By now, anyone who has tried to dig or work in our Bay Area soil knows about clay or adobe. Those poor souls who have emigrated from the Midwest where you could sink a shovel into its hilt are shocked by our heavy, dense soil. Those of us west of the Sierras are beneficiaries of ancient geology. Long before dinosaurs, much of the Pacific Ocean extended to about what are now the Rocky Mountains. Over millions of years, material eroded from the mountains settled to the bottom of the ocean with the finest materials (clay) coming down last and landing on top of all the other material. Mixed in with the clay were all sorts of shellfish (clams, oysters, snails, etc.) which died and left their shells to decompose in the clay. Later, the land lifted and the ocean receded leaving the soils we now have in the Bay Area, Sacramento Valley and the San Joaquin Valley. These are among the richest soils in the world; witness the crops produced in our two big valleys and the Santa Clara Valley (before it was paved over). The clay soil has every possible mineral a plant needs for growth but it’s just too darn hard to work into a decent garden.

To make our heavy clay and adobe soils more workable, a considerable amount of organic matter in the form of decomposed plant material must be mixed into the top eight to ten inches of the clay soil. The organic matter continues to decompose when it is mixed with the clay and moves in between the clay particles forming a looser, friable mixture. A good workable recipe is to scatter ten pounds of gypsum per 100 square feet, Master Start fertilizer at two pounds per 100 square feet, and two inches of organic matter over the entire area. All of the ingredients are then Roto-tilled or dug down to a depth of eight to ten inches. The gypsum acts chemically with the clay to help separate the particles. The fertilizer provides extra nitrogen to help the soil microbes break down the organic matter.

The organic matter can be purchased in bulk or bags such as Gold Rush and spread out as needed. Or the home gardener can make his/her own organic material in the form of compost. Compost in its simplest form is merely partially decayed vegetation. When leaves, grasses, twigs and such decompose normally in the forest, we call it humus and it gradually mixes into the upper layers of existing soil. This is what we wish to duplicate in our home gardens.

Home composting can range from an ultra-simple to a highly refined procedure. The ultra simple procedure consists of accumulating all the household and garden plant materials in a vacant corner of the back yard. Leaves, pine needles, small twigs, grass clippings, weeds, vegetable discards, and even egg shells are all placed in a pile. A bit of garden soil is scattered on the pile, to occasionally provide the microbes needed to do the decomposing. If the pile is left alone, it will take one or two years for all of the ingredients to decompose to a useable size. Material is constantly added to the top and removed from the bottom. With a bit of help such as stirring the pile every week or two and sprinkling a spray of water on the pile, the time can be cut to four to six months.

The finished compost can be added directly to the soil or collected and stored until there is enough to treat a large area. Adding a little at a time to the surface as mulch is a valuable procedure because the compost will gradually find its way into the soil.

(Continued next week --- more refined composting procedures, problems, compost as fertilizer.)

Named after Euphorbus, physician to the king of Mauritania, this robust, sun-loving genus includes the familiar Poinsettia and is over 1600 species strong. Most species have a poisonous milky sap and softly colored bracts that surround subtly defined flowers. Autumn watches their narrow green leaves turn shades of red, orange and yellow. Some attributes of the genus are their drought tolerance and their suitability for xeriscaping, rock gardens and containers.

Euphorbia purpurea--Purple Wood Spurge

The Spurges are becoming quite popular among gardeners. This colorful selection has handsome burgundy-purple foliage, perfectly setting off the clusters of bright greenish-yellow flowers that appear in mid-to-late spring. Plants remain evergreen in areas where they are hardy, developing black-purple tones in the cooler months. Flowers appear on old wood, so prune plants back lightly right after flowering it they need it. Caution: skin and eye irritant/toxic if eaten.

Euphorbia Blue Haze--Milkwort

Crowned by yellow-green flower heads, the attractive, blue-gray linear foliage is densely arranged in a compact and bushy evergreen mound. Blooms July–September.

Euphorbia Tasmanian Tiger (Variegated Spurge)

This succulent perennial/ subshrub has narrow foliage with distinct variegation of green centers with white/cream margins. Growing to 3 feet tall and then topped with broad heads of flowers in summer, that are of the typical chartreuse color but with the bracts also plainly margined with white. A stunning sight especially when combined with bold dark foliage plants like Phormium Dark Delight. Plant in full sun to light shade in a well drained soil and irrigate regularly to occasionally. Hardy to 0-10 degrees F. This plant was a seedling discovered in Sally Johannsohn's garden in Hobart, Tasmania, in 1993. The upright 3 feet tall stems are clothed with blue foliage edged in creamy white.

Snapdragons are a particular favorite of children who like to pinch the tiny individual blossoms and make the "dragon mouth" open and close. Their large, blossom-laden flower heads are faintly fragrant and come in a wide assortment of bright colors. The vertical flower spikes, opening gradually from the bottom to the top, are available in two heights: dwarf varieties grow to about 10 inches while the taller types grow to a height of 18-24 inches.

Snapdragons make excellent cut flowers and excel in beds and at the front of borders. Snapdragons flourish in well-fertilized soil and full sun with average watering. Snapdragons bloom from late summer through fall.

Reynold’s GeoBin™ is a low-cost, easy solution to your yard waste problem. It replaces the unsightly pile in your backyard with an attractive, functional container. This adjustable bin will hold over 14 bushels of perfect composting ingredients. GeoBin™ can take grass clippings and leaves and turn them into a rich soil conditioner for use in your gardens.

The GeoBin™ is easy to assemble, easy to fill and easy to maintain. Made of rugged, lightweight plastic, it's ready for use in minutes. Due to the generous number of air holes and open top, the composting process takes place very quickly. Don’t let the simple appearance fool you; this is a hard-working tool that should be in every backyard.

RapiTest Compost Thermometer

Using organic compost in your garden helps balance beneficial microbes, improve soil texture and fertilize the plants. Composting at the proper temperature (110 - 160 degrees F recommended) hastens the decomposition of your kitchen or yard debris, giving you a finished product more quickly. The Rapitest Compost Thermometer helps managing your composting process more simple. You use it to test the internal temperature of the compost site, which in turn, helps determine when to add organic matter, moisture or to turn the pile.

The face of the Rapitest Compost Thermometer is to easy to read, registering a heat range of 0 - 220 degrees Fahrenheit. It has a sturdy 19" stainless steel probe and dial casing for durability and easy clean up. No batteries needed.