The merciless heat and aridity of June make it the hardest month on plants, and the most challenging for desert gardeners. Discover what you should and shouldn’t do in the garden this month, how to water, pests to watch out for, and more.
It’s been said that “April is the cruelest month,” but that’s not true in the desert southwest, where June is the month that’s uniquely hard on plants and wildlife. Here in southern Arizona, it’s the hottest month of the year, and we often haven’t had significant rainfall for months, so plants are stressed to their limits.
If there’s one word that sums up what gardeners need to do this month, it’s “protect”. Protect your plants from heat, sun, and dehydration.
Don’t be disappointed if your plants don’t look their best or flower much this month. They’re putting their energy into surviving, and if newly planted, establishing their root system.
June Weather Outlook
Compared to May, June is even hotter, drier, and harder on plants (and gardeners). The average high is nearly 10 degrees hotter. The chance of rain goes up slightly in Tucson, and down slightly in Phoenix. Low humidity, dry winds, and increasing sun intensity continue.
Historically, the 10 hottest days in Tucson have all occurred in June, and there’s every reason to believe this trend will continue.
Here June is neither spring nor summer — it’s considered “arid foresummer“, the hot, dry period before the monsoon kicks in. By mid-June, we are teased by the possibility of rain from the monsoon, which officially starts June 15. But the first rain of the season often doesn’t fall until July.
Here’s a look at June weather averages in both Tucson and Phoenix.
June Weather Averages (Tucson)
| High temperature | 101°F |
| Low temperature | 71°F |
| Precipitation | .28″ |
| Relative humidity | 18% |
| UV Index | 11.1 |
| Wind | 15 mph |
June Weather Averages (Phoenix)
| High temperature | 105°F |
| Low temperature | 79°F |
| Precipitation | .03″ |
| Relative humidity | 15% |
| UV Index | 10.2 |
| 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.
Get Ready!
Check out Heat Wave Survival Tips for Desert Gardens
before the next heat wave hits.
What To Do in the Garden in June
Your garden goal for June should be to simply keep your plants alive, especially any that you planted this spring. The two main things to do this month are to keep your plants hydrated and protect them from too much sun.
Here’s a snapshot of the activities you can do this month and those you should stop doing.
| ✅ | Plant summer annuals |
| ✅ | Sow wildflower seeds |
| ✅ | Water! |
| ✅ | Fertilize palms, some citrus |
| ✅ | Watch for pests |
| ✅ | Watch for heat stress |
| ❌ | Don’t plant most plants |
| ❌ | Don’t prune most plants |
| ❌ | Don’t fertilize most plants |
Read on for all the details and exceptions!
What Should (& Shouldn’t) Plant in June
What can you plant in June? Hint: not much.
The list of what you can plant in June is a short one. The window of opportunity for planting in the spring has passed. (The best time to plant most landscape plants is actually in the fall, so you have that to look forward to.)
Even the exceptions — the few plants that prefer late spring planting — ideally should have been planted by May.
Landscape plants that are extremely heat tolerant (palms, cactus, and other succulents), can be planted this month, but it’s not ideal. If you must plant them now for some reason, be sure to provide them with shade. Surprisingly, even cactus and succulents can get sunburned, so protect them from the sun during their first summer.
You can still plant heat-loving summer annuals, ideally before mid-June. Sun-loving annuals you can plant now include celosia, gomphrena, moss roses, vinca, and zinnias. Shade-loving annuals you can plant in June include begonias, impatiens, and coleus.
According to Harlow Gardens, Tucson’s oldest family-owned garden center, their consistently best-selling summer annual is vinca (Catharanthus roseus), also known as Madagascar periwinkle. Their customers love it because it flowers profusely all summer long, has attractive green leaves, and can take the heat.
You can also sow summer wildflower seeds now, which germinate in response to the monsoon rains. These plants grow fast and will bloom this summer. Here are some places that sell and ship desert wildflower seeds, including “monsoon seed mixes” which contain favorites such as Arizona poppy, blanket flower, and desert zinnia.
Watering is Critical!
The most important task in June is to keep your plants adequately watered. Even landscape cactus and succulents should be watered once or twice in June, unless there’s been rain.
If you haven’t adjusted your watering schedule for the summer yet, do it now. If you look at various watering charts, like the one below, you’ll notice that summer is considered “May through October.”
As we’re facing the hottest time of year, it’s critical that you water your plants correctly. Use the University of Arizona’s Recommended Watering Schedule as a simple guide or Landscape Watering by the Numbers flipbook as an in-depth guide.
For more help on watering your plants in June,
check out our Desert Watering Resources.
Most potted annuals need watering daily.
