April: What to Do in the Desert Garden

While there’s beauty to be found in the desert all year, April might just be the most beautiful month. And for gardeners, it’s one of the busiest, too. Here’s a look at what you can plant, what you should prune, how to adjust your watering schedule, and more.

April is unparalleled when it comes to desert beauty. Plants of all kinds — wildflowers, cactus, shrubs, and trees — are in bloom. It is also one of the busiest months for desert gardeners.

April Weather Outlook

April is a month of change, and it can get quite hot or still be chilly. But the average daytime temperatures are typically pleasantly warm, while the nights are pleasantly cool.

But for those of us who grew up thinking “April showers bring May flowers,” it can be jarring to learn that spring is the driest season and that April is the first of the desert’s three driest months.

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

April Weather Averages (Tucson)

High temperature	83°F
Low temperature	53°F
Precipitation	.39″
Relative humidity	24%
UV Index	8.5
Wind	15 mph

April Weather Averages (Phoenix)

High temperature	86°F
Low temperature	61°F
Precipitation	.23″
Relative humidity	22%
UV Index	7.6
Wind	8 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.

What To Do in the Garden in April

Here’s a snapshot of the activities you can do this month.

Read on for all the details and exceptions!

What to Plant in April

Some plants should be planted in April. April is an ideal time to plant cactus, agaves, and other succulents since warm soil temperatures encourage their root development.

It’s also a good time to plant other heat-loving plants. Bougainvillea, hibiscus, lantana, fig trees, citrus trees, and flowering vines such as crossvine and queen’s wreath fall into this category.

You can plant nearly all trees, shrubs, perennials, vines, and ornamental grasses in spring. But if you’re going to plant these in April, try to do it early in the month, weather permitting. Avoid planting during heat waves, which can now occur as early as March. Since 2020, it has become common for the first 100+ degree days to occur in April.

Other plants can be planted in April, even though it would be less stressful for them to have been planted earlier in the spring, to give them the most time to acclimate before it gets really hot, or in the fall.

You can also move plants and divide perennials and clusters of aloe now as well.

Minimize plant stress
7 Steps for Successful Spring Planting

Planting Annuals

While nurseries are well-stocked with summer annuals, resist the urge to buy them until the nighttime temperatures stay above 55°F. Here in Tucson, that’s usually in late April or even in May. Then you can plant heat-loving annuals including gaillardia, annual verbenas, pentas, moss roses, zinnia, and Madagascar periwinkle (i.e., vinca).

If you’re eager to freshen up your containers, add a few “shoulder season” plants such as dianthus, gerbera daisies, million bells, and dusty miller. Move containers as needed to adjust for seasonal changes in the position of the sun.

And it may be time to pull winter annuals that are struggling such as petunias, snapdragons, and pansies.

How to Water

By now, you should have switched over to the spring watering schedule. As the weather gets warmer and drier, plants should be watered more frequently.

Most people water too little too often. Don’t be one of them! You can refer to this chart below or use the Landscape Watering by the Numbers flipbook as an in-depth guide.

Watering New Plants

It’s critical that new plants get enough water. Here’s a good rule of thumb for watering new plants.

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

How often to water after this initial period depends on the plant. You can check for the ongoing water requirements for specific plants in our Desert Plant Library.

Not sure how to water your plants in April?
These articles can help:
7 Tips for Watering Landscape Cactus (& Other Succulents)
How to Water Desert Trees: How Often? How Much?
How to Water Desert Shrubs: How Often? How Much?

Check Your Irrigation System

If you have an irrigation system, now is a good time to make sure it’s working properly and that the placement of emitters has kept up with the growth of your plants. Trees and shrubs should be watered at their drip line, not at their trunk, and the number of emitters should increase as the plant grows.

See the Check Your Irrigation System in our March monthly guide for information on what to check and how to get professional help.

What to Fertilize

April is a good month for fertilizing many desert landscape plants that benefit from fertilizer. (Not all of them do.)

Fertilize Non-Native/Flowering Plants

While most desert landscape plants don’t need fertilizer, you may want to fertilize those that are not southwest desert natives and/or that flower profusely for extended periods.

Examples of plants that can benefit from an application of fertilizer this month include:

• flowering vines (i.e., lilac vine, snail vine, queen’s wreath, crossvine)
• flowering shrubs (i.e., hibiscus, cape honeysuckle, yellow bells)
• flowering perennials (i.e., Gregg’s mist, coral fountain, Jerusalem sage)
• any potted plants

Don’t fertilize plants immediately after planting or when they are otherwise stressed, such as during a heat wave.

Top Dress with Mulch or Compost

While I rarely fertilize my desert landscape plants, I do top them with organic mulch. You can use wood chips, they have some drawbacks. I prefer to top dress my plants with compost or composted mulch. I apply a donut-shaped ring of compost a few inches deep, keeping it away from the base or trunk.

