In December, the weather in Phoenix is cooler, the mornings are crisp, and the outdoor weather is some of the best of the year. Even while the Valley doesn’t get frigid winters like other regions of the country, plants nonetheless grow more slowly, need more water, and some landscaping activities become easier or more important. Here are the best Phoenix gardening and tree-care ideas for December 2025 if you want your garden to do well this winter and come back strong in the spring.
1. Change the times you water your plants
Overwatering is the most typical mistake in December. Plants need a lot less water when the nights are cooler and the days are shorter. Most trees and shrubs that can live in the desert only need to be watered every 14 to 21 days. You might need to water citrus trees a little more often, but not nearly as much as you do in the summer.
When you water, make sure to soak the soil deeply but not too often to let the roots grow strong. When you water trees too shallowly, they grow weakly and are more likely to get cold in the winter.
2. Keep plants that don’t like the cold safe
Phoenix doesn’t freeze very often, but some communities, especially in north Scottsdale, Cave Creek, Ahwatukee, Queen Creek, and regions with higher elevations, can get temps in the low 30s.
Keep weak plants safe, like:
- Lantana
- Bougainvillea
- Hibiscus
- Citrus trees that are still young
Use frost cloth, old sheets, or plant blankets that let air through (never plastic). Put a cover on in the late afternoon and take it off in the morning when it gets warmer.
3. Only prune when it’s necessary
Most trees shouldn’t be heavily pruned in December. In the winter, cutting too much might stress plants and make their new growth more likely to get cold damage. Don’t prune:
- Citrus
- Mesquite
- Palo Verde
- Oaks that live
- Trees with palms
But it’s a terrific time for:
- Taking off branches that are dead, broken, or weak from storms
- How to shape trees that lose their foliage
- For safety or visibility, light thinning
- January and February are usually ideal months for substantial pruning.
4. Plant flowers and vegetables that bloom in the cool season.
In December, your winter garden will be full with bright colors. Some great flowers for the chilly season are:
- Pansies
- Violets
- Snapdragons
- Stock
- Dianthus
Put in the vegetable beds:
- Lettuce
- Kale
- Spinach
- Broccoli
- Carrots
- Radishes
These do well in Phoenix’s warm winter and make a lot of fruit in February and March.
5. Use mulch to keep the soil warm.
A new layer of mulch helps keep the soil at the right temperature, hold in moisture, and protect the roots. Put 2 to 3 inches of mulch around trees and garden beds, but don’t let it touch the base of the trunks.
6. Set up tree health checks
December is a great time to have a licensed arborist check the structure of your trees, the health of their roots, and their readiness for storms, especially before the windy winter systems come in January.
Arbor Care can help you with pruning, deep-root feeding, analyzing your soil, and giving you advice on how to safeguard your trees in the winter.
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