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. Here it’s June, a month that’s uniquely hard on plants and wildlife. It’s the hottest month of the year, and we often haven’t had significant rainfall for months, so your 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.
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.
The 10 hottest days in Tucson have all occurred between mid and late June and there’s every reason to believe this trend will continue.
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 taunted 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.
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.
Don’t be disappointed if your plants don’t look their best or flower abundantly. (I don’t look my best on a blazing hot, windy day either!) They’re putting their energy into surviving.
Here’s a snapshot of the activities you can do this month and those you should stop doing.
| ☑️ | Water deeply |
| ☑️ | Watch for heat stress |
| ☑️ | Watch for pests |
| ☑️ | Plant summer annuals |
| ☑️ | Sow wildflower seeds |
| ✖️ | Don’t plant |
| ✖️ | Don’t prune |
| ✖️ | Don’t fertilize |
Read on for all the details and exceptions!
What You Can 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, 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 summer yet, do it now. June might be spring elsewhere, but not in the desert. If you look at various watering charts, you’ll find that summer is considered “May through September.”
As we’re facing the hottest time of year, it’s critical that you’re watering 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 how to water your plants in June,
check out these articles:
How & Why to “Deep Water” Desert Plants
7 Tips for Watering Landscape Cactus
How to Water Desert Trees: How Often? How Much?
How to Water Desert Shrubs: How Often? How Much?
Most potted annuals need watering daily. If you are 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 people go out of town — ask me how I know this. 🙄
Before the monsoon is an excellent time to think about harvesting rainwater. It doesn’t need to be anything fancy — simply collect rain in whatever you have around that will hold water.
I have a rain barrel connected to a downspout, but I still set 5-gallon buckets around my roofline — you can never have too much rain water. Then I cover them with snap-on lids to keep out mosquitoes.
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, tree, or shade sail.
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.
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.
The exceptions are citrus, palm trees, and plants in containers. Palms can be fertilized in the summer. Potted plants benefit from a dilute solution of fertilizer every two weeks throughout the summer.
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.
| Lemons, Limes | Oranges, Grapefruit | |
| 1st | Jan. – Feb. | Jan. – Feb. |
| 2nd | March – April | March – April |
| 3rd | Aug. – Sept. | May – June |
Watch for Citrus “June Drop”
While we’re on the subject if 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
Other than removing any damaged branches from trees and shrubs, don’t prune. Pruning further stresses your plants by exposing new areas to sun and stimulating new growth.
There are a few light trimming tasks you can do now.
If you have citrus trees that are sending up suckers, go ahead and remove them now.
If you have palm trees, you can remove fronds that are completely dead but you don’t have to. Dead fronds shade the trunk and help keep the ground cooler. Don’t prune half-dead looking fronds which are still photosynthesizing enough to provide the plant with needed energy.
If you have yucca, agave, or hesperaloe that have bloomed, you can remove spent flower stalks after they’ve dried. If possible, leave them on while flowering, as they are important for pollinators.
Deadheading flowers is optional, but it does encourage new flowers, especially in potted plants.
You can give your lantana a minor trim now to encourage flowering throughout the summer.
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 nibbling on your plants in June. Now that desert 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.
Leafcutter bees, which usually make their first appearance in May, may continue to cut circles on the leaves of some of your plants, especially roses, redbuds, and bougainvillea.
They are important pollinators that use these circles to wrap their larvae. Please don’t spray, harm, or otherwise discourage them, they will be done shortly.
Upcoming Gardening Events in June
While the number of outdoor garden events is tapering off in June, there are still numerous gardening classes to attend, many of which are online. There is always something new to learn about gardening!
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 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 15 years.
Photo Credits
Bureau of Land Management (BLM) Arizona, Public domain, Wikimedia Commons
“Megachile Centuncularis” by JRxpo is licensed under CC BY 2.0
Mokkie, CC BY-SA 3.0, via Wikimedia Commons