Orchids are a bit unique in that they thrive in humidity, yet their roots prefer airflow over soaking wet conditions. Prized for their long-lasting blooms, the many varieties of these tropical beauties rarely require pruning, except to encourage a second bloom or to remove dead or dying leaves or stems.
Pruning Phalaenopsis for a Second Bloom
The Phalaenopsis, also known as moth orchid, is one of the most common varieties since it's the only variety that blooms more than once from the same flower spike or stem. Potted orchids sold in grocery and big-box stores are usually moth orchids.
After the first bloom has faded or dropped off entirely, cut the flower spike at an angle, snipping just above the node or tan spot previously occupied by the flower. This encourages the plant to create new growth at the node, leading to more flowers in two to three months.
Use clean, sharp garden shears, a knife or even a razor blade to cut the flower spike. Whichever tool you prefer, sanitize the blade first with an alcohol-based hand sanitizer or a drugstore variety rubbing alcohol.
The moth orchid may flower again even if you don't prune the spike after the first bloom, but chances are the flowers will get smaller and the stem weaker.
- Note: Orchids are quite delicate and shouldn't be manhandled when it comes to pruning. Even its leaves are tender and may die if accidentally damaged.
After the Second Bloom
A moth orchid requires another pruning once the second flush of flowers fades. Trim the spike down to an inch or so above its base to help the plant refocus its energy on its roots and leaf production. If the plant shows signs of other buds or even nodes on the flower spike, trim to just above these instead. The plant may rebloom after a dormancy period, which could last as long as nine months.
At any point during the moth orchid's life, a flower spike might look withered, brown or yellow or even limp, no longer standing up well on its own. If this is the case, cut it down to 1 inch above its base.
Pruning Other Orchid Varieties
Since other types of orchids don't bloom off the same flower spike, prune them down to just above the base of the flower spike after blooms drop off, in most cases. If the spike has leaves on it, cut to just above the leaves so the leaves stay on the plant. Some orchid varieties such as Dendrobiums and Cattleyas have pseudobulbs that grow on the stalk; if you see a bulge or bump on the stalk, it's most likely a pseudobulb. Cut this type of orchid stalk to just above the pseudobulb. Never cut a pseudobulb off an orchid, as this is where the orchid stores vital nutrients that help it survive.
For a double-spike orchid, cut one spike all the way down to its base after blooming. Trim the other to just above the node beneath the lowest flower bloom.
Don't Prune Visible Roots
Since orchid roots require at least a little airflow, some roots are often visible atop the planting medium. These may appear curved and a bit gray. Even if you feel these detract from the look of the plant, never lop these off, as they're vital to the plant's health.
Pruning a Garden Orchid
One orchid variety in particular thrives well when planted in a garden in areas that aren't likely to freeze in winter. The Chinese garden orchid, also known as Bletilla striata and hardy orchid, is an excellent garden plant in areas receiving partial shade in regions warmer than USDA Hardiness Zone 5. This orchid provides purplish blooms in early spring and lush green leaves in summer. Cut back flower stems after the blooms fade, trimming to above budding leaves. If the orchid shows signs of wilting or dead stems, prune those away in early fall. Cut off any leaves that appear black, as well, sanitizing the shears again before cutting any other plants.
Pruning Roots and Repotting
Like many houseplants, an orchid can outgrow its pot. Unlike some plants, an orchid likes to be root bound, with an abundance of roots filling up most of the pot. Don't repot an orchid just because it's rootbound. Wait until the plant grows too large for the pot, with lots of visible growth—including roots—spilling over its sides. This may take a couple years, depending upon the plant and its original pot. An orchid's roots may also need an inspection if the original growing medium has broken down and needs to be replaced.
Carefully inspect the orchid roots after pulling the plant out of its container. Snip away any wilted, dead or spongy roots, using sanitized shears. Place the plant back in a pot, enlisting a friend's help to hold it up as you add in a bark mix or plant medium specifically made for orchids. Regular potting soil won't do, as an orchid requires a more porous mixture. Add enough potting medium to cover or reach the tops of the uppermost roots. If the plant isn't stable on its own after adding potting medium, add metal orchid clips that span the top of the pot, traveling between stems or stalks on the orchid. These help the orchid stay upright.