How do you correct alkaline soil? What plants do well in that soil? —Debra Clarke, Las Vegas, NV
Desert areas like yours often have alkaline soil (soil with a pH higher than 7.0). It’s easier to choose native plants that are well-adapted to local conditions than to fight nature to acidify your soil. Plant choices depend on where you live and how alkaline your soil is.
Alkaline-tolerant perennials include Russian sage (Perovskia atriplicifolia, Zones 4 to 9), globe thistle (Echinops giganteus, Zones 4 to 8), and Oriental poppy (Papaver orientale, Zones 3 to 9). For more choices, check with local nurseries.
To make soil less alkaline, incorporate elemental sulfur or sulfur-containing fertilizers such as ammonium sulfate or iron sulfate. Granular sulfur is cheapest, but also works slowest. In fact, reducing soil pH is always slow—it often takes several years. Your success will depend, too, on what type of soil you have. It’s easier to acidify sandy soils than heavy clay soils.
Incorporating organic matter such as peat moss or cottonseed meal will help acidify the soil. In a pinch, you can spray plants suffering from iron chlorosis (a condition in which high soil pH causes leaves to yellow and eventually turn brown, particularly between the veins) with liquid chelated iron. It will give them a quick green-up, but it’s a temporary fix.