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August/September 2022 Garden Checklist and Solutions

Low Elevations

SQUASH, PUMPKINS AND GOURDS Transplant or directly sow seeds into the garden now through September for harvesting before first frost, usually around Nov. 24 in Tucson and Dec. 8 in Phoenix. Insect pests such as cucumber beetles, squash bugs and whiteflies love cucurbits and are active in late summer, so cover new plantings with floating row covers, available at most garden centers, until the first flowers appear. Uncover at that time to allow pollinators to visit and facilitate fruit production. Luffa and birdhouse gourds are fun to grow and make wonderful holiday gifts from the garden. Varieties of summer squash, such as patty pan, zucchini and yellow crookneck will yield within 60 days of planting. “Early Giant” is a jack-o’-lantern type of pumpkin that matures in 100 days.

PREPARE FOR FALL PLANTING Cull dead vegetables, annual flowers and herbs to make way for new installations in October. Shred dead plants with a sharp shovel and add to the compost heap. If you solarized this past summer with clear plastic, remove that now. Amend garden soil by mixing a 1-inch layer of composted manure into the top 4 inches to kickstart biological activity. Additional organic matter from composted yard waste should also be added at this time, up to 3 inches more, to improve soil water-holding capacity and available oxygen for healthy crop roots.

PRUNE STORM-DAMAGED TREES Use clean, sharp tools to remove limbs that were broken during monsoon storms. Make all cuts at the point of the stem’s attachment without leaving a stub or coming too close to the trunk. Download “Pruning Trees and Shrubs” at for more instructions on how to make a proper pruning cut.

Allow luffa gourds to dry on the vine until the skin has turned from green to brown, becomes brittle and begins to pull away from the fibers inside the gourd. The gourds will feel lightweight at this point, and you should hear seeds rattle inside when you shake them.

Break open the skin at the blossom end of the gourd (opposite the stem) to reach the seeds, which can be planted next year. Remove the rest of the brittle skin with your fingers to reveal the sponge beneath. Rinse under water to remove any sap and plant particles. Allow to dry, then cut to desired size using a sharp knife.

Low and Middle Elevations

SUNFLOWERS Support healthy bee populations by planting pollen- and nectar-rich flowering plants. Sow seeds of sunflowers now for autumn bloom. Make sure to select varieties that are labeled “open-pollinated.” Otherwise, they may not produce the pollen that bees need for food. ‘Valentine’ is a nice choice that reaches 5 feet tall and produces 4-inch, lemon-yellow flowers. ‘Florenza’ grows to just over 3 feet in height and produces brown, red and yellow flowers attractive to a number of pollinators, including honeybees, bumble bees and other native bee species.

Middle Elevations

COOL-SEASON VEGETABLES Once daytime temperatures remain below 100 degrees, direct seed, root, leaf and stem crops into garden soil. Chard, kale, spinach, leaf lettuce and mustard greens can be eaten as microgreens as soon as leaves are produced or left to grow and harvested continuously. For continuous harvest, only pick the outermost leaves, leaving inner leaves to protect the growing crown of the plant.

DIVIDE PERENNIALS Dig up clumps of spring-blooming perennials such as iris, daylily, coneflower, black-eyed Susan and hostas with a shovel. Once the root ball is detached from the ground, lift it up and shake loose soil from the clump and separate individual crowns, each with their own set of leaves and roots. You may need to cut thick roots with a knife if they do not divide easily by hand. Immediately place separated plants into their new location, or pot and share with friends and neighbors.

I live in the West Valley and am intrigued by a turf alternative called “dwarf carpet of stars” (Ruschia lineolata). It’s apparently hardy from 20 to 120 degrees, so it seems like a good fit here. It’s sold in Las Vegas and around Los Angeles, but I’m struggling to find any locally. Could that be because it’s a new-ish species for groundcover?

Ruschia lineolata, “carpet of stars” was previously known as Mesembryanthemum lineolatum, which may be more recognizable to some as a member of the ice plant family, Aizoaceae. Native to South Africa, ice plants have long been used to stabilize sandy slopes in California. Although carpet of stars has been gaining attention in Nevada and California, I, too, was unable to find any available locally in Arizona, but there are a number of online plant sellers that offer them. Try reaching out to your favorite independent nursery and ask them to order some for you; or try your luck having them shipped directly to your home. Hold off until October, after temperatures have cooled somewhat and planting conditions are more favorable. Ice plants thrive in sandy soil and do not tolerate clay, slow-draining soils that are common in our area.

Middle and High Elevations

TREES, SHRUBS AND PERENNIALS Search nurseries for native beauties such as kidneywood (Eysenhardtia orthocarpa), a small tree that attracts butterflies with sweet-smelling flowers, manzanita (Arctostaphylos spp.), a group of shrubs with dark, mahogany-colored bark or hummingbird mint (Agastache cana), a pink spring bloomer that hummingbirds love. Dig the planting hole twice as wide but no deeper than the root ball. Backfill with the excavated soil and settle with water. Cover with 3 to 4 inches of mulch to protect the roots and conserve moisture.

We bought a home with several mature rose bushes in the landscape. They bloomed for much of the summer but aren’t producing as many flowers now. Should we prune them?

To keep your roses blooming almost year-round, experts suggest constant “deadheading” or removing spent flowers to stimulate a fresh bunch. Make sure plants get regular, deep watering until November. September is a good time to apply a rose fertilizer; always follow the instructions on the product label. Applying too much can burn the roots. You can also lightly prune canes by removing about one-third of the length of the stems, but no more. Use clean, sharp bypass shears to cut canes at a 45-degree angle. Anvil-type shears crush stems and are better suited for cutting dead wood.

Illustration by Gary Hovland

My son discovered a huge, yellow, red and black bug eating a bee in our garden. Should we be concerned about it? 

It was probably an assassin bug your son saw eating the bee. Assassin bugs are predators that can sometimes be observed lurking around flowers, waiting for unsuspecting prey, including bees, to visit. They grab their prey and puncture it with their “beak” that pumps digestive enzymes into the body of their catch. The beak is then used to suck the now-dissolved internal tissues from their prey into their own gut. Although we don’t want to see bees unnecessarily killed, there is no evidence that any bee populations are under threat from assassin bug predation. Be careful around assassin bugs, they can use that beak to puncture human skin too, which can be quite painful, but not otherwise dangerous.

High Elevations

REDUCE IRRIGATION Help deciduous vines, shrubs and trees transition into dormancy by gradually reducing supplemental irrigation after Labor Day.

CONTINUE HARVESTING SUMMER CROPS Most vegetables do not need to ripen to taste good. In fact, they tend to have better texture and flavor when picked young and small. As radishes, beets, carrots and turnips grow larger and older, the sugars are converted into starch and lose their sweet flavor. Once leafy greens start to bolt (the stems elongate and flower stalks appear), the leaves usually become too bitter to eat. Summer squash, such as zucchini, becomes woody with age and is best picked within a few days of appearing on the plant.


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