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Ask the Gardener: How to care for Christmas trees and plants

Ask the Expert
Christmas-Tree-Lot
Christmas trees can drink a gallon of water a day. Debee Tlumacki for The Boston Globe/File 2014

Evergreens and fresh flowers can make great holiday gifts and decorations. Before shopping for material, check your garden for useful evergreen and winterberry branches, plus pine cones and seed pods for spray painting. Just a bit can personalize the wrappings and decorations you buy, the way basil and parsley from your herb garden brightened summer meals.

But know your enemies! Many a tree has been strangled by a single berry dropped from a cheerful-looking wreath of treacherous bittersweet. Shun these orange and red capsules and also turquoise porcelain berries the way you would avoid adding pretty dandelion puffball seedheads to backyard bouquets.

Trees

Live Christmas trees are the royalty of holiday plants. Buying and decorating natural trees can create family memories. The difference between a real tree and an artificial one is the difference between a homecooked meal and takeout. If you want to cut your own, visit the Massachusetts Christmas Tree Association (christmas-trees.org) to find the nearest farm.

(Which Christmas trees smell best, last the longest? How to choose one.)

Treat a Christmas tree like a bouquet of cut flowers that you want to last. If you buy it from a lot, tap the trunk butt on the ground to make sure it’s not shedding needles. Get your tree on a warmish day so it won’t be shocked by the temperature change when it moves indoors. Have the seller cut a couple of fresh inches off the end of the stump to reopen the tree’s dried-out xylem (circulatory) vessels so it can drink. Put it in a deep bucket of water the minute you get it home, or recut the stump just before setting it up in a stand with the largest water reservoir you can find.

Trees drink a lot of water every day, so the stand needs to be topped off every night when you turn off the lights. If it goes empty and the cut end dries out, the tree will no longer be able to suck up water and will dry out, even if you belatedly refill the reservoir. A humidifier will benefit your tree, plus any houseplants in the room. A pan of mulled cider simmering on the stove also will contribute.

Real trees have uses after the holidays. After removing the decorations, I recycle mine by cutting up and laying the tree’s boughs in my perennial garden to help protect it against sharp fluctuations between warm and cold days, which can cause root-breaking frost heaves. These temperature whipsaws are becoming more common with climate change. When the needles drop, you can leave them in place as permanent mulch, removing the skeletal limbs in the spring. I also sometimes place the entire tree near a feeder to provide cover from hawks for birds waiting their turn. Don’t burn it in the fireplace. I caused a chimney fire one year from creosote buildup by doing that.

Plants

The most popular flowering Christmas plant is the good old poinsettia, which will continue to bloom all winter with a little watering and even less light. Eventually you should throw it out, because the plants are cheap and almost never rebloom. The “flowers’’ are actually bracts, or modified leaves, which is why they stay colorful for so long. (The same goes for dogwoods and hellebores.)

Amaryllis bulbs also are in demand now. You can buy them as kits to give or grow. But they seldom bloom in time for the holidays, so many people are now buying them in bud or bloom. Paperwhite narcissus bulbs are popular for their sweet fragrance. To sprout your own, set them on top of a bowl of pebbles in water that just touches the bottom of the bulbs, which will anchor themselves by sprouting roots. Discard after blooming.

Fuchsia and white phalaenopsis orchids have become less expensive and more popular in recent years due to mass production and air freight. Like Christmas cactus, they are easy, long-lasting, and can rebloom if you water them weekly and fertilize them monthly after blooming. Move them from a location with four hours of indirect light to a shady spot outside each summer until the cold weather returns. When they rebloom is determined by the variety.

When bringing tropical plants (or cut flowers) home from the store or to someone’s house as a Christmas gift, wrap the entire plant, including the pot, in newspaper that has been taped shut to keep out the cold. Even a few minutes of frigid weather can kill some plants.

Note to readers: I will be taking my winter hiatus soon, so please do not send your garden questions until next spring.

Enjoy the holidays!

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