If you’re watering with a hose, always check the water temperature. Water from a hose can be hot enough to damage your plants. And while you’ve got your hose out, if you haven’t had any rain for a while, give your plants a quick shower to remove pore-clogging dust and prevent dust-loving spider mites.
If you haven’t already done so, give your irrigation system a good once-over. This is especially important if you travel during the summer. Irrigation system problems tend to crop up when you go out of town — ask me how I know this. 🙄
Now, before the monsoon, is an excellent time to get serious about rainwater harvesting. Here’s my simple setup. It consists of three parts — a 50-gallon rain barrel, a stand, and a diverter kit to direct the water from the downspout into the rain barrel. I chose this flat back rain barrel because it was a great price, and it takes up less space than a round barrel.
What to Fertilize
June is not the month to fertilize most desert plants. It further stresses plants by encouraging new growth which is easily burned by the intense sun. And if you happen to overfertilize, especially if you use a synthetic fertilizer, you can cause fertilizer burn.
The exceptions are plants in containers, palms, and some citrus. Potted plants benefit from a dilute solution of fertilizer every two weeks throughout the summer.
If you didn’t fertilize your palm trees in May, you can still fertilize them now. Learn more about fertilizing palms and what to look for in a palm fertilizer here.
According to the latest citrus fertilizing guidelines, oranges and grapefruit should be fertilized in May or June, so now is the time to give those plants their third (and final) feeding of the year, if you haven’t already done so.
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.
Watch for Citrus “June Drop”
While we’re on the subject of citrus, you may notice that your trees are dropping some of their immature fruit this month. This is a phenomenon known as “June drop.” It’s a normal response for the trees to shed fruit they can’t comfortably support.
However, if you notice this happening, you can help your tree hold onto fruit by making sure it’s adequately watered and fed. High temperatures and low humidity contribute to the problem as well.
What to Prune
Pruning should generally be avoided. It further stresses your plants by exposing interior growth to sun and stimulating new, sensitive growth.
But there are a few light trimming tasks you can do now.
If you have trees that are sending up suckers, go ahead and remove them now.
If you have palm trees, you can remove dead fronds, but you don’t have to. Dead fronds shade the trunk and help keep their roots cooler. (Fronds that have any green should be left as they are still able to photosynthesize and support the tree.)
If you have a yucca, agave, hesperaloe, desert spoon, or other succulent that has sent up a large flower stalk, leave it up for pollinators as long as is reasonable, and remove the spent flower stalks after the flowers have dried. Of course, if a 40-foot agave stalk is in danger of falling on your house or car, be safe and remove it sooner.
Deadhead annuals and pinch back lantana to encourage flowering.
Watch for Garden Pests
If there’s one good thing about gardening in June, it’s that weeds are rarely a problem, until the monsoon kicks in.
You might find rabbits, birds, or javelinas eating your plants in June. Now that wild plants are drying up, your landscape plants are looking pretty tasty.
Check your plants for spider mites. Spider mites thrive in hot, dry weather when plants are dusty, and multiply rapidly this month. Signs of spider mites on your plants are:
- tiny black specks that look like pepper
- white webbing
- white or yellow speckled leaves
- overall dull appearance.
If you find any, give them a hard blast of water from your hose. That should largely take care of them, but you may have to repeat this a few times. It’s a good idea to give your susceptible plants a weekly shower to prevent them from taking hold.
Watch for Heat Stress
Soaring temperatures and high UV index can scorch plants, especially newly planted ones that haven’t had time to adapt. If you have plants that are turning yellow, brown, or white, they might be getting too much sun.
The only remedy is to give them some shade. (You can’t outwater sun scald, although many gardeners try.) If a sun-damaged plant is in a pot, move it to a shady area such as under a patio roof or tree.
However, if you are trying to shade plants in the ground, it’s not quite as convenient. Use whatever you have on hand and don’t worry too much about how your shade setup looks since it will be temporary.
I’ve used patio umbrellas, old lace curtains, patio chairs, laundry baskets, and many other inelegant solutions to give a plant shade in a pinch.
Upcoming Gardening Events in June
While the number of classes is tapering off in June, there are still numerous gardening classes to attend, many of which are online.
If you live in Tucson, be sure to check out these ongoing evening events now through August. (You may have similar festivities near you.)
- Tohono Chul’s “Chillin’ at the Chul”
- Arizona-Sonora Desert Museum’s “Cool Summer Nights”
- Tucson Botanical Garden’s “$5 Fridays”
You’ll find a comprehensive list of nurseries, botanical gardens, and organizations that hold classes, events, and sales in our Tucson Gardening Event Guide.
Don’t live in Tucson? Look for online classes. You can participate in these no matter where you live.
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for over 15 years.
