manures of vegetarian animals such as horses, chickens and goats. Don't use cat or dog poop, though.

During the summer, the big challenge is keeping moisture in the pile. I use this high-tech cover to keep in some moisture. (Cottingham shows Patch how she keeps a plain metal garbage can lid on top of the composting pile.) I also use a pitchfork to mix the materials, add air to process, and to add new kitchen scraps into the center of the pile.

You can also start with a smaller compost container like this plastic one. You can buy this from the county for $55. (See photo.) It usually sells for $80-90, so it’s a pretty good deal.

Patch: Do you have to worry about rodents, like rats?

Cottingham: Not really. The heat of the pile keeps them away. As long as you add kitchen scraps into the center of the pile, and stay away from adding meat, fish, oil and dairy, you shouldn’t have a problem with rodents.

Patch: Those things can’t go into your compost pile?

Cottingham: Technically, they would compost, but we don't recommend these materials for home composting.

Patch: Do you add worms to your compost pile?

Cottingham: I don’t add worms. They find it, especially if you add some horse manure or dried leaves (ideally, both).

Patch: Do you teach composting classes now?

Cottingham: I do. I teach in a wide variety of venues, including schools, Earth Week events and community gardens. (For information about composting classes, call the ROTLINE: 408-918-4640.)

Patch: And you also teach stewardship classes?

Cottingham: For nine years I've taught for the “Stewardship for Small Acreages” series. We had a dinner here recently and we tried our best to make it a no-waste evening. We did pretty well, but I suspect a few people snuck trash into their cars.

Patch: That’s kind of an interesting switch. From people not recycling 20 years ago to today when people are embarrassed to admit they have non-compostable trash and have to resort to smuggling it away from a party.

Cottingham (laughing): I’m not sure they smuggled it away, I just suspect that they did. This year, another master composter and I also taught composting at the Natural Science Days at Gilroy Gardens. We had 4,000 kids come this year, some from as far away as Fresno, Santa Cruz and the Peninsula.

Patch: Is there a difference in how much kids know about composting from city to city?

Cottingham: There is. When I have a group of kids from Santa Cruz, and I ask how many of them know about composting, over half raise their hands.

Patch: How many kids from Gilroy raise their hands?

Cottingham: Not as many as I'd hoped, given that we live in an area with a rich agricultural history. The kids who come to Science Days are second- and fourth-graders, so the fourth-graders are beginning to understand the concept, and some even practice composting at home.

Patch: When I was in second grade I had never heard the word “compost.” I think it’s great kids get a chance to learn this. How many people do you think you’ve talked to about compost since you became a Master Composter?

Cottingham: Oh goodness, maybe a couple thousand adults, plus all the kids at Gilroy Gardens. It's a topic I enjoy. Really, I'll talk about composting to anyone who wants to listen. 

Call the ROTLINE for more information about composting classes: 408-918-4640


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