December: the Full Garden List
Gardening often, and should, be less of a priority during the holidays. The colder weather has slowed growth and hopefully is providing enough moisture to reduce the need to irrigate. Use this time to enjoy the results of your labors and spend time in the garden with friends and family.
Planting, Transplanting, & Care
- Plant hardy perennials, shrubs
- Plant trees
- Plant roses
- Plant winter annuals, including Calendula, Snapdragon, Pansy, Viola, Dusty Miller, ornamental and flowering Kale & Cabbage, Alyssum, Stock, Cyclamen
- Plant Spring Bulbs to the first week of December
- Avoid planting tender plants like Pride of Barbados, Esperanza, Lantana, and Plumbago
- Roses: Grafted roses are not as cold-tolerant as own-root roses and need to be protected from a hard frost. Mound up straw or soil around the root zone as insulation. Keep your roses watered during the winter if there are no sufficient rains.
- Evergreens: All evergreen plants still lose water through their leaves during the wither. Continue to water them through the winter if there is not sufficient rain.
- Ornamental Grasses: You can largely leave your ornamental grasses alone until early spring. If native grasses are looking a little drab, glove up and give them a fluffing with open hands, going in an upward motion to remove dead leaves. This is especially effective for Muhly grasses.
- Plant Perennial Thyme, Oregano
- Avoid planting Rosemary
- Plant Cilantro transplants, Parsley, Dill, Fennel, Chervil, Summer Savory, Borage, Rue, Chives
- Be prepared to cover in case of deep freeze.
- Plant Asian Greens, Bok Choy, cool season Greens, Lettuce seeds or transplants, Radishes, Spinach seeds or transplants
- Pay attention to the forecast. If temperatures are predicted to fall below 28° cover plants with row cover, securing edges with soil, bricks, rocks or pins. Plant small flats of broccoli, cauliflower, kale, mustard, collards and cabbage for transplanting in mid-January. Start shopping for seed potatoes and order for the February planting season.
- Our average first frost is November 15, but sometimes occurs earlier. Many root vegetables such as turnips, carrots, and parsnips sweeten after a frost or two. Parsnips need this cold treatment for the best flavor and can stay in the ground for a month after frosts start.
- Keep planting winter crops in small batches for successive harvest.
- Water weekly with liquid seaweed for strong root establishment.
- To prune freeze damage plants or not: Best to leave seeds on plants for birds and to protect the root system.
- Avoid pruning shrubs unless you see damage.
- Do not prune oak trees unless you have damage; paint the wound immediately.
- Okay to prune trees other than red oaks and live oaks.
- Use mind days to turn compost and build up mulch.
- Add a thin layer of compost over newly-planted groundcovers and vines.
- Continue to feed vegetables with fish emulsion or other water-soluble fertilizer every two weeks. Soil microbe activity slows down in the cold so supplemental fertilizer may be needed. There is no need to fertilize other types of plants.
- Shrubs, roses, trees, evergreen spring-blooming perennials while dormant
- Asters and other fall-bloomers while dormant
- There is not much to do with your lawn once November and cold temperatures hit. The grass generally goes dormant and you needn't mow. If you must mow, keep high to shade out germinating weeds.
- Pluck out early weeds before they have a chance to put down roots.
- Use a mulching mower instead of raking leaves.
- You also will not need to fertilize or use pre-emergents as they would stimulate new growth that could freeze off. You can amend lightly with compost to add a bit of insulation and decompose very slowly over the winter.
- Continue to water depending on rainfall. More grass dies from dehydration than from cold in winter. Water before you expect a frost to protect roots in the cold.
- As you will not be watering that often, now is a good time to inspect your sprinkler system. Replace any damaged heads.
- Water vegetables so that plantings do not dry out. Check the soil first, irrigate only if the soil is dry a few inches below the surface or in newly-established seedbeds. Water everything well before a freeze, but avoid overwatering.
Pests, Wildlife, & Diseases
- Many birds are migrating during this time. Consider putting out a bird feeder with sunflower seeds, millet, dried fruit, and suet to feed local songbirds. Keep bird feeders away from death zones like tall grasses or bushes, ledges, or wall corners to keep our feathered friends from outdoor cats. The higher the better.
- Leave seeds on plants for birds.
- Insects are not much of a problem after the first frost hits. Take advantage of outside time with no mosquitoes.
- Look for dead, dried fruit or blossoms called "mummies" on fruit trees, vines, and bushes. Remove and throw in the trash, not the compost. Remove all fallen fruit.
- Check for leave spots on roses. If there are signs of fungal disease, remove the leaves off the stem and rake the fallen leaves together for disposal. Do not compost.
- Continue to acclimate your plants, so they get used to the decreased light and humidity. This can help prevent leaf drop. Gradually increase the time indoors until they are inside all of the time for the season.
- Place tropicals and other houseplants in a sunny southern window or greenhouse.
- Decrease the amount of water your plants receive while they are inside. Make sure you put a drip tray down to protect your flooring. Water only when the soil is dry and be careful not to flood the drip tray.
- Refrain from fertilizing, but depending on the plant, use a small quantity of slow-release fertilizer or a half-strength liquid fertilizer.
- Diseases/Pests: Pest insects are more likely to be encountered on indoor plants than disease because the interior environment rarely offers favorable conditions for foliar diseases to develop. However, when plants are grown under stressful indoor conditions (such as lower light, lower humidity, and excess water) soil-borne pathogens often develop.
- Protect your poinsettias from cold and allow them to dry out slightly between water
Other Tasks & Prep
- In the Shed
- Clean your gardening tools.
- Sharpen blades of shovels, trimmers, and loppers.
- Apply a thin coat of machine oil to lubricate moving parts and prevent rust, especially on pruning sheers.
- Use diluted bleach to disinfect trimmers to prevent spread of diseases.
- Treat wooden handles with linseed oil.
- In the Yard
- Select spots where you want fruit trees, grapes, or berries to plant in January; for now, prep with compost.
- Rake leaves into beds to mulch over winter and return nutrients to the soil. Use excess leaves in compost.
- December usually means storms for Central Texas, so periodically keep your garden beds clean by picking up downed branches and debris.
- Prepare for the freezes by insulating faucets and draining garden hoses.
- Check gutters for debris so they may do their job properly in the rainy season.
- Consult your owner's manuals for information on winterizing your lawnmower and other engine-powered equipment.
- In the Greenhouse
- Collect seeds from summer annuals to dry and store indoors until next spring.
- Keep new seedlings moist but not drenched.
- Clean greenhouse, pots, and trays thoroughly.
- Keep an eye out for aphids overwintering on your plants, and remove by hand or high-pressure hosing.
- Ventilate the greenhouse on warmer days to reduce humidity and risk of disease.