Yes, everyday gardeners, it’s time to start thinking about what we can grow indoors over the long winter. So I thought I’d write my last column of the season on how to grow orchids. By now, you’ve probably noticed that you can buy orchids just about anywhere. Stacked up with all the other impulse-buy items not far from the checkout lane at places like Target and Home Depot — even the grocery store — amazingly beautiful orchids can be had for just a few bucks.
Take one home, though, and you may quickly find it wizened to a shadow of its former self, or maybe even dead. Before you start blaming yourself for your orchid’s fate and vowing never to try growing one again, consider the problem may simply be that you chose one that’s tougher to grow than others. Orchids are fussy about light, water, temperature and many other things. Knowing which orchids to buy and how to care for them will not only save you from that horrible feeling that you’ve got a brown thumb, it also may make orchid growing so much fun that you wind up cultivating a real passion for the exotic beauties.
More than 25,000 species of orchids have been documented over the world, and botanists believe still more will one day be discovered. The two main types of cultivated orchids are: terrestrial, which live in the rich soil and decaying matter found on the forest floor; and epiphytes, which attach themselves to branches and bark of trees high above the ground so they can enjoy more sunlight. Both are considered tropical orchids, as are most of the orchids we grown in our homes.
Happily, one of the most widely available orchids, Phalaenopsis, or the moth orchid, is also one of the best choices for beginners. Unlike other orchids whose flowers can be short-lived, the moth orchid’s showy, colorful blooms, which some say look like moths, can last for weeks. You don’t need any special lights to keep these plants happy. Just keep them in an east, west or shaded south window. Be sure to keep them out of direct sunlight.
Because moth orchids are epiphytes, they are potted in soil-less mixtures that contain things like bark, charcoal and sphagnum moss. These materials drain easily and offer good aeration. Allow your orchid’s potting mix to get close to dry between waterings, usually every four to seven days. Don’t over water, as I have done in the past, or your orchid will turn into leafless black goo.
As far as temperature goes, experts say orchids do best in the same temperatures we’re most comfortable in. That means nighttime temperatures should be kept to about 60–65 degrees F and days at 70–85 degrees F. (A few degrees either way won’t be a problem.)
Cattleya, often called the corsage orchid because of its ubiquitous appearance on prom night, is another good choice for novice orchid growers. An epiphyte like the moth orchid, Cattleyas also require bright but indirect sunlight. So north-facing windows are generally not a good choice. Watering is a little trickier because Cattleyas’ potting mix needs to dry out completely between waterings (unless you buy a seedling, which will require more consistent moisture). Be sure to keep them out of cold rooms and drafts when they are in bloom.
A little harder to find, but no less stunning, are the paphiopedilums, or Lady’s Slipper orchids. A close relative of North American lady’s slippers known as Cypripediums, these terrestrial orchids are prized for their long-lived blooms, which feature a delicate, slipper-like pouch.
Again, east, west, or shaded south windows provide the best light for these orchids, which need adequate light to grow and flower but will burn if subjected to direct sunlight. Don’t let the potting mix get completely dry between waterings. And because “paphs,” as orchid enthusiasts call them, are sensitive to salt accumulation, it’s best to always allow water to run freely through the potting medium and drain completely before putting the pot in its base.
Now that you’ve got a handle on the light, water, and temperature needed, here are a few more things to know to keep your plants healthy and happy. Orchids grow best in humidity of 40–70 percent. The easiest way to raise humidity around your plants in winter in Minnesota is to group them together on a tray filled with gravel or pebbles and water. Water should be just below the surface of the pebbles so it will not saturate the pots.
Most orchid potting media contain little or no fertilizer, so you will need to fertilize your plants regularly. The type of fertilizer you use depends on your potting material. Orchids potted in bark, for example, need more fertilizer than those growing in soil. Generally, you can use a balanced 10-10-10 fertilizer for terrestrial orchids and a 15-5-5 solution for epiphytes. Fertilize every week when you water with a mixture diluted to a quarter of what the label recommends.
See you in the spring!