The challenge with gardening in Arizona comes when temperatures soar in the hot, dry months of the summer. It is possible to have a productive garden in the summer heat. Here are the essentials to know for summer gardening in Arizona.
Plant Heat-Loving Varieties for Summer Gardening in Arizona
When summer gardening in Arizona, choosing the right vegetables and planting them at the correct time is a matter of life and death for the plants. Use the U of A Cooperative Extension Planting Calendar for Maricopa County. Select varieties that mature quickly. There are a few vegetables that survive and even thrive in our intense summers. Here are a few of my favorites:
Call them Snake or Asparagus beans but one thing is the same, they thrive in the heat and produce all summer long. In the low desert of Arizona, plant from March through the beginning of July. For more information about growing beans, read this post.
Looking for a summer spinach alternative? Try Malabar spinach, a heat-loving veggie that is not a true spinach, but rather an asian vine that is high in vitamins A and C. The leaves are delicious in salads, stir fries, and summer soups. Plant from March through May in the low desert, and harvest it all summer and fall.
Armenian cucumbers are a long, slender fruit in the melon family which taste like a cucumber and also look like a cucumber inside. These take the summer heat like a champ. I harvested baskets-full last year from just a few plants. In the low desert of Arizona, plant them from the end of February through the beginning of July. For more information about growing Armenian cucumbers read this post.
Sweet Potatoes grow best in hot weather, and have many times more beta carotene than carrots. Plant transplants or slips (not seeds) from the end of March through June in the low desert of Arizona, and the leaves will keep your garden green and beautiful all summer. Harvest sweet potatoes in late fall. Bonus: the leaves are edible and delicious!
Provide Shade for Summer Gardening in Arizona
The sun’s intense rays in the hottest months of the year are too much for most plants. Shade cloth, sunflowers, and vining plants can all be used to provide shade for tomatoes, bell peppers, newly-planted plants, and other plants that prefer shade when summer gardening in Arizona.
Shade Cloth for Summer Gardening in Arizona
If your garden area is in full sun, consider adding shade cloth. Don’t think of completely enclosing the garden, but rather providing some relief when the sun is at its highest. The area should receive some sun throughout the day. For example, attach shade cloth to existing trellises with zip ties. At the end of the season I remove the zip ties, roll the shade cloth up, and store it away. When the summer heat comes again, I re-attach it with new zip ties.
Sunflowers Can Shade Arizona Summer Gardens
Add sunflowers around your garden to provide shade. Sunflowers are one of the easiest plants to grow from seed. Sunflowers grow quickly and depending on the variety can offer shade to surrounding plants. Once grown in a garden, they often reseed and pop up year after year. At the end of the season, cut off the stem at the base of the dirt rather than pulling out the entire root system. The remaining root will decompose and add organic matter to the area. Sunflowers can be planted in the low desert from February through July.
Vining Plants Can Shade Arizona Summer Gardens
Consider planting sun-loving vining vegetables (Armenian cucumbers, luffa, malabar spinach, etc.) purposely to provide shade for other plants that don’t tolerate full sun. Notice areas in your garden that could utilize plants as shade. Vining vegetables can be grown over artichoke crowns that go dormant during our hot summers to protect them from intense heat that might damage the crowns.
Water Arizona Summer Gardens Correctly
Watering summer gardens in Arizona is the most important care you can give your plants. Problems in the garden are often traced back to watering issues. The best way to determine how much you should water is observation of your plants and soil. There is no set time for everyone to water because there are so many factors involved (sun, shade, air temp, microclimate, age and size of plant, etc.).
Principles to consider when watering:
- Water deep enough to moisten plant’s root system and prevent salt burn. Salt builds up in soil where watering level ends. It is a good idea to occasionally water deeply to flush the salts out of the root zone and soil. Use a soil probe (any kind of long metal object such as a long screwdriver) in the morning to check watering depth. If the probe moves easily through soil, it is moist. If not, the soil is dry. Or check with a moisture meter. Let the top inch of soil dry out before you water again.
- Water wide enough to encourage root development and growth.
