“Why is the soil here so orange and sticky?” This is a common question from people who moved from other parts of the country to the Carolinas. I admit, writing about soil is not nearly as much fun as writing about plants, but soil is, after all, a key component to gardening success. Bear with me while I share the basics.

Soil particles are either sand, silt or clay. If you’ve ever been to the beach, you know that sand particles are large enough to see without magnification. Sand allows water to flow through very easily and does not retain nutrients. Silt soils have a powdery feel to the touch. A pure silt soil is rare. Clay soils have the smallest size particles, not visible without magnification. Clay is smooth to touch. When clay soil is wet, it is almost gummy. You could roll it into ropes, almost like kids’ play-dough. Once clay soil is thoroughly wet, it takes a long time to dry out. Once it dries completely, though, it requires a lot of moisture to saturate. The bonus of clay is that it holds nutrients well. No need to add fertilizer every few weeks.

Saturated clay soil should never be tilled or dug until it has dried out a bit. If your shovel leaves shiny sides to the hole you’ve dug (almost looks greasy), delay digging a day or two. Here is something that seems counterintuitive: If you want to make it easier for your plants to put down deep roots, DO NOT add sand to your clay soil, thinking that the sand with “lighten” the clay. Adding sand will create a nightmare soil that hardens into something similar to adobe (“brick”). Instead, add organic matter – it can be compost, leaf mold, ground pine bark (often labeled “soil conditioner”), aged manure, or mulch. Organic matter improves drainage, adds nutrients, and provides an environment for good bacteria. It is almost impossible to add too much organic matter, because it is constantly breaking down. The warmer the climate, the faster the breakdown. It works best if tilled into the soil, but if you cannot dig it in, throw it on top of the soil. Top-dressing your beds with a couple of inches of organic matter every year will repay you with a lighter soil and healthier plants. As much as I love the look of flower beds dressed with pine needles, they don’t break down and improve the soil nearly as well as ground bark mulches.

Back to the question – Orange soil is due to iron oxidation, another name for rust. It’s almost impossible to launder stains out of the knees of your khaki garden slacks, so invest in a comfortable gardener’s kneeling pad.