Dear Jessica: My Christmas cactuses are almost in full bloom. Both plants are about 40 years old and are in need of repotting and new soil. Any help on how to and when to do this would be greatly appreciated.
— Walter Paluch
Dear Walter: First of all — congratulations! Keeping a houseplant, especially a finicky one like Christmas cactus (Schlumbergera bridgesii), thriving for 40 years is deserving of some serious green-thumb respect.
You obviously already know this, but to illustrate for other readers — and provide instruction for those attending their first rodeo this year, the plants can be a bit tricky.
General care guidelines require that from September through December, the plant is kept in a 50- to 65-degree environment, receiving only minimal water and misting twice a week.
To force blooms for the holidays, plants need to be kept in complete darkness from 5 p.m. to 8 a.m. daily for eight to 10 weeks before desired bloom time, which typically falls on Christmas.
When buds form, the plant should be moved to a sunny location in the main part of the house and regular watering should be resumed. Do not move the plant — even slightly — after this time. Seriously, don’t even rotate the pot. Blossoms will drop at the slightest provocation.
In March, on alternate years, plants should be repotted into the next size container, planted in a mix composed of equal parts houseplant potting mix, coarse sand and perlite.
From April through June, keep plants indoors in indirect sunlight and water frequently. Include African violet fertilizer at half strength with every second watering.
During July and August, move the plant outdoors to a bright, sunny location and allow the soil to remain fairly dry to promote the development of buds.
Rinse and repeat.
While we’re on the subject of holiday plant care, let’s talk a bit about poinsettias.
Many folks ditch these holiday staples after their “flowers” fade (they’re actually not flowers but rather colorful modified leaves called bracts — but let’s call them flowers here because everyone else does). Nevertheless, poinsettias can be kept for years with proper care. Again, however, holiday rewards don’t come easily.
If you have these beauties in your home right now, provide water and sunlight until they stop blooming. When the flowers fade, allow the plants to dry out.
When they have entered dormancy, lay plants on their sides in a cool, dark place, such as an unheated cellar, until April. Check on them periodically; if the woody stems start to shrivel, mist them with water though this may not be necessary.
In April, move the plants back into the main part of the house, trim about 2 inches from the end of each stem, place by a sunny window and water regularly, keeping soil moist but never soggy.
Around Memorial Day, you can move them outdoors — or continue to keep them as houseplants over the summer. Either way, fertilize once a month with one teaspoon per gallon of a complete (20-20-20) fertilizer product.
Around Labor Day, check for insects, picking any off by hand or rinsing the plants with a gentle stream of water to remove them, and bring plants indoors. If they’re already indoors, continue to provide the same care. Place by a sunny window, and water, and fertilize monthly. Poinsettias do best if temperatures are kept between 70 and 75 degrees during the day and 60 to 65 degrees at night.
To form buds, poinsettias require a period during which they are deprived of light for about 15 hours each day. So for 40 days beginning on Oct. 1, keep them in a very bright, sunny spot from 8 a.m. to 5 p.m. every day, then move them into complete darkness from 5 p.m. to 8 a.m. (A closet is perfect for this.) Do not skip this, even for one night, or buds may not form. This is not for the lazy, or faint of heart. But again, keep your eye on the reward.
By Nov. 10, you should notice bracts taking on a reddish hue. From this point on, keep plants in the main part of the house around the clock and continue to water and fertilize. You should be seeing red (or white) in time for the holidays, and can bask in the glory of self-satisfaction, plus save a few bucks on new plants.
Dear Jessica: I received a calla lily as a gift in the spring. I planted it in a clay pot with other flowers. I’m wondering if rather than digging it up, I can move the pot into my garage to protect it from a possible harsh winter and hope it will re-bloom next year, and if so what care do I need to give it?
— T. Wallace
Dear T: Yes, calla lilies certainly can be overwintered indoors if growing in a pot.
When the last blooms fade, bring the potted plant indoors. Stop watering, but apply a potassium-rich fertilizer just once.
After the leaves die back, move the plant into a dark, cool (but not freezing) spot in the house, like a basement or attached garage.
Move the plant back into a sunny part of the house in early spring, and resume watering. You can set it back outdoors after the danger of frost has passed, but acclimate it gradually by leaving it outdoors for increasing periods over the course of several days.