December: winter beauty and spring plans

Winter has arrived, but in some central and southern zones, December can sometimes mean surprisingly mild weather, which is good news for gardeners who still have a yen for the outdoors.

There aren't many outdoor gardening chores in this month, so it can be a time of planning for next year's projects.

However, if there are any gardening chores left undone from November—or even October—do them in December, making use of any mild days that come along.

As the weather changes, watch for snow and ice damage on trees and shrubs. Don't allow broken or damaged limbs to remain, and make sure to seal wounds.

In the meantime, if you haven't done so already, consider setting up an indoor greenhouse. Or use the basic design of the greenhouse to create an indoor “garden center,” where you can put ailing houseplants or flowering plants, such as geraniums and African violets, to help them to bloom.

Take some time to care for houseplants in December. Wipe dust from their leaves, repot them if needed and put them in sunny windows. This is especially important for any outdoor pots plants you brought indoors to over-winter. Also, remember to watch for signs of bugs and disease on all indoor plants.

Bulbs planted in containers in September and October for forcing indoors should be blooming. Paperwhites, especially, are gorgeous for the holidays. Keep an eye on other container bulbs, which may still be developing.

Additional bulbs can be planted indoors from December until February, but remember that some, like tulips, need extended periods of cold and darkness before they will bloom successfully indoors.

It's not too soon to sit down in a cozy chair and make plans for next year's garden. Some ideas from last summer may still be fresh in your mind, and December's the time to put them down on paper. In January, you will be creating a 12-month gardening calendar, creating a long-range gardening plan and thinking about a yearly gardening budget.

INDOORS

Indoor greenhouse

• If you haven't done so yet, consider constructing an indoor greenhouse in December to use in starting seeds, perking up houseplants and forcing blooms indoors. It's easy, inexpensive, doesn't take much space and will last for years.

• To add some indoor color on drab December days, start some seeds of annual bedding plants indoors and then transplant them to pots. Let them grow in a sunny window, under adequate artificial light or in the indoor greenhouse. They can provide a gardening “fix” during the gray winter days. Try petunias, coleus, pansies and others that grow fairly quickly and easily and produce blooms or colorful foliage.  Remember that once potted, these plants will require good light and warmth.

• Plant herbs for kitchen use, or just to look at! Herbs can be very decorative indoors. Put the seeds in pots or start them in seed trays and transplant to larger containers. Try chives, dill, fennel, rosemary, tarragon, mint, parsley, oregano, cilantro (coriander) and dwarf basil. Put some fresh spices into your December cooking.

• Most seeds that will be transplanted outdoors shouldn't be started indoors until mid- to late February, at the earliest. However, you can begin gathering the materials you will need for Starting Seeds.

Mail Ordering

• Start looking at bulb, seed and nursery stock catalogues and their online sites in December to see what they're offering for the upcoming spring season. Many times, if you don't order early enough, they run out of the most popular seeds (such as a crimson coneflower that I desperately wanted a few years back.).

• If you decide to order seeds, think about when to start them inside, either with an indoor greenhouse or in another setting that will provide adequate light, warmth and water during the growing period.

Forcing bulbs in December

• If you planted container bulbs in September and October, now is the time to bring them into light and warmth. Check to make sure they have been dormant long enough. (See Forcing Bulbs on the Home Page for details.)

• Container bulbs should have been resting in a cool, dark place since being planted. If they have been in these conditions long enough - according to the type of bulb - then move them in December to a sunny window or under a consistent artificial light source. Water sparingly until blooms appear. No need to feed, unless you want to transplant the bulbs later outdoors. After blooms have opened, they will last longer if they are removed from direct or strong light and kept in a fairly cool place. But turn the containers frequently so the plants won't lean toward the light source.

• You can still plant paperwhites or daffodils in pots or dishes of gravel indoors for March bloom. Others spring flowering bulbs, such as hyacinth, can also be forced indoors. (See Forcing Bulbs on the Home Page).

Tips for Poinsettias in December

• Your new holiday poinsettia will last into January if cared for properly. Place it in a warm, sunny window and keep it out of drafts. Sudden chills will cause the poinsettia to drop its leaves. If the soil surface is dry, water, but don't allow the poinsettia to stand in water. Don't water again until the soil becomes dry. If you find mealy bugs, pick them off with a toothpick dipped in alcohol.

• In late winter or early spring, when the leaves begin to fall off, place the poinsettia in partial darkness and about once a week give it just enough water to prevent complete dryness. Leave this way until May.

• If you have set out a blooming poinsettia that you kept from last year, you must still keep moving it into a dark closet each night (see poinsettia notes in November and October) for at least 14 hours per night, and then back into sunlight each day. Continue this until about mid-December, when it should begin showing colored leaves and you may leave it in normal household conditions.

OUTDOORS

Annuals

• Cool-tolerant annuals, such as ornamental kale, chrysanthemums and pansies may be watered and fed if they are still growing and producing new leaves and blooms. However, most of these are nearing the end of their season, except in the southern-most zones. If these plants start looking scraggly, cut them back or remove them.

