Monthly Gardening Calendar
Sharon Morrisey, Consumer Horticulture Agent
Milwaukee County UW-Extension

December, 2007

Join the “greening” trend this season by “giving green” for the holidays. In the literal sense, there are those beautiful floral traditions of the season with potted poinsettias, amaryllis, Christmas cacti, Jerusalem cherries, azaleas, kalanchoes and more. In the trendier context, green giving means gift certificates and gift memberships to environmentally correct causes. Locally, there are the county horticultural facilities such as Boerner Botanical Gardens, Wehr Nature Center and the Domes. The Retzer Nature Center in Waukesha, Schlitz Audubon Center, the Urban Ecology Center, Riveredge, and Havenwoods State Forest all have Friends groups helping to fund support of their missions. Thinking nationally and globally provides a multitude of opportunities to support programs that are making a difference on environmental issues all over the world.

In your own backyard, wish for a white winter. Whether you like snow or not, our garden plants generally do. What we hope for is a gradual cool down until the soil freezes and plants become dormant. Then we want a blanket of several inches of snow that sticks around until spring thaw. Our plants’ worst winter nightmare is of a warm November suddenly plummeting to temperatures in the single digits with no snow cover and fluctuating temperatures all winter long.

If you find the time this holiday season, there still are a few tasks to take on in the yard. Indoors use fresh and live holiday decorations liberally. Be sure to recycle trees and wreaths when it is all over. They can be chipped for mulch or used either whole for bird feeding stations or with branches stripped and used to blanket tender perennials and new transplants.

Garden calendar entries followed by a number in parenthesis, have corresponding UW-Extension InfoSource messages that will provide further details on that subject. View or download and print these messages from the website http://infosource.uwex.edu .

The UW-Extension Publications on many of these topics are available on-line at: http://learningstore.uwex.edu. Or contact your county UW-Extension office.

 

First Week

To dress up empty planters, branches may be pruned sparingly from evergreens and deciduous shrubs with colorful or interesting bark. As a general rule, major pruning is best done at the end of the dormant season in late February and March.


Needle-type evergreen boughs may be used to shield broadleaf evergreens like rhododendrons and boxwoods from sun and wind. Stick the stem ends into the ground to surround and protect small plants with a naturalistic look. Or use burlap and stakes to loosely surround but not completely cover them or create a screen especially on the windward side.

Evergreens growing close to roads where fast moving traffic produces a salty spray over the winter should also be protected.

Remove tall grass and weeds from the bases of trees, too. Protect trunks of young trees by wrapping. Spiral plastic trunk barriers or hardware cloth close to the trunk are the best options. Surround multi-stemmed and low branching trees and shrubs with chicken wire or hardware cloth held securely against the ground. It should be tall enough to protect branches as high up as a rabbit can reach when on its hind legs on top of a snow bank.


Combine several tactics to scare away animals that can damage your plants in the winter. Shiny, noisy, moving objects hung in the garden along with bags of human hair or soap can be used in addition to commercial repellents or ones prepared at home. Remember to reapply these substances often since most of them lose their potency quickly.

Check your yard, garage or tool shed for garden products and equipment that should be stored indoors for the winter. Liquids should not be allowed to freeze. Pesticides should be stored locked, out of the reach of children, and in their original containers. Plastic sprayers and rubber and vinyl hoses should be stored empty, preferably indoors.


Winterize your lawn mower by running the engine dry, draining and replacing the oil, cleaning the air filter, oiling the plug, and wiping clean the engine. Now is a great time to take it in for a tune-up and blade sharpening so it’s ready as soon as that first surge of growth comes in the spring.

Clean garden tools with a wire brush and apply a light coat of oil to protect them from rusting. Sharpen edges of hoes and spades. Clean, readjust and sharpen the blades of pruning tools. Lightly sand handles and then apply a coat of linseed oil.

 

Second Week

If the ground is finally frozen an inch or so deep, it is now safe to apply winter mulches to newly transplanted or tender perennial flowers, roses and strawberries. This will insulate them from the cold above ground and help reduce the fluctuations of temperatures in the soil throughout the season, which can heave their root balls right out of the ground.  

Surround rose bushes with chicken wire cages and fill with up to two feet of chopped, dry leaves or straw to protect them for the winter. Cover the base of the stems with several inches of soil or compost first and then place the chicken wire on top of the mound after it has frozen. Tie canes together with cloth strips or nylons to keep them from rubbing when they are blown by the wind. Do not cut them at this time. Wait until next spring when you will know how much was killed and therefore how much to prune out.


Mulch strawberries with straw, leaves, or evergreen boughs. Mulch needs to be 6 inches deep after it has packed down. Branches cut from a discarded Christmas tree are perfect either as the mulch or to prevent straw or leaves from blowing away.


Pile soil or compost over the crowns of garden chrysanthemums that are in very exposed sites for the winter. Then add inches of mulch on top. Whether covering mums or not, do not cut off dead stems until next spring.


A thick layer of straw over root crops like potatoes, parsnips, and carrots as well as parsley and leeks will protect them long enough to harvest them a little at a time well into the winter.

 

Third Week

Cyclamen, Christmas cactus and azaleas are good choices for people who keep their houses cool. Also look for Jerusalem cherry, ornamental peppers, and kalanchoes. Be sure to cover them when transporting even a short distance - most are very sensitive to temperatures below 50 - 55 degrees.


Floral arrangements should be kept cool and out of the sun. Contrary to common belief, arrangements and cut flowers should be watered with very warm water which contains floral preservative. Re-cut flower stem ends first and then condition them in a very cool spot for several hours before bringing them into warmer rooms. Every couple of days, re-cut the stem ends, wash the vase with soap, and refill with warm floral preservative water. Substitute non-diet lemon lime soda or vinegar and a drop of bleach if you don’t have preservative on hand (not an aspirin, a penny or a nail as is sometimes recommended. These don’t work.)

Check stored vegetables like tomatoes, potatoes, onions and garlic and non-hardy bulbs like canna, tuberous begonia, dahlia, and gladiolus for mildew and rot. Remove affected items immediately.

Geraniums stored dry in the basement or attic for the winter should be checked and the root systems moistened. Do this monthly all winter.

Avoid rock salt, which is sodium chloride, to melt sidewalk and driveway ice. Products made of calcium chloride or potassium chloride cause less damage to plants. For traction, sprinkle sand, kitty litter, or wood ashes sparingly. Mix with a little melting compound if more than just traction is needed. Minimize de-icing and traction products to reduce pollution in storm sewers and streams.

 

Fourth Week

Watch your new holiday gift plants closely. Most of them need bright but indirect light and moderate temperatures. Keep them out of drafts as well as away from the hot air from heat vents, fireplaces, and TV's. Keep the soil just slightly moist and do not allow them to stand in runoff water.

Adjust your indoor plant watering practices as needed according to the weather conditions. Plants use less water on cloudy days and during the short days of mid-winter. December 21st is the shortest day of the year. Cool conditions indoors may also mean less water is needed.


Groom indoor plants to clean leaves, remove fallen leaves and faded flowers. Cleaning removes dust and grease that can clog leaf pores. Hand dust large-leaved plants with a pair of old socks or gloves on both hands. Put a individuals or groups of plants in the shower if hand washing is not possible. To keep soil from washing away cover it with foil, newspaper or plastic.