Ferguson: To care for orchids, this is what you need to know

Published 9:51 am Friday, August 13, 2021

A friend recently gave me an orchid, and, not being very familiar with how to care for it, I decided that I would kill two birds with one stone: I’d write an article and, in the process, learn how to care for my own plant.

Orchids, or plants in the family Orchidaceae, include species from a wide range of climates and with a variety of growth habits. Many are epiphytes, meaning that they grow on the surfaces of other plants. Others are terrestrial, or grow with their roots in the soil.

Natural vanilla flavoring is obtained from seed pods of vining orchids in the Vanilla genus. Orchids in the Cattleya genus were historically popular in corsages.

Not all orchids require a tropical climate to grow outdoors. A terrestrial orchid is among the Hammond Research Station’s 2021 Plants with Potential. The Chinese ground orchid (Bletilla striata) has leaves that look somewhat similar to those of cast iron plant, but in the spring, this plant produces attractive purple flowers on approximately 18-inch stalks. Here, it grows well in partial shade.

There’s even an epiphytic orchid, the green fly orchid (Epidendrum magnoliae), that’s native to Louisiana.

If you’ve been given an orchid or bought one, there’s a good chance that it was a moth orchid, or one in the genus Phalaenopsis. These are relatively easy to grow as houseplants and are available with a variety of flower colors and in a range of sizes.

To understand how to care for Phalaenopsis orchids, it may be helpful to know something about how they grow in the wild. These grow epiphytically in humid, tropical climates.

Being epiphytes, they don’t get nourishment from within the plants on which they grow but take up water and nutrients from what collects on the surface of the host plant, and from moisture in the air around them.

As you might imagine, Phalaenopsis orchids need a substrate that is more well-drained than what is appropriate for most houseplants. Special potting mixes for orchids are available. These may contain coarse materials such as tree bark, charcoal, and perlite.

Water demand depends on conditions such as light level, temperature, humidity, and the types of planting medium and container, but watering once or possibly twice per week is likely to be appropriate when orchids are actively growing. Less water is needed after orchids finish flowering.

Water until some drains from holes in the bottom of the container. Don’t allow water to stand in the container. Orchids’ fleshy roots turn from whitish to light green when they’re moist.

At times of year when humidity in the house is low, it may be helpful to increase humidity in the area right around the orchid. Water and pebbles can be placed in a shallow tray and the orchid pot placed on top of the pebbles, above the water. This should be done in such a way that the water doesn’t get into the pot containing the orchid but evaporates around it.

Phalaenopsis orchids grow well when nighttime temperatures are around 65 degrees F and daytime temperatures are 75 to 80 degrees F. At times of the year when temperatures stay above 60 degrees F, one option is to put them in a shady spot outside.

Moth orchids don’t need a great deal of sunlight — this is one reason they’re well-suited to being grown as houseplants — so an east-facing window is often a good option. If you want to grow one in a spot without enough natural light, a grow light can be used. If they don’t get enough light, they won’t flower.

Fertilize Phalaenopsis orchids approximately once per month while they’re actively growing. Water-soluble fertilizers for orchids often have analyses such as 30-10-10 or 20-20-20. Follow product instructions for orchids, and do not overfertilize. Orchids are sensitive to high salt levels.

The bloom period of moth orchids may last for several months. Flower stalks can be kept upright by attaching them loosely to a thin stake that has been inserted carefully into the growing medium.

Let me know if you have questions.

Dr. Mary Helen Ferguson is an Associate Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu, 985-839-7855 (Franklinton) or 985-277-1850 (Hammond).