Plants out of their region may fail or take over

Q: What is a fairy castle cactus? - Courtney, Kingston

A: The plant, Cereus tetragonus, is a small succulent with spines that blooms infrequently. It is native to North America but is only suited for cultivation outside in USDA zones 10 to 11 (most parts of the mid-Hudson region are in zones 5b, 6a and 6b). It is a very slow-growing plant that will eventually reach 6 feet tall.

The stems on fairy castle cactus plants are five sided with woolly based spines along each plane. The limbs are a bright green, turning woody and brown with age. Over time, different branches are formed, which slowly lengthen and produce an interesting silhouette. Fairy castles are often sold with bright straw pink or yellow flowers hot-glued to the spires to add color. Many growers prefer to gently remove the fake flowers, or allow them to fall off as the cactus grows.

The fairy castle cactus rarely blooms. Cacti need perfect growing conditions to produce flowers and the plants in the Cereus family bloom at night. Fairy castle cactus flowers are large and white and usually will not occur until the plant is 10 years old or more.

They are used to downpours followed by long dry spells. Soak a fairy castle’s soil and let it completely dry before watering again, about one or two months. Over-watering is the easiest way to damage a cactus. To aid drainage and prevent rot, place it in a large glazed clay plot with a tray. Rotate the pot every few months to keep the cactus from growing crookedly toward the light. Use a 50/50 mixture of potting soil and sand to mimic its natural environment. Place the little cactus in a bright, sunny location that is away from drafts or air conditioning. Enjoy but don’t touch the spines!

Q: What does the term invasive plants mean? - Bob, Woodstock

A: This term is a misnomer. When folks say invasive plants it actually means opportunistic. When we call them “alien invaders” it connotes something even worse. There are two kinds of opportunistic plants, native and non-native, and even those terms are relative to how far back we want to go to label something native. There are also those lovely exotic hybrids we love that come from other countries but have been here for centuries. Some of those have a tendency to be opportunistic. Ground covers are a good example, and strawberries spread and can take over as well as anything in the mint family. We like them, and that changes the lens of how we view them. Back in the 1950s many of today’s plants that are now listed as invasive were used as conservation plants to hold soil or spread easily in disturbed areas along roadsides.

Our human activity has increased the spread of many native and non-native species by changing the environment, disturbing the soil structure, planting large monocultures of one crop, and the agricultural practices that break up the natural soil organisms. We brought many of the non-native plants here, whether knowingly or as hitch-hikers. Japanese knotweed was brought here as an ornamental and flourished here because its natural environment is the sides of volcanoes. Japanese knotweed is also very high in resveratrol, a cancer-fighting compound, and a bio-fungicide for cedar-apple rust has been developed from it.

Millions of dollars are spent each year to eradicate or “control” invasive plants. If we can accept responsibility for changing our environment and growing just one native plant or looking into the value of the nonnatives we will be doing something.

Dona M. Crawford is the Master Gardener coordinator for Cornell Cooperative Extension Ulster County.