Garden Detective

How to get an orchid to rebloom

I have had an orchid for about seven years that used to bloom quite often. I accidentally dropped it a few years ago and broke off the stem that contained the flower, and it hasn’t bloomed since. Is there anything I can do to get it to produce a flower again? Other than that, the plant is healthy, a dark green with firm leaves. I have about four orchids, two that bloom and two (including the aforementioned) that don’t.

Merle Heard, Sacramento

We’re going to assume that your orchid in question is a Phalaenopsis, one of the most common orchids available. These orchids often produce new flowers from old stems.

Phalaenopsis or moth orchids tend to thrive on what seems neglect: Water every three weeks and fertilize every other month. Use a balanced fertilizer (such as 8-8-8) with equal amounts of nitrogen, phosphate and potassium, the macro-nutrients that all plants need for development. In the wild, orchids depend on decomposing leaves for most of their nutrients, so they don’t need much.

For best results, use a water-soluble fertilizer specifically designed for orchids. According to experts, orchids planted in bark may need a higher amount of nitrogen (the first number in that three-digit formula) because the decaying bark will use up a lot of the available nitrogen, leaving little for the plant. That’s why some orchid foods are 30-10-10, for example.

Before feeding, water the plant well and get its bark, moss or other planting medium moist but not soggy. Discard any water and/or fertilizer that accumulates.

To get a moth orchid to rebloom, trim the flower spike (but not all the way) and let the plant settle into its new bloom/growth cycle. Moth orchids like a tight-fitting pot. Roots that extend through the air above the pot edges are natural; the plant is seeking moisture and room. Look for nice, green root tips on plump, white roots as a sign of a growth spurt, then choose a slightly bigger pot. Repotting with moss is recommended after blooming, usually every other year in late spring or early summer.

Phalaenopsis are among the few orchids that will rebloom in home conditions. The spike should be cut between the scar that’s left by the first flower and the last node (that little lump) on the stem. One of the lower nodes will then initiate and produce flowers within eight to 12 weeks.

If no bloom cycle starts within two months or if the stem yellows, cut the stem all the way off and allow the plant to go dormant. Water and fertilize every three to four weeks and wait.

Or try this trick: Drop the temperature at night.

Moth orchids are temperature-sensitive. Four to six weeks of cooler temperatures – 55 to 60 degrees – triggers flowering. Professional growers cool their plants for 30 to 40 days at 60 degrees to prompt new flower cycles. This can be accomplished by placing the plant close to a north-facing window in winter or in an enclosed porch. Remember: The orchid still needs indirect light.