December Gardening Checklist

by Anthonyfamilyinfo@gmail.com
Texas Native Holly

December is one of the best months, do you agree? Well, they are all good, but so many fun things to do in December and memories to make. Is there any time left to garden? Is there any gardening to be done? Of course, there is!

This begins the time of year to assess your landscape, recall any issues and explore solutions.  Are there any changes you wish to make? Does anything need to be added or replaced? While there may be fewer garden chores in December, as Kipling said, “gardens are not made by sitting in the shade and singing all day.” There are a few tasks to do this month for central Texas gardens that will pay off in the coming months.

What can be planted in December?

Plant trees and shrubs. Planting and transplanting woody ornamentals in the coolest months of the year allows their roots to become more established before the heat of summer. A water soluble, high nitrogen root stimulator is beneficial for new trees and shrubs. Soil should be kept consistently moist, but not overly wet.

Before deciding on a tree to plant, measure the area. Then, select a tree with a mature size that fits the space. The most common blunder in home landscapes is planting trees that grow too large for a space and are too close to structures.

Some trees for central Texas landscapes by size are:

  • Large – Live oak, Bur oak, Chinkapin oak, Bald Cypress, Mexican Sycamore, Pecan
  • Medium – Mexican White oak, Lacebark elm, Eastern Red cedar, Carolina Laurelcherry
  • Small – Crapemyrtle, Chinese Fringetree, Redbud, Mountain Laurel, Desert Willow

Texas has an exceptional tree resource in the Texas A&M Forest Service. See their Texas Tree Planting Guide.

What flowers and vegetables can be planted in December?

Spring flowering bulbs should be planted by the end of the month – Spanish bluebells, daffodils, grape hyacinth, narcissus and summer snowflake. Note, that tulips and Dutch hyacinths must be pre-chilled at 45 degrees for at least 45 days prior to planting. Texas winters are typically not cold enough to meet their chilling requirements for flowering.

Annuals that are cold-hardy brighten a winter landscape. Plant calendula, dianthus or pinks, ornamental cabbage and kale, pansies, petunia, snapdragons, stock, sweet alyssum and violas.   

  • For continued growth and flowering, fertilize annuals every 2 to 3 weeks.

What Vegetables and Herbs Can Be Planted in December?

Herbs to plant in December are thyme and oregano. Also, borage, chervil, chives, cilantro transplants, dill and fennel. Be prepared to cover to protect during a hard freeze.

While October is the ideal time to plant many cool season vegetables in central Texas, if the forecast is agreeable, some vegetables can be planted. Leafy greens, like lettuce can be grown in containers, if you don’t have garden space or raised beds.

These are the planting periods for vegetables by seed and *transplant for zone 9a (formerly zone 8b) central Texas. Adjust planting times for your USDA zone.

Week 1, 2, 3, 4 – beets, *Bok choi, *broccoli, *Brussels sprouts, *Cabbage, carrots, *cauliflower, *collard greens, *kale, *kohlrabi, lettuce, onion sets, *mustard, spinach, *Swiss chard, turnips

Nurseries may still have transplants of arugula and lettuce. If not, start seeds indoors to have transplants for January of arugula, collards, kale, lettuce, mustard greens, spinach

Onions and potatoes – If you grow onions or potatoes, check local sources now or order onion sets and seed potatoes. In central Texas, onions are planted typically in January and potatoes in February.

Plant fruit trees, such as peaches while they are still dormant. Planting in early winter gives more time for roots to establish before bud break.

Protect Plants during cold weather

Be prepared to protect plants during periods of extremely cold weather. Soil moisture is important because water protects and insulates roots from cold damage. If soil is dry before a hard freeze, water lawns, landscape plants and containers. 

Check the mulch on all woody ornamentals and tender plants. A 3 to 4 inch thick layer of mulch insulates roots from cold temperatures. Shredded hardwood, pine straw and shredded leaves are all good landscape mulches.

Cover cold tender plants with a lightweight frost cloth during a freeze. When used correctly it can modify temperatures by six to 10 degrees. Completely cover the plant with frost cloth. It must be kept secure with heavy objects like bricks so that the cloth makes complete contact with the ground. Purchase it now to have on hand. If cared for, it can be used for many seasons. Note that plastic used as a covering can heat up in sunshine and actually damage foliage. Here is the frost cloth I use.

After a frost or hard freeze, some plants will be damaged. If vegetable plants have major damage, clean that up. Damaged growth on tropical plants such as cannas, elephant ears, or gingers may be pruned away.  

Pruning of flowering perennials such as aster, lantana, plumbago or salvias can be delayed until January or February in central Texas. If you prefer a more-tidy look, they can be pruned.  

Waiting to prune plants like ornamental grasses provides winter cover for garden critters and allows some protection to the crown or growing point of the plant. Depending on weather in central Texas, pruning begins in earnest in mid-February, around Valentine’s Day. Prune most perennials down to 2 to 3 inches above the ground, then cover the crown with 4 to 6 inches of mulch for protection from cold.

For evergreen shrubs, it is best to wait until late winter to prune and shape.

November through January is a good time for tree maintenance in central Texas. Prune dead limbs and branches from trees that could be broken off in wind during a storm.

 

  • Prune dead branches of deciduous trees.
  • Corrective structural tree pruning may be done when trees are dormant
  • Remove mistletoe when it is easy to see after deciduous trees drop leaves. Use a pole saw to remove clusters. This may not get rid of mistletoe completely, but removing it reduces reproduction and the spread of the seeds. 

House plants and tender plants brought indoors for the winter should be kept slightly moist. They may grow slower in winter, so less fertilization is needed. Inspect indoor plants occasionally for mealy bugs or scale insects. If you find insects, dab them with a cotton swab dipped in alcohol to keep the population down. It can be hard to get rid of them, especially mealy bugs.

Holiday amaryllis need only small amounts of water, as do paperwhites and other seasonal bulbs grown indoors. Poinsettias should be kept out of drafts, away from heat and don’t allow them to wilt. Water deeply when the top of soil feels dry to the touch. Cyclamen should be bottom watered, just set them in a bowl or container of water for roots to soak it up.

Turfgrass

Mow the lawn one more time if needed for a neat appearance and to cut back winter weeds. Most leaves have probably fallen. Instead of raking, bagging and sending them to the landfill, simply mow to shred them. They can then be left on the lawn to slowly decompose, as natural fertilizer. Shredded leaves make a good mulch or simply compost them. But, don’t let the fallen leaves remain on the lawn all winter. An overly thick layer of leaves may weaken turf and promote disease in the spring. 

Reset your sprinkler system for winter watering. Be prepared to protect hose bibs and watering hoses during freezing weather.

Winter weeds are showing up in lawns. Clover, dandelions, henbit, chickweed and other non-grassy weeds can be controlled by a spray with a broadleaf herbicide. Read and carefully follow label directions for use.

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