- Monitor plants for signs of underwatering stress (leaf curl, wilted or dropped leaves, branch die back) to help you determine how often to water. Plants require more water when it is dry, windy, and in the summer heat. Plants that wilt in the afternoon but recover by morning are suffering heat stress, not water stress. Take care adding more moisture so as not to cause root rot. Check soil for moisture before watering. Allow plants to develop some heat tolerance by not overwatering.
- Water the soil not the plant. Because of the salt content in our water, avoid putting water on the leaves. Wet leaves can also encourage and spread disease. Drip systems are effective for this.
- Water in the morning. Plants absorb moisture more effectively in the morning. It prepares plants before the heat of the day. Morning waterings also help prevent waterborne diseases and pests that can occur if you water at night.
6. Some type of automatic watering system is best. Automatic watering can be simple, such as a battery-operated timer connected to your hose bib, with either a soaker hose or drip line going to the garden. Try to be in the garden when the system is on so you can be aware of any issues (leaks, dead battery in timer, etc.).
7. Consider adding ollas to the garden for extra thirsty plants (tomatoes, squash, etc.) rather than running your irrigation system an extra time or watering by hand (which can get water on leaves).
Ollas are a form of plant irrigation that provide water slowly at the roots as the water seeps out the terra cotta pot that is buried underground. You refill the olla as it empties.
Mulching Summer Gardens in Arizona
Mulch, Mulch, Mulch when summer gardening in Arizona. Use compost, pine needles, or straw around your plants. Here are a few of the many reasons to mulch:
- Insulates the soil and keeps the temperatures more even.
- Mulching slows evaporation, allowing plants access to more water.
- Mulching keeps the soil from developing a hard crust that is difficult for irrigation to soak into.
- Weeds are less likely to sprout. When you mulch, your plants won’t compete with weeds for water and nutrients.
- As mulch decomposes it adds organic matter and nutrients into the soil.
Adjust Expectations for Summer Gardening in Arizona
- Understand your garden will probably not look its best in the heat of the summer.
- Be aware that pollen in pepper and tomato plants may not be viable when temperatures are over 100 degrees. Fruit that is set will continue to mature, but new fruit may not be produced.
- With intense heat, long days, and nights that don’t cool off, many plants go into summer dormancy. They focus on staying alive rather than growing.
- This is not the time to prune, trim or over-fertilize.
- Stressed plants are more prone to pests and diseases. Monitor plants and consider pulling them if they become overwhelmed so the rest of the garden is not infected.
- During the monsoon season and more humid months of July and August, plants may come out of dormancy.
Consider Taking the Summer off when Gardening in Arizona
Summer gardening in Arizona is challenging. If you travel frequently, don’t like the planting options, or would rather not spend extra time outdoors during the hottest time of the year, here are some alternatives:
- Let the garden rest. Continue to provide some irrigation so that all life in your soil doesn’t die, but let garden beds rest. We often garden year round in Arizona – use this time to take a break and plan your fall garden!
- Feed the soil with a cover crop. Ideas for a cover crop in the summer are soybeans, alfalfa or buckwheat. Plant crop and allow to grow until just before flowering. At this point, turn the crops into the soil — after about 3 weeks your soil will be ready for planting. The stored nitrogen in the roots and leaves will remain in the soil and, along with the added organic matter, helps prepare your soil for next season’s plantings. Benefits of growing a cover crop include: weed reduction, improved soil drainage, boosted beneficial insect and soil microbes, added organic matter and erosion prevention.
- “Solarize” your soil. If you have weed issues, diseases, or nematodes in your soil, consider solarizing it. Solarizing the soil takes advantage of the sun’s heat to kill the weed seeds, diseases, or nematodes lurking in the soil.
A Basic Overview of Solarizing:
- Add manure into the soil & water well.
- Cover with clear heavy plastic sheeting.
- Bury the edges of the plastic, or hold down with rocks.
- Allow soil to “bake” in the sun for at least 6 weeks.
- For more information about how to solarize soil, read this article from the Arizona Cooperative Extension office.