Cactus seedlings in the store look alike, so the one you select could be a baby 20-foot saguaro or an Echinopsis that stays less than a foot and blooms like crazy. Of course you can’t tell at such early ages when accurate labels are rare. Yet this is how most cactus are sold outside their territory of the desert Southwest.
The Cactus family is enormous, and in a constant state of flux as DNA more accurately tells us who is truly related to whom. It’s like a monster genealogy project that could blow up many old family trees. This is why the names are always changing.
Cactuses are surprisingly diverse, distributed from Canada to Patagonia, changing as the terrain and climate varies. From hot and tropical on the Equator to high and dry in the Andes to our own cold winter deserts, there’s clearly a very wide range of climatic preferences. That means there are tropical cactus that want water in the air or they die … quickly. There are jungle and forest cactuses that grow in partial shade. And yet we tend to treat them all as though they originate in the middle of the Mojave Desert.
For example, perched on sheltered rocky slopes and cliffs of tropical Mexico, the Gymnocalyciums are kept evenly moist in the shade by dripping springs and Caribbean rains.
Most potted cactus die in winter. This is because they’re dormant and look dry as moisture gradually decreases inside them over many dark months. They won’t be so fat when they hunker down to wait for rain. Folks always think this dry look means they need water, but when dormant, they don’t. Introduce moisture to this plant’s root zone in the winter and it just sits there without evaporation. This starts rotting the fine roots, then rot travels up larger roots into the plant itself. The ultimate result is a soft gooey mess inside come spring. When spring comes they begin to suck up water to fuel reproduction and the growth spurt that follows flowering. The hotter and longer the days, the faster they grow.
Cactus bloom spring and summer, which is the best time to buy so you know the flower colors you’re getting. A lot of them bloom white, so if you want big bold color, by all means buy in bloom. Once you have found the one, then follow these tips for a beautiful carefree summer garden accent for a sun filled porch or patio.
— Choose a pot that’s wider than it is deep, because many cactus root shallow to catch every drop of rare rain that falls. They hold water in their bodies so they don’t need a big root area like ordinary plants.
— Use cactus soil. If you don’t have it, mix of 50 percent peat based potting soil and 50 percent sharp sand for optimal drainage and water holding capacity.
— Large drain hole. Choose pots made for cactus such as the standard terra cotta “pans” that feature a dime-sized drain hole to ensure maximized drainage. Smaller holes easily clog and that’s all it takes to start rotting the roots. Specialty pots with a multitude of holes are often the best.
— Avoid saucers. We use saucers to protect surfaces or tables, but they are dangerous to cactuses. Saucers can hold moisture against the drain hole so there’s no space to create a vacuum to draw water down and out. An alternative is to use pot feet or broken tiles to raise the pot up enough to create a similar dry space underneath.
During the growing season, water your cactus. Most die because beginners believe they don’t need much (if any) water. But give them a nice pot, proper drainage and soil this summer, then treat them properly over winter to enjoy these curious geometric plants for many years to come.
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Maureen Gilmer is an author, horticulturist and landscape designer. Learn more at www.MoPlants.com
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