Arizona’s December Gardening Guide

The garden transitions to a quieter phase as December arrives in Arizona’s low-desert landscapes. This phase is characterized by wise maintenance, harvest, and preparation, as opposed to the frantic vigor of the summer. It is the perfect time to establish the foundation for success in the upcoming seasons, as the weather is cooler, pests are less prevalent, and outdoor working conditions are more pleasant.

Adjustments to Irrigation and Watering

Plants necessitate less frequent watering as a result of reduced temperatures and shortened daylight hours. If there has been some rainfall, established trees and shrubs can frequently endure a period of 10-14 days without receiving a profound soaking. Pull back even further for frost-sensitive plants and containers. The current risk is overwatering, particularly if the soil remains damp for an extended period. Ensure that the soil moisture is checked prior to operating the system, and adjust the timers accordingly. The retention of warmth and the mitigation of soil temperature fluctuations over the course of the night are both facilitated by the use of mulch around plant bases.

Harvest and Clean-Up Mode

December is a month that is particularly rewarding for harvests, as the cool-season vegetables that you planted earlier, such as kale, chard, lettuce, and peas, should be thriving. Inspect the garden for spent plants, fallen leaves, or decay as you harvest, and enjoy the fresh selections. In addition to maintaining the cleanliness of the area, the removal of old foliage also serves to prevent the overwintering of pests and fungal diseases. Discard any plant material that exhibits evidence of pest or disease damage and compost healthy plant material.

Planting Trees, Flowers, and Edibles for the Cool Season

This is one of the most advantageous months to establish new vegetation. Currently, it is possible to direct sow or transplant cold-tolerant vegetables, including carrots, radishes, beets, and turnips. Numerous annual flowers, including alyssum, nemesia, snapdragons, and pansies, also flourish in the mild sunlight of December, providing winter color and early spring blossoms. Installation of new plants is advantageous for trees and vegetation during this period, as their roots can establish themselves in cooler soil prior to the onset of the full summer heat. It is advisable to postpone significant fertilizing for frost-sensitive plants, as it is important for the roots to settle before they expand into vulnerable new growth.

Protection from Frost and Cold Weather

It is important to avoid becoming complacent due to the moderate winter, as desert nights can still drop to the high 20s or low 30s. Young citrus and container plants are particularly susceptible. When a freezing is anticipated, it is advisable to have frost cloths, burlap wraps, or even repurposed grocery bags on hand to protect delicate specimens. Refrain from pruning frost-exposed growth immediately; rather, wait until the plants resume active growth in the spring before cutting the sad-looking stems in frigid weather.

Lawn and Landscape Maintenance

December is a relatively low-key month for lawns and numerous landscaping projects; however, it is an ideal time to strategize for the subsequent phase. While you are still able to work outdoors, consider replacing worn turf with a small vegetable plot or designing new hardscape features. For lawn overseeding (e.g., ryegrass in sheltered areas), it is important to plant the seed early in the month to ensure that it germinates while the temperature is still favorable. Leave spring-blooming shrubs until after their bloom period, but prune non-flowering deciduous trees while they are dormant.

Containers, Pests, and Indoor Maintenance

Pests do not vanish in December; rather, they alter their behavior. Be vigilant for mealybugs, scale, and aphids on houseplants or citrus. Pots are still rapidly dried by the arid sun, so it is important to inspect them more frequently, even though they are placed in deep water. On the coldest evenings, relocate vulnerable plants to a protected location (garage, lanai, sunroom). Give houseplants bright indirect light and maintain moderate moisture while they are indoors.

Take Advantage of the Season and Plan Ahead

In Arizona, one of the most significant gifts of December is the pleasant weather that has restored the enjoyment of horticulture. Preparing seed orders for January and February plantings, pruning your garden journal for the upcoming year, and enjoying your outdoor space. A small amount of forethought now will yield significant benefits in the future.

Summary

In December, Arizona, you transition from a state of full-on growth to one of maintenance, wise planting, and preparation. Harvest cool-season crops, sow for winter and spring, protect against cold snaps, water less, yet monitor carefully, and use the mild month to plan and appreciate the process.