I’m your garden guide, Mike Brown, “I plant smart and know some dirt”

BY MIKE BROWN

OK, so we probably all know some dirt, but do you know real dirt, as in garden dirt? In case you don’t, then I’ll pass on some helpful advice that will help you have a fabulous and envious dirty little garden with terrific soil! But first, here’s a quick lesson on the difference between dirt and soil. Dirt is a noun that can be used three ways in conversation: dirt as grime, dirt as soil, and dirt as gossip. Many of us use the words dirt and soil interchangeably, but gardeners and farmers use the word soil, since “dirt” implies something that needs to be washed. Like having your mouth washed out with soap for saying a bad word as a kid. Soil is also a noun and can be used three ways in conversation as well: soil as earth, soil as dirty, and soil as territory. But to be politically correct in garden jargon, use the word soil when making reference to what you are digging in or amending.

Soils are variable and contain organic matter, minerals, rocks, and sand. Many soils contain all or none of these elements in differing amounts and often need amending to nutritionally benefit your garden. Sandy soils, for example, allow water and nutrients to filter through rapidly. On the other hand, clay soil retains water, causing it to pool at the surface of the ground and can accumulate around the roots of plants for long periods of time. Soils that fall between these two extremes are called combination soils. A good soil contains mineral elements and organic matter (that is broken down through a process called decomposition).

All areas of the globe have different soil profiles; for example, grasslands tend to have a thicker top profile of organic matter and a thin profile of compound minerals; whereas desert soils have a thin top layer of organic matter due to lack of decaying plants. Soil in our garden can be a combination of different types and also can change the farther you go beneath the surface. The topsoil is the most active layer of soil. This is the area where you find organic matter, insects, and earthworms, all of which are vital for the health of the soil. The second layer of the soil is where you will see visual changes, such as color and texture. These two levels are the most important in gardening because, with the exception of trees, we normally do not have to excavate any deeper than several feet. Having some basic soil knowledge will increase your chances of having a healthy garden. What ever your soil type, there are prepackaged soils available at your garden center—topsoil, cactus mix, and organic composts—to help you prepare your garden before planting.

It might come as no surprise to discover that the soil on your property will vary in texture, color, and quality. This is especially true if you have purchased a home in a new development. These soils tend to be disturbed soils and more often than not, a layer of topsoil is brought in after excavation of foundations and installation of pipelines. Soil erosion can be a big problem from rain and wind since most new housing developments have nothing to hold back the top layer of soil. Pay attention to how water runs off your property. Does it pool in certain areas? Having water pool could mean you have a clay base beneath the topsoil (this will need to be amended with organic matter and or sand depending on plant requirements). It could also be a sign of large rocks, discarded building materials, or an old concrete driveway or sidewalk. These objects may need to be removed.

If you suspect your soil is clay-based, here is an experiment you can try to see how quickly it drains. Dig a hole large enough to hold a one-gallon container, fill it with water from the garden hose, and let it drain. If it drains in less than an hour, you have a sandy soil base; if it takes between two and four hours, then you have a loamy soil (which is the jackpot for gardening); if it takes more than four hours, your soil base is clay (which means poor drainage).

There are plants that will do well in clay soils, such as azaleas, dogwoods, and forsythia, and you will not have to amend. For sandy soils, the drainage will be rapid and so the water will percolate fast (think of water filtering through coffee grounds) and the roots will not absorb as much water. You would not want to put succulents in clay soils, as this soil holds too much water and the roots would rot. You would not want to put tropical plants in sandy soils as they require more water at the root base.

Amending soils can be a major project, especially if you are planting your entire garden. You will need to remove existing soil and bring in the amending soil. There is some controversy on amending soils, especially since most plants “outgrow” the amended area eventually. I usually amend to give my plant the best growing start. As an alternative to spending time and money amending soils, you can choose plants that are native to your environment. But if you chose exotics or are planting a vegetable garden, you may have to build a raised bed with organic soils purchased from your nursery.

Now that you’ve had your fill of dirt, go out and get dirty in the garden! You can always clean up later.

Mike Brown is a garden and landscape designer in Los Angeles. Please send your questions and suggestions to him at greengardenguy@yahoo.com.