January: What to Do in the Desert Garden

January is the second coldest month, but there are still plenty of things to be done in the desert garden. Here’s a look at what you can plant this month, how to adjust your watering schedule for winter, how to care for holiday plants, and more.

January is one of my favorite months in the desert. I find myself comparing the weather to that of other places I’ve lived (like Chicago, New York, and Baltimore 🥶) and feel grateful that I managed to wind up in my idea of paradise.

The weather in January is nearly indistinguishable from December’s, and consequently, the garden “to do” list is similar. (You can expect some of the information here to look familiar if you’ve read December’s Gardening Guide.)

January Weather Outlook

There’s not much of a change in the weather since last month. The average highs and lows in Tucson and Phoenix are surprisingly, around 1 degree warmer than December’s. But the sun continues to get less intense — the average UV index in January is the lowest of the year.

Here’s a look at January weather averages in both Tucson and Phoenix.

January Weather Averages (Tucson)

High temperature	67°F
Low temperature	41°F
Precipitation	1.00″
Relative humidity	46%
UV Index	2.7
Wind	13 mph

January Weather Averages (Phoenix)

High temperature	68°F
Low temperature	46°F
Precipitation	.88″
Relative humidity	42%
UV Index	2.3
Wind	6 mph

If you live elsewhere, enter your city or town in the search bar at TimeandDate.com to find your weather averages. And you can find your average UV index at UVIndex.io.

January Gardening Tasks

Here’s a snapshot of the tasks you can expect to do (or not do) this month. (I’ve marked the changes from December’s task with an asterisk*.)

Read on for all the details and exceptions!

Be Prepared for Frost

By January, it’s very likely that you will have experienced frost in your garden. If you haven’t already done so, here’s what you need to know when deciding what plants need protecting.

Figure Out What Plants Need Protecting

Don’t assume that all your plants need protecting. Most desert landscape plants don’t need cold protection, especially if they are native. And it’s rare that a mature plant needs protecting — if it’s made it this far, it should continue to be OK!

You can find out which plants are frost-sensitive by referring to your favorite gardening book or online resource. I hope our Desert Plant Library is one you have bookmarked. (Currently, there are over 70 of the most popular plants there and I add more every week.)

Know Your Precise Temperature Forecast

Second, follow the weather as close to home as possible. Typical weather forecasts will tell you what to expect at the airport — but I doubt you live or garden at the airport! I use Weather Underground which offers over 60 weather stations in Tucson to pick from.

To find your nearest station, type your city or town in the search box, then click on “Change” and you’ll be presented with a drop-down list of “Nearby Weather Stations.” Review the map and choose the weather station nearest you.

I also suggest putting a thermometer or two in various spots in your yard to track your microclimates. Seeing how consistently cooler or warmer some locations are can be enlightening. Knowing this can make the difference between having to cover certain plants or not.

Not sure of your “Zone” or why it matters?
The Importance (& Limitations) of Knowing Your USDA Hardiness Zone

Be Ready to Cover

Third, have what you need to protect your plants before you need it. It’s not unusual for local hardware stores and nurseries to run out of frost cloth when there’s an impending freeze.

You don’t have to use frost cloth. Many gardeners improvise with sheets or burlap, but frost cloth has some advantages. It lets in air and light, can be left up for days, and if there’s rain, it dries fast and doesn’t weigh your plants down. Towels and blankets can be too heavy for some plants.

Frustratingly, cold fronts are often accompanied by wind and sometimes rain. So do a practice run to figure out how you’ll secure your coverings ahead of time. You don’t want to find your frost cloth in your neighbor’s yard the morning after a freeze. (Yes, I’ve had that happen.) 🫣

Covering (and Uncovering) Cactus

It’s not unusual to see columnar cactus tips covered with red cups or small Santa Claus hats for the holidays. Some people do this for decoration while others are trying to protect the tender tips from frost. Not all cactus need protection but totem pole, fence post, and young saguaros are among those that benefit from frost protection.

Cloth hats, paper bags, or styrofoam cups are good choices, but don’t use plastic cups! Plastic does not insulate — it conducts cold — and can cause more damage than leaving tips bare.

If you put hats on your cactus for Christmas, remove them now.
Ideally, cactus tips should not be covered for more than a few days in a row.

What To Do in the Garden in January

While a lot of tasks are on hold, or minimized, this month, there are still ways to keep busy in the garden if you choose to.

What to Plant in January

Surprisingly, there are a handful of things that can be planted in January.

• cold-weather annuals
• live Christmas trees
• bare root roses and deciduous trees
• cold-weather herbs and vegetables

Winter annuals planted now — pansies, snapdragons, alyssum, lobelia, stock, dianthus, geraniums, and petunias — can still be enjoyed for the next four months or so. Then it will be time to replace them with summer annuals.

If you have a live Christmas tree, January is the time to get it in the ground. Plant it in a hole as deep as the root ball (no deeper) and three times as wide.

Watering New Plants

If you planted any trees or shrubs in November or December, continue to water them according to this University of Arizona recommended schedule for 8 weeks total.

Weeks 1 & 2	Every 3 – 4 days
Weeks 3 & 4	Every 5 – 7 days
Weeks 5 & 6	Every 7 – 10 days
Weeks 7 & 8	Every 10 – 14 days

Water Established Plants on a Reduced Winter Schedule

By now, you should have drastically cut back on watering frequency for all your established plants. Most trees and shrubs only need water about once a month in the winter.

You can stop watering succulents such as cactus, agaves, aloe, hesperaloe, and desert spoon this month. Winter rains normally provide adequate water between fall and spring. But continue to water potted succulents once a month for the next few months.

Not sure how to adjust your watering schedule for January?
These articles can help:

How to Water Desert Trees: How Often? How Much?

How to Water Desert Shrubs: How Often? How Much?

Watering Before a Freeze

Most plants benefit from watering before a freeze. The exceptions are cactus and other succulents which are more likely to suffer freeze damage if they’ve been recently watered.

What to Fertilize

Don’t fertilize any landscape plants in January. Feeding them now can encourage new frost-sensitive growth. However, you can still fertilize flowering annuals once a month.

What to Prune

By the second or third week in January, you can start pruning dormant deciduous trees. Once they’ve lost their leaves, you can more readily see their branch structure to determine what needs pruning. Pruning now won’t stimulate new growth and minimizes dripping sap.

This is also time to prune established roses by one-half to two-thirds.

You can prune any dead or broken branches, suckers, or water spouts on shrubs or trees anytime, especially if they pose a hazard.

You can continue to deadhead annuals to encourage flowering.

Don’t prune frost damaged growth on any of your plants until the danger of frost has passed.

Harvest Your Citrus (Maybe)

Depending on your microclimate and the variety you’re growing, some citrus may be ripe this month. Color is not the best way to determine if citrus is ripe. When ripe, fruits should have a pleasant citrusy smell and have some heft when you hold them.

If you suspect your fruits are ripe, pick one and give it a try. It’s the only way you’ll know for sure. And remember that citrus, once picked, does not continue to ripen.

And don’t be in a hurry to pick oranges and grapefruit since “The longer on the tree, the sweeter it will be.” 😋

How to Care for “Holiday” Plants

Now that the holidays are over, it’s time to decide on the fate of your poinsettias or other holiday plants. Non-gardeners usually treat them like cut flowers — enjoy their temporary beauty and toss after the holidays.

But if you want to keep yours growing all year, check out Green Things’ poinsettia care guide. Their instructions will tell you how to care for your plant and how to get it to bloom next winter, if you’re up for the challenge.

Christmas cactus, cyclamen, kalanchoe, and amaryllis are other traditional holiday plants that can continue to be grown all year either indoors or outdoors with some protection. Like poinsettias, they require special care if you want them to bloom again next year. Learn how to care for these plants after the holidays here.

Upcoming Gardening Events in January

After a slight holiday lull, gardening classes and events are picking up again. You’ll find an up-to-date list of gardening-related events in our Tucson Gardening Events Calendar.

Don’t live in Tucson? Look for Zoom classes. You can participate in these no matter where you live.

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