Most of us think it’s simple–soil is what’s on the ground and dirt is what’s under your fingernails, but seasoned gardeners know that it’s soil that makes plants sing’it’s the medium that supports crop plants, physically and biologically. Horticulturalist Don Delano, who oversees the 500-acre Pomona landscape at the Pomona Fairplex, is an expert on soils and fertilizers. He will talk about potting soils and fertilizers and bring samples to the Palisades Garden Club meeting on Monday, January 7, 7:30 p.m. at the Woman’s Club, 901 Haverford. Most potting soils are based on the Cornell mix, so named for having being developed at Cornell University. As soil is an agricultural product, it is subject to U. S. Agricultural regulation. The Cornell mix tends to be stable and is the standard throughout the country. ‘Most potting soil is made up of 20 to 30 percent inorganic material’sand or fine gravel’and 70-to 80- percent organic material’decomposed vegetation such as peat moss, pine shavings,’ Delano says. ‘Potting soils are fortified with nitrogen, potassium and phosphorous.’ Although it may sound counterintuitive, Delano says that coarser soils are better suited for smaller pots they allows for an easier flow of air, nutrients and gases. Finer material soils are better suited for larger pots as they absorb the organic plant nutrients, gases and water, which are important for plants. In discussing soils, Delano mentioned words such as Vermiculite an composed of. Vermiculite is processed mica, often used in small pots as it holds water and attracts nutrition. The disadvantage, when used in large pots, is that it tends to compress and impede circulation. Perlite or sponge rock is often used in larger pots because it doesn’t break down and allows good air circulation. The bad news is that over time, it tends to float to the top of the pot like white beads. Delano says that with our heightened attention to the environment one of the biggest shifts in potting material is from peat moss to coir, a byproduct of husking coconuts. Peat is an accumulation of partially decayed vegetation matter that forms in wetlands or bogs. It forms deep below the surface, often going down to bedrock, Delano says. In digging for peat, miners strip down through virgen forests to rip it out. It will take another 100 years to build up even a layer of peat 6-7-inches deep. So agriculturalists are beginning to use peat from Finland that necessitates digging just about 20 inches or so down to the bogs, thus allowing the material to replenish faster. Coir is also recommended as a substitute because it is free of bacteria and fungal spores and is sustainably produced without the environmental damage caused by peat mining. Delano brings to his audiences, not only 18 years of teaching experience at Cal Poly, but also his expertise putting on the floral garden shows at the Pomona Fair. He has also been in charge of entire landscape at the fair for the last 16 years. The Garden Club meeting is free and open to all. Contact: (310) 450-6901.
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