• If matted leaves and debris have obscured plants such as ornamental kale, pansies and holly bushes, gently rake them away from the plants. But try not to disturb the protective mulch layer on the soil. This helps retain moisture and soil temperature, and prevents “heaving.”

Bulbs

• December is a good time to examine the stored roots, corms and bulbs of dahlias, cannas, gladiolus, tuberoses, caladiums, tuberous begonias and others that you dug up in the fall. These should remain plump and firm, and should not show signs of growth or rotting.  Throw out rotting ones, and if others are showing sprouts and roots, place them in a cooler, darker place and make sure their packing material is dry. The back of the refrigerator is cold enough to stop such growth.

Perennials

• Watch for “heaving” of perennials, including chrysanthemums and hardy ferns. Bulbs sometimes get pushed out of the ground, also. The freezing and thawing of the soil causes heaving. Gently push any exposed roots or bulbs back into the soil and cover with mulch.

• If you didn't apply cold weather protection to roses, do it in December. There are several ways to provide protection. One is to pile a light peat mixture over and around the plants, and mulch high around the stalks. Consult a rose expert or gardening book for more ideas on protecting roses during the winter.

Pests and diseases

• If there is heavy snow, check fruit and flowering trees for rabbit damage. If you find any, wrap the trunks with protective tape.

• Watch for signs of pests and diseases on houseplants. Aphids, red spider mites and others can appear seemingly over night. Apply appropriate controls.

Pruning

• American holly bushes respond favorably to pruning this month. Most other plants should be pruned in the spring, summer or fall.

• Prune outdoor limbs or branches that have been damaged by winter storms. The damaged parts should be removed immediately, and the pruning wounds should be sealed with paint or some other substance that will protect it from invasion by pests and diseases.

Tools and equipment

• If you didn't do it in previous months, or you have used some tools since putting them away for the season, take a day in December and clean, oil and store garden tools and equipment, such as shovels, sprayers, wheel barrows, etc.

• The same goes for hoses. Even if you plan to use the hose this month, store it indoors. If you don't plan to use it any more, drain it, wind it up and bring it indoors. Sprinklers should also be stored indoors.

• Think about the snow blower or thrower before you need it. Does it need a tune-up? Is it in good working order? How about the snow shovel? Is the handle broken? Would a new one be easier on your back? Think about it before the first six-inch snowfall finds all your neighbors rushing to the hardware store for the same reason.

Trees and shrubs

• Shrubs, evergreens and trees may still be transplanted, weather permitting. Some experts say the best time to transplant any new trees and shrubs is during their dormant season.

Snow removal

• Be careful using salt or ice melt in areas near lawns or flower beds, since this can damage perennials and grass, and ruin the soil for spring planting. Keep off the grass as much as possible during the winter months. If needed, you can still rake areas of matted leaves. 

Watering

• If the month is unusually dry (no rain or snow for 14 days or more), get out the hose, turn the water back on during a (relatively) warm weekend, and give newly transplanted trees and shrubs a drink. REMEMBER: When you are finished, shut off the water supply to outdoor spigots, or you could have burst pipes later.

Birds

• If you haven't set out a bird feeder, do it this month. They'll thank you by coming for daily visits and singing for their supper. Once you have drawn birds to the feeder, keep it filled. The birds will depend on you.  Make sure to keep the food out of the reach of squirrels, which  will do their best to steal any bird food they can.

• During dry and frozen times, fill the birdbath. Haul out the hose or simply fill a pitcher with water. This gives the birds something to drink. Some gardeners invest in birdbath warmers to keep the water from freezing.

Miscellaneous

• For indoor decorations, clip off a few shapely, bare branches from a bush or tree and bring them indoors for an arrangement. To the branches, add dried flowers, strings of beads, paper snowflakes, ornaments or whatever sparks your imagination. Arrange them in tall vases for a dramatic effect.

  

• Another idea for winter decoration is to carefully clip off some small evergreen branches to use indoors for a wreath, a table arrangement or other decoration for the season. Small holly branches can also be snipped off for indoor arrangements and seasonal decorations. 

• Wood ashes from the fireplace are a good source of nutrients for the garden, especially delphiniums, phlox, sweet William, peony and spring-flowering bulbs. They also help lilacs, lawns and annual flowers. To use wood ashes later on spring plantings, store them in December in an old metal tub or other dry and fire-proof container.  CAUTION: Make sure there are no live coals before storing wood ashes. Set them outdoors or in the garage or basement.

• A word of advice: resist the urge to feed squirrels in the winter – unless you want them to stay around all spring and summer, establish their families in your yard. Squirrels are cute to watch but they can be very damaging in a garden. After you stop feeding them, they'll still stay and will keep looking for food, digging up bedding plants and even potted plants, looking for roots to chew on or bulbs to eat. Plus, squirrels like to sharpen their teeth on things such as garden statuary.