Orchid care for beginners: how to keep a moth orchid blooming

The orchid most of us bring home is a moth orchid, or Phalaenopsis. It is the one sold at grocery stores and garden centers, with arching sprays of flat, round flowers. It is also the easiest orchid to grow in a house.

Moth orchid care comes down to three things. Give it bright light without hot midday sun. Water it well, then let the bark almost dry. Give it a few weeks of cooler nights in fall so it grows a new flower spike.

Light

In the wild, moth orchids grow on tree trunks under a canopy of leaves. They like bright, filtered light. An east-facing window is ideal. A south or west window works if a sheer curtain softens the afternoon sun.

The leaves tell you if the light is right:

• Medium olive-green leaves mean the light is good.
• Dark green, floppy leaves mean the plant needs more light.
• Yellow-green leaves, or leaves with a red tinge, mean too much light.
• White or brown patches can be sunburn.

In winter, a grow light helps if your windows are dark. A small pendant grow light works well over a shelf.

Watering

Overwatering is the most common way people kill moth orchids. The roots need air. In soggy bark, they rot.

Water when the bark is almost dry. In most homes, that is about once a week. It can stretch to 10 days in winter. Look at the roots through the clear pot. Silvery roots are dry and ready for water. Green roots are still wet.

To water your orchid:

1. Take it to the sink.
2. Run room-temperature water through the bark for 15 to 30 seconds.
3. Let it drain all the way.
4. Dab any water out of the crown, where the leaves meet. Water left there can cause crown rot.
5. Set it back in its decorative pot. Do not let it sit in water.

You may have seen the tip to water with three ice cubes a week. A full soak at the sink wets every root and flushes out fertilizer salts. Ice cubes do neither.

Humidity and temperature

Moth orchids like humidity of 50 percent or more. Most homes in winter sit well below that. Set the pot on a tray of pebbles with water below the top of the stones. Grouping plants together or running a humidifier also helps.

They like the same temperatures you do. Aim for 70 to 85°F (21 to 29°C) during the day and above 60°F (16°C) at night. Keep them away from heat vents, cold windows, and doors that open to winter air.

Feeding

Use a balanced orchid fertilizer at one-quarter strength each time you water. Once a month, water with plain water to flush out salt buildup. Small, frequent doses are safer for orchid roots than a full-strength feeding.

How to get a moth orchid to bloom again

Moth orchid flowers can last two to three months. After the last flower falls, you have two choices for the old spike.

• Cut it above a node. Find the second node (a small bump with a brown sheath) below where the lowest flower grew. Cut about 1 inch (2.5 cm) above it. A side spike may grow from that node and bloom in a few months.
• Cut it at the base. This lets the plant put its energy into new roots and leaves. It should bloom again the next season.

If the old spike turns brown or yellow, cut it at the base. It will not bloom again.

To trigger a new spike, give the plant cooler nights in fall. A drop to about 55 to 60°F (13 to 16°C) at night for a few weeks does it. A spot near a cool window in September or October works. Keep daytime temperatures in the normal range.

A new spike has a flat, mitten-shaped tip. A new root has a round, green tip. Most moth orchids bloom once a year.

Repotting

Repot every one to two years, right after the plant finishes blooming. Orchid bark breaks down over time. Old, mushy bark holds too much water and rots roots.

1. Slide the orchid out of its pot.
2. Tease the old bark away from the roots.
3. Trim off brown, mushy, or hollow roots with clean scissors. Firm green or silver roots are healthy.
4. Set the plant in a clear plastic orchid pot one size up. Use the same size if you trimmed off a lot of roots.
5. Fill around the roots with fresh orchid bark. Tap the pot to settle it.
6. Wait a few days to water, so the cut roots can seal.

Roots that grow up and out of the pot are aerial roots. They are normal. Leave them alone.

Common problems

Problem	Likely cause	Fix
Bottom leaf turns yellow and falls	Normal aging	Nothing, if new leaves are growing
Several leaves turn yellow	Overwatering or root rot	Check the roots and repot in fresh bark
Limp, wrinkled leaves	Roots cannot take up water	Check for rot, then adjust watering
Buds dry up and fall off	Drafts, heat, moving the plant, or ripe fruit nearby	Keep it in one stable spot
No new flower spike	Low light or no cool nights	Move it to brighter light and give it cool fall nights
White cottony spots	Mealybugs	Dab them with a cotton swab dipped in rubbing alcohol

Ripening fruit gives off ethylene gas, which can make buds drop. Keep orchids away from the fruit bowl.

Fine speckles on the leaves and thin webbing underneath point to spider mites. Here is how to get rid of spider mites.

Are orchids safe for pets?

The ASPCA lists the moth orchid (Phalaenopsis) as non-toxic to cats and dogs. That makes it a good pick for a home with pets. Bark and fertilizer can still upset a pet’s stomach if eaten.

More flowering houseplants

If you enjoy your orchid, try another easy bloomer next:

• Anthurium
• Christmas cactus
• African violets