December Gardening By the Month

“How did it get so late so soon? Its night before its afternoon. December is here before its June. My goodness how the time has flewn. How did it get so late so soon?” -Dr. Seuss


(Poinsettia are here and in some fun colors to choose from. Think they only come in red and white? No way, not at Rainbow Gardens!)

Please note, most of the information shared here was obtained from Research-based sources (see contributors acknowledgements below), and from individuals who are considered very knowledgeable on a particular subject.  While some little tidbits here may be of interest, they should be taken “with-a-grain-of-salt”. (compiled by MG Brian D. Townsend)


background-15425_6401st WEEK:

First week typically for freezes!!!  Keep in mind, when monitoring severe weather conditions, “radiational-cooling” type freezes causes different reactions to plants than a “wind-blown” freeze. If it hasn’t rained in the last 2-3 weeks, water heavily a day or two before freezing cold fronts move in. And, if temperatures below 24 degrees (32 degrees for some cold-tender plants) are forecasted, provide mulch, then water all landscape plants (especially St. Augustine lawns) deeply, 12 to 24 hours before temperatures fall below freezing.

The ritual of taking down the hummingbird feeder is more folklore than science.  Leaving them up, in fact, would benefit both native and migratory hummingbirds, according to a state & local birders.  Keep your feeder about 1/4 full and change about once a week (inspect on cold mornings to make sure it’s not frozen).  A red feeder (avoid using red dye in solution) is enough to attract the birds, although red flowering plants such as the shrimp plant close by will help even more.

Remove, by hand, the mistletoe on mesquites and other shade trees in the landscape if you want to reduce stress on the tree and encourage long life.

Pruning can be done on trees that need it (if temperatures are above seasonal average, wait a couple of weeks), including shade trees, evergreens, summer-flowering shrubs and vines, fruit trees and grapes.

Last call to defoliate young specimens of hybrid Crepe Myrtles to induce dormancy.

It is still a good time to plant shrubs and trees.  If transplanting shrubs, cut the tops back 1/3 to 1/2 to compensate for root lost in digging and replanting.  Plastic-potted shrubs only require some root pruning if roots are circling obsessively, and long branches or overgrowth needs control.

Shrubs that provide winter berries for birds include pyracantha, ligustrum, holly and nandina.

Pansies planted now will provide color all winter (Violas, also called Johnny-jump-ups, are perfect border plants for pansy beds – EO).  They do best in full sun.

Apply SNAIL & SLUG bait or beer traps to protect pansies, bluebonnets, chives, day lilies and other plants for which the creatures have a fondness for.

Refrigerate or freeze pecans to extend their usable life.  Shelled pecans last about 2 months (4 months left in the shell) at room temperature, 12 months refrigerated and 24 months frozen.

Expect the leaves of red oak, bur oak, fruit trees, mulberry, pecan, hackberry, redbud, ornamental pear, cedar elm, sycamore and other species to lose their green color and drop.  Mow your leaves and let them decompose on the lawn or use them for mulch or compose.

Be prepared to cover tomato cages with blankets and plastic when the first freeze is predicted.  You often can get 2 or 3 weeks of good weather if tomatoes make it through the first freeze. If they were damaged by earlier weather, to the mulch pile they go.

String monofilament fish line at shoulder level for deer to create an effective barrier for the plant-eating animals. – CF

Water shrubs and trees if they are suffering from prolonged dry weather.

Use berries from nandina and holly for natural holiday color indoors.

Hold off on cutting back lantana and salvia after the tops freeze. The tops will offer additional protection to the roots in future freezes.

Great Texas Garden Tips – Cut back fall blooming perennials now (bulbs cut back only as leaves brown).  This tidies up the plantings and helps to get them ready for new growth next spring.

Scale insects are a problem with any planting, so as a preventative, now is time to apply dormant or horticultural oil according to the label.  Dormant oil should always be applied after plants reach dormancy and before new spring growth occurs. One spraying in December and another one in January.

If you fertilized your cool/cold season annuals only at planting, it is time to fertilize again according to label directions to help keep them healthy, actively growing, and blooming well.

December is still spring bulb, corm, rhizome, and tuber planting time in Texas to have a show of color from these plant selections next spring. The cold weather makes the soil a great temperature to keep the bulbs cold once planted.

