Jessica Damiano Jessica Damiano, Newsday columnist

Jessica Damiano is a master gardener and journalist with more than 25 years experience in radio, television, print

You’ve decked the halls and spent good money on festive plants, but now the festivities are over. The tree is down and ornaments packed away, but your living herbaceous décor still needs your attention.

With proper care, you can extend the life and blooms of poinsettia and Christmas cactus — and even get to enjoy them again next winter. Here’s how.

POINSETTIA

Provide water and sunlight for poinsettias until they stop blooming. When the flowers (technically, they’re bracts, but we’ll call them flowers) are gone, allow the plants to dry out.

When potted plants have entered dormancy, lay them 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, they’ll need a little spritz of water. This may not be necessary.

The new Ice Punch Poinsettia at Home Dep has rich, rosy red bracts with naturally marbled cream centers. Available in 6- to 8-inch pots for $8.97 - $18.99). For Home Section/ Jessica Damiano's Garden Detective page

In April, bring 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.

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You can move poinsettias outdoors around Memorial Day or continue to keep them as houseplants over the summer. Either way, fertilize once a month with one teaspoon per gallon of a complete fertilizer (20-20-20).

Around Labor Day, check for insects, and, if you find any, pick them off by hand or rinse the plants with a gentle stream of water to remove them, then bring plants indoors. (If they’re already indoors, just keep doing what you’ve been doing.) Place by a sunny window and continue to water and fertilize monthly. Poinsettias do best if temperatures are kept between 70-75 degrees during the day and 60-65 degrees at night.

To form flower buds, poinsettias require a period during which they are deprived of light for about 15 hours daily. So for 40 days beginning 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.

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.

CHRISTMAS CACTUS

Growing a Christmas cactus (Schlumbergera bridgesii) can seem a bit tricky. But if you treat the plant right all year long, the exotic bloomer will reward you with a profusion of orchid-type flowers during the holidays.

From September through December, keep the plant in a 50- to 65-degree environment, water only minimally and mist twice a week. To force blooms successfully, plants should be kept in complete darkness from 5 p.m. to 8 a.m. daily for eight to 10 weeks before Christmas.

By next December, when buds form, move the plant to a sunny location in the main part of the house where you’ll be able to appreciate its flowers, and resume regular watering. 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, repot plants into the next size container in a mix composed of equal parts houseplant potting mix, coarse sand and perlite.

From April through June, keep the plant indoors in indirect sunlight and water frequently. Include African violet fertilizer at half strength with every second watering.

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During July and August, keep the plant outdoors in a bright, sunny location and allow the soil to remain fairly dry to promote the development of buds.