Unlike chemical fertilizers, compost gradually adds organic matter and nutrients, and builds healthier soil by supporting beneficial microorganisms. It keeps your plants’ roots cool and retains moisture. A benefit over wood chips is that it’s less likely to float away when it rains.

Fertilize Citrus

Citrus should be fertilized three times per year and should have received their first feeding sometime in January or February. The window for their second feeding is between March and April.

There’s more to fertilizing citrus than haphazardly sprinkling fertilizer around a tree. Learn how to fertilize citrus for best results in our article How & When to Fertilize Citrus Trees.

While we’re talking about citrus, don’t fret if your tree loses older yellow leaves or drops premature fruit. Both are perfectly normal. The tree will only keep the amount of fruit that it can comfortably support.

What to Prune

It’s time to get out your pruners and loppers. If you didn’t prune cold-damaged plants in March, do it this month.

Plants that die back in the winter — perennials, ground covers, vines, and ornamental grasses — benefit from a hard prune. Some, like ornamental grasses, should be cut to nearly ground level to remove old growth while most perennials should be cut by 1/3.

Cut back vines to remove any cold damage. You can prune vines lightly or extensively as needed to control their size. Prune basal sprouts to the ground if you wish to prevent their spread.

Hand prune shrubs to shape or control size. Wait to trim spring-flowering shrubs until after they’ve finished blooming.

Prune succulents that show signs of damage or to control their size. When pruning segmented cactus like prickly pears, always prune at the joints. If you have any cactus that normally bloom in the spring, trim them after they are done blooming. You don’t want to remove any potential flowers!

You can continue to deadhead annuals to encourage flowering.

What to Do With Wildflowers?

Some wildflowers such as desert bluebells, penstemon, and native poppies may have finished flowering. You have a few choices. You can:

• Remove spent flowers now if you don’t want them to reseed.
• Leave spent flowers alone, and they may reseed.
• Harvest the seeds when spent flowers are completely dry to sow next fall.

Watch for Insects

With warmer weather comes increased insect activity. Resist the impulse to kill bugs you see on your plants until you know what they are — some of them are the good guys — while others are just part of the circle of life. Here are a few insects that might make their presence known this month.

Let’s start with a “good bug” that you don’t want to harm.

Leaf Cutter Bees

You may notice circular cutouts on the leaves of some of your plants, especially roses, redbuds, skyflowers, and bougainvilleas. These are caused by leaf cutter bees.

Leaf cutter bees are non-aggressive, solitary bees that are important pollinators, so please do not kill or discourage them.

Any damage you see is purely cosmetic and won’t harm your plant. Leaf cutter bees are quite amazing. They cut plant circles and wrap up their larvae, making “baby bee burritos.” 🙂

Agave Weevil

The agave weevil is one of the most feared and destructive insects in desert gardens. This small black bug attacks agaves and by the time you notice the damage, it’s too late to save the plant.

The first sign that an agave is struggling is that it looks droopy and yellow. The lower leaves look wrinkly, but the top remains upright. If you give your plant a gentle rock, it will easily move and even break off at the base if it’s badly infected.

While it will be too late for that plant, you can learn about the steps you can take to stop its spread and prevent future infestations here.

Genistra Broom Moth

If you grow Texas mountain laurel, look for genista caterpillars, the larval stage of the genista broom moth.

They like to dine on new leaves and young seed pods. Learn how to recognize and deal with an infestation here.

Manage Weeds

Depending on how much winter rain you’ve had, you’ll almost certainly have some weeds pop up this month. My first-line strategy for keeping weeds at bay is to pull them when they’re young, and the ground is wet. My second-line strategy is to spray them with straight household vinegar on a hot sunny day.

You can keep the number of weeds down dramatically by following this simple rule:

Get rid of your weeds before they seed.

When a weed is left to go to seed, it can produce hundreds or thousands of seeds — which become next season’s weeds.

If you sowed wildflower seeds in the fall or hope some of your garden plants will reseed, be sure you aren’t pulling any seedlings of plants you want in your yard. 😉

Stinknet

Stinknet is a weed that’s in a category of its own. It’s bad news even in its native South African habitat. But in the desert southwest, it’s an alarmingly aggressive, invasive plant that threatens desert biodiversity, contributes to wildfires, and emits toxic gases when burned.

Every gardener should know how to ID it, what to do if you find any, and how to get rid of it safely. To learn more, watch this video or visit Stinknet.org.

Upcoming Gardening Events in April

There are loads of gardening classes and events throughout April. You’ll find a comprehensive list of nurseries, botanical gardens, and organizations that regularly hold classes, events, and sales so that you never miss out in our Tucson Gardening Event Guide.

The Pima County Master Gardener Home Tour is held this month. Get your tickets soon because they sometimes sell out. They also hold their semi-annual plant sale this month.

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

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Photo Credits

AMWUA.org

“Megachile Centuncularis” by JRxpo is licensed under CC BY 2.0

Nanosancho, CC BY-SA 3.0, Wikimedia Commons

Stinknet.org