While skimming a magazine from England called Permaculture, I found an article about mounding. The article described how to build mounds in your garden and what materials to use. Over time, the soil becomes richer from the decaying materials. Also, the sides of the mounds provide more space to plant. I realized that I have already done this in my own garden.
When I removed my back lawn many years ago and replaced it with mounds, i used the dried turf from the lawn. I turned the sod upside down for the base of each bed, then proceeded to build the beds up with mulch from my own yard; branches, bark and trimmings. On top of the whole thing I added compost and some garden soil.
These beds were created 20 years ago and are still looking good. I have some major plantings on them, such as small maple trees and lily of the Nile (Agapanthus). Annually, I add compost and dried leaves to enrich the soil.
I also created a mound when I gave up on my huge walnut tree. The squirrels were stripping it and dropping unripe walnuts everywhere, including into my fish pond. After much consideration i had the tree removed.
After the stump was out I started to fill the depression with organic materials from my yard. The first layer was sticks and stumps from small prunings around the yard. Then I added leaves and other garden waste and piled soil on top of the whole thing. Since I planted figs on this area, I call it Fig Hill. It also gets annual composting and other soil added to keep the height.
The sticks and other organic materials that I put in these mounds act like a sponge, absorbing water and holding it for the plants. If you have soil that does not drain well or is hard to work, mounds will help with both of these problems.
With both of these experiences, the results repaid the work. Now is a good time to start such a project in your own yard as you prune and clean up in your garden.
As I learned from the magazine article, one approach is to dig long trenches and then fill them with logs, branches, leaves, grass clippings, straw, cardboard, black and white newspaper, cured manure, compost or other available materials. Then you top it all with good soil. Water well and let the soil and materials start to decompose and settle. Then you are ready to plant vegetables or flowers in your mounds.
The organic content of the mounds gives off heat as it decays and keeps the soil warmer. And the decomposing wood gives off nutrients for years. Hard woods will take longer to decay than soft woods.
An added benefit of the mound method is that it doesn't require tilling. No-till gardens are better for the creatures that live in the soil, like earthworms, so, ultimately, they are better for soil health.
Mound gardens also mean less bending for the gardener.
The article recommended constructing steep beds to avoid compaction from foot traffic. Steep beds create more surface area in your garden for plants, and the height makes easy harvesting. The greater the mass, the greater the water retention.
Some of the beds shown in the article had straw on the top and sides to hold the materials in place. Others had wire sides with plants inserted between the wires. One gardener used shipping pallets to hold everything in place with plants planted between the slats.
Next workshop: “Sustainable Vegetable Growing” (Four-Part Series) on Sundays February 23, March 1, March 8 and March 15, from 2 p.m. to 4 p.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. For more details & online registration go to Online registration (credit card only) or call 707-253-4221.
The UC Master Gardeners of Napa County are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website (http://napamg.ucanr.edu) or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.
By Penny Pawl, U. C. Master Gardener of Napa County
I just built an African keyhole garden and I'll bet you are wondering what that is. The African keyhole garden was designed by CARE in Zimbabwe during the mid 1990s to encourage people to grow their own food. The design relied on materials that were close at hand—such as bricks, stones, branches, hay, ashes, manure and soil—to create an easy-care garden for disabled people.
The plan became so popular that many Africans began growing kitchen gardens. A so-called keyhole garden bed has a dead end opposite the opening. At the dead end is a compost bin. More than 20,000 of these have been built in Africa.
The Texas Master Gardener Association has held a number of workshops to promote this type of garden. They have also standardized the plans. Their version is a six-foot-wide garden bed with a twelve-inch-wide bin made of chicken wire in the middle. The gardener fills the bin with compostable material such as moistened newsprint, cardboard, dead plants, kitchen waste and red wiggler worms, the same components of a worm bed. The concept is that the worms will gradually decompose the material and their castings will nourish the soil and plants around the bin.
For mine, I decided to use an old garbage can with holes drilled in it. The garbage-can lid keeps out pests and any creature looking for a warm nest. I created the planting bed with building blocks set three high and cemented in place.
Alas, I had a big problem with gophers, and I needed to win that battle. So this fall, when it was time to rework the soil, I put a layer of hardware cloth on the bottom. The hardware cloth helps to keep the gophers out. It won't last forever, but it will foil the varmints for a few years. Then a mixture of clean cardboard and soil was placed over the hardware cloth. Since the bed was already in a square keyhole shape, I added the garbage can and put soil around it to hold it in place.
I fill this garbage can with the same things I put in my worm compost beds, including red wiggler worms. I have been watering it and feeding it for a few weeks to try to get it working. Eventually, the liquid and castings from the worms and other insects will work its way into the new bed areas and fertilize the soil from below rather than from on top.
Tall garden beds that have compost bins built into them are called "banana circles" by permaculture specialists. I plan to incorporate banana circles in future garden beds.
When you plant your keyhole garden, aim for variety of plants in small groups as opposed to a single crop. Some vegetables do not do well in this type of situation, such as tomatoes, potatoes, peppers, eggplant, corn and squash.
I like the concept of the keyhole garden so much—relying on a compost bin in the middle to feed the plants around it—that I plan to try it in beds without the keyhole and see what happens. These beds will need to be cleaned out and refilled every four to five years.
Keyhole gardening techniques are often used in permaculture design. For more information, consult the North Carolina State University Extension site (https://content.ces.ncsu.edu/extension-gardener-handbook/appendix-d-permaculture-design) or the Nifty Homestead site (https://www.niftyhomestead.com/blog/keyhole-garden/). You will also find more advice and books on the topic online.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