Have the soil tested in your vegetable garden, rose garden, perennial garden, lawn, or any other special area in your landscape this month.  The results of the tests will offer recommendations to help you achieve the most results from your gardening activities. – DGDG


poinsettia-379895_12802nd WEEK:

The best control for weeds in the winter lawn (if you forgot to use pre-emergent herbicide) is to mow every 14 to 21 days.

Don’t let poinsettias dry out.  Water heavily outside or in the sink before wilt, and wait until they look slightly limp again. If heating is used often indoors, watering frequency will need to be increased.

Many of the hibiscus, plumeria, bougainvillea and other tropicals have quit blooming for the year.  They can be moved into freeze-protected storage.

Watch pansies and other cool-weather annuals until they become established.  Sunny, hot weather (and yes, we can still get hot too) will make them wilt.  Water as needed, until they develop a root system.

Fertilize onions, broccoli, cabbage and other cool-weather foliage vegetables with 2 cups of organic fertilizer or 1 cup of slow-release lawn fertilizer per 10 ft. of row.  Use half the amount for carrots, beets, turnips and other root crops. – CF

Don’t prune woody plants, unless they are already dormant.  Wait until February.

If you can find them, continue  to set out pansies, violas, stock, snapdragons, dianthus and flowering kale. – EO

Cut back on fertilizer for indoor plants in winter.

Keep holiday gift plants moist and ensure good drainage to prolong their life.

christmas-cactus-71455_6403rd WEEK:

Never water frozen leaves.  Watering will kill, not thaw them.

Pick broccoli, radishes and other winter vegetables when young for highest quality and best production.

Keep your Christmas tree well-watered, out of the sun and away from heat registers, this will help them from drying out making them smell fresh and avoiding a fire hazard.

Don’t worry about being a “neatnik” in your lawn.  Mow leaves and let them decompose on the lawn and flowering shrub beds.  Birds, squirrels and deer will clean up acorns and pecans.

On warm, sunny winter days, water St. Augustine grass (in the morning only, to avoid fungus rots – EO) if we go without rain for 3 weeks.  Zoysia, Bermuda and buffalo grass can go without water all winter if they are completely dormant.

Plant sweet peas in a sunny location with a trellis.  The fragrant flowers are great for cutting. – CF

Turn off  automatic lawn sprinkler systems for less frequent winter watering. Watch and learn to water your lawn by gardener’s instinct.

Check houseplants for spider mites, which thrive in dry indoor conditions.

Prolong the life of holiday-season gift plants.  Check to see if wrapping on the container has plugged bottom drainage; remove if necessary.  Don’t over water.  Keep out of drafts from heating vents and opening doorways.

Don’t forget tulip and hyacinth bulbs in the refrigerator.   Plant after they have received 60 or more days of chilling. Lay chicken wire over the area until leaves emerge to prevent squirrels from eating the bulbs.- EO

christmas-ornament-207334_6404th WEEK:

Keep poinsettias moist, away from drafts (hot and cold), and place them in a bright room for maximum bloom length.  Again, water heavily to keep evenly moist, and check often, by feeling soil with your finger 1 inch into the soil. If dry water, if not, don’t.

Apply manure to your vegetable garden if you didn’t plant Elbon (cereal) rye earlier.

Continue to plant spinach, English peas, snap peas and snow peas.

Kalanchoes do not need as much water as poinsettias.  The soil can dry to 2 or 3 inches before watering.

Fertilize actively growing cool-weather plants such as pansies with a cup of slow-release lawn fertilizer per 100 sq.ft. of garden.  Don’t overwater pansies.  Don’t water bluebonnets.

Knock the remaining pecans off your trees with a long cane pole.  Be careful not to touch utility wires. – CF

After severe icy condition occur, prune any broken tree branches (paint wounds on oaks immediately), cut back tops of ice-withered perennials, and remove annuals killed by frost.

Deadhead old roses (just under spent bloom). Spring pruning comes in mid February around Valentines Day (Feb. 14th).

Many thanks to my contributors:

CF – Calvin Finch, Bexar Co. extension agent for horticulture, Texas Agricultural Extension Service. (courtesy S.A. Express-News)

EO – Edna Ortiz, Bexar Co. extension agent for horticulture, Texas Agricultural Extension Service. (courtesy S.A. Express-News)

LR – Lynn Rawe, Bexar Co. extension agent for horticulture, Texas Cooperative Extension Service. (courtesy S.A. Express-News)