GOT DIRT
Ann Higgins
In a previous post for this column about plants that add interest to the winter garden (“Winter’s Gifts,” February 17, 2011), I mentioned the holly bush and its beautiful red berries. A reader responded that she had purchased both a female and a male plant, as required to produce berries, but even after a couple of years there were still no red holly berries. What else did she need? Join me in digging a little deeper for an answer.
What does it take to ensure a tasty vegetable, a magnificent tree, or beautiful holly berries? The root system of any plant needs to be nestled in an environment that is composed of all the right stuff. What is that stuff? Dirt. Dirt is everything when it comes to the success or failure of a garden or an individual plant. Dirt. The stuff we created mudpies out of when we were little kids. Dirt. Under our feet from the time we stand up. Dirt. We’re willing to spend large sums of money to soak in it. Dwellings are built with it. Dirt. We get on our knees and kiss the ground when returning to a cherished place.
Dirt is soil. Soil is broken-down rock, mineral particles composed of sand, silt, and clay. It is air and water, organic matter, and microorganisms. The physical properties of soil are color, texture, structure, drainage, and depth. But all dirt is not the same. Living along the Rio de Flag, we have rich dark brown soil, but at our prior property about a mile from here, we had rock. Fellow gardeners on the east side of town contend with lots of clay. So we need to know our dirt.
Look at the color. If the dirt is light brown, it’s probably low in organic matter. Dark brown indicates high in organic matter and black dirt means very high. The texture of the soil is determined by the amount of sand, silt, and clay. Jan Busco’s book “How to Get Started in Southwest Gardening” (written with Rob Proctor) suggests learning more about your soil by simply digging up a trowelful, placing it in a jar of water with a top, shaking until dispersed, and waiting until it settles into layers. At the top will be a shallow layer of organic matter. Beneath this is fine-textured clay, then mid-sized silt, and at the bottom a layer of coarse-textured sand.
Soil with more than 40% clay particles is considered clay. It will hold a lot of water, get sticky, and drain slowly. Sand contains about 70% sand particles and drains quickly. More equal proportions of sand and clay have intermediate water-holding capacity and properties. To check drainage, dig a hole. Fill it with water and after it drains, fill it up again. Check it the next day; if the water is gone it has good drainage.
Almost all soils benefit from adding organic matter, often in the form of composted materials or aged manures. Compost helps loosen up clayey soils and can provide structure to sandy soils, as well as providing nutrients and microorganisms to all soils.
One last factor in knowing your soil is the pH, a measurement on a scale from 0 to 14, with 7 being neutral. Below 7 is acidic and above 7 is alkaline, or “base.” In Flagstaff we tend to tip from neutral toward alkaline. And this is where we return to the initial query. Why no holly berries? For a holly to produce fruit, there must be both a male and a female plant. Our reader purchased both. But now we find that hollies prefer soil on the acidic side, but Flagstaff soils are generally on the alkaline side. Therefore, if we change the pH by amending the soil with ammonium sulfate (check with a local nursery), there’s a better chance of seeing some beautiful red berries.
Now that you’re a little more familiar with dirt, perhaps just for the fun of it you can make some mudpies, squish it between your toes, and maybe even rub a little on your skin.
Ann Higgins is a Master Gardener and teaches yoga in Flagstaff. Dana Prom Smith edits GARDENING ETCETERA, blogs at http://highcountrygardener.blogspot.com, and can be emailed at stpauls@npgcable.com.
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