Monsoon rains have evaporated, followed by drier air and cooler nights. Summer's heat has broken at last. Welcome fall!
Summer leaves plenty of flowers in its wake. You don't need to deadhead at this point in the season. Allow plants to set seeds and fruit for wildlife.
Take note of what's blooming now to find plants that can fill in holes in your garden's seasonal color scheme.
Roses make a comeback this month, filling the air with fragrance. Don't worry about deadheading bushes now. Let blossoms ripen to form hips for winter interest.
Traditional fall favorites are still going strong: asters, garden mums, goldenrod, zinnias, and the last of the dahlias.
Ornamental grasses send up flowering shoots this month. Discover some of the season's most beautiful grasses: pink muhly grass (Muhlenbergia capillaris) and cream-color deergrass (Muhlenbergia rigens).
Other plants in flower include globe mallow (Sphaeralcea ambigua), milkweed (Asclepias spp.), Tecoma hybrids, and cascalote tree (Caesalpinia cacalaco).
Test Garden Tip: Invest in a frost blanket to extend the growing season for cutting gardens filled with annuals. Frost blankets, which are made from spun polyester or plastic, can be anchored in place for weeks. The fabric allows water and light to penetrate, but not frost.
Fall is the ideal time to plant. Soil temperatures remain warm from summer's heat, and cooler air eliminates the need for incessant watering. Plants can settle in before winter cold arrives, developing root systems that will give plants a jump start come spring. What should you be planting?
Hardy, container-grown trees and shrubs. Choices include common lilac (Syringa vulgaris) or Asian hybrids (S. x hyacinthiflora), and redtwig dogwood (Cornus alba). Also plant summer-dormant trees: Joshua trees (Yucca brevifolia), Baja senna (Senna purpusii), and boojum tree (Fouquieria columnaris).
Cool-season annuals, such as pansy, Calendula, snapdragon, dianthus, and stock. These plants will flower all winter. Also add flowering cabbage or kale for strong winter color.
Seeds that should freeze, including larkspur, poppy, forget-me-not, and gloriosa daisies. These plants will unfurl flowers next spring