Sunny days, with average highs in the mid 60’s and lows in the 40’s, mean that Tucson desert dwellers have a unique
opportunity to garden in January while the rest of the nation is largely covered in a blanket of snow. This pleasant weather
makes it an ideal time to tackle annual maintenance or some of the more physical activities on your to-do list. Continue to
keep an eye on nighttime low temperatures and protect cold-sensitive plants. Review your irrigation settings if rainfall is
generous. And tell your friends in cooler climes about all the things you’re planting this month!
Maintenance
- Stay on top of garden cleanup.
- Winter rains bring weeds – be vigilant! Suppress their germination by applying thick layers of mulch such as wood chips or
straw. Regularly pull weeds as they emerge. - Do the annual check and repair of your irrigation system(s).
- There are several pruning activities that are important to complete in January and February. Here are some guidelines:
- Trim deciduous fruit trees and shrubs this month while they are dormant.
- Other deciduous trees, such as Arizona Ash, can also be pruned. As a minimum, remove broken or crossing
branches, but never more than ¼ of the total branch area. - Grapevines can be pruned now through mid-February. Follow pruning of the dormant vines with a thorough,
drenching spray of horticultural oil. This is a first step in managing overwintering pests such as grape leaf
skeletonizers. - Prune established roses beginning in the middle of the month. Cut canes back by 1/3 to 1/2, just above outwardfacing buds (not those aimed toward the plant’s center). Newly planted specimens (see below) are not pruned.
- Do not prune citrus unless branches are broken or impeding a pathway.
- Do NOT prune frost-damaged plants yet. Even frozen branches will protect the plant somewhat. In mid-March when
plants begin to leaf out, you will be able to tell what part of the plant is still alive. Do not prune spring-flowering plants
until after they bloom. - Be prepared for frost and freezing temperatures:
- Know your USDA Plant Hardiness zone; it helps localize your temperature expectations for plant protection.
- When freezing temperatures are predicted, cover frost-sensitive plants with frost cloth or old sheets. Never use
plastic. In Tucson, March 15 is considered the average date of the last frost, so do not be fooled by moderate
temperatures. Your “last frost” date may be later if you live at higher
elevations or in a cold valley. - If a frost or freeze is forecast, cap cold-sensitive cacti, such as totem pole, golden torch, Mexican fencepost, and
young saguaro. Use a paper grocery bag or large Styrofoam cup to protect the delicate growing tip from the cold.
Do not use plastic in direct contact with the plant; it will conduct cold not insulate. After the freeze, remove the
cap, but keep it – you can reuse. - Pick exposed lemons and limes before a hard freeze. Some damage to these fruits on upper and outer portions of
the tree will occur when temperatures drop to 28 degrees. Other types of citrus fruits can handle cold
temperatures better.
- Consider planning or installing active or passive rainwater harvesting.
Planting
- Plant bare-root deciduous fruit trees such as apple, apricot, peach, and plum trees.
- Prepare vegetable and flower beds for spring planting. Plant artichoke crowns, asparagus, cane berries, onion sets, and
bare-root strawberries into the ground. Importantly, when buying strawberries or other plants as “bare root” (not rooted
transplants which do not get planted now) from local nurseries or big-box stores, be sure the roots are moist and viable –
and that they remain that way until planted. - Plant seeds into the ground for vegetables such as beets, carrots, radish, leafy greens, peas and onions, as well as cool weather flowers such as stock, snapdragons, pansies, and alyssum.
- Start seeds indoors for tomatoes, peppers, and eggplant.
- Plant bare-root roses. Purchase only high-quality plants from reliable garden centers. The planting bed must be amended
with organic matter such as compost, peat moss, or aged manure to a depth of 18”. Be sure your soil drains well and that
the swollen graft union near the base of the canes is above the soil level.
Fertilizing
- Continue with mild fertilizing of winter vegetables. There are various fertilizer options, including organic and chemical
fertilizers. When using organic fertilizers, it's important to apply them early to allow sufficient time for breakdown, ensuring
a steady nutrient supply as plants grow. - Bearded iris may be fertilized toward the end of the month. Scratch fertilizer into the soil near the bulbs and water in
thoroughly. - Other uses of fertilizer are not advised. Fertilizers stimulate new growth that will be frost sensitive.
Watering
Wildflowers planted in the fall may require supplemental watering if winter rains do not cooperate.
If there is little rain, some trees and shrubs may need additional watering. Deciduous trees only need water if the drought
of rain is extended.
More Information
Training and pruning fruit trees
Growing Grapes in the Home Garden
Problems and Pests of Agave, Aloe, Cactus and Yucca
Protecting a Citrus Tree from Cold
Ten Steps to a Successful Vegetable Garden
Landscape management practices for passive water harvesting
Flower Planting Guide for the Low Desert
Rose Selection and Planting in the Low Desert
Fertilizing Home Gardens in Arizona
Extension Publications
For more information on any of these topics, search our database of Extension publications going back more than 100 years housed in the University of Arizona Campus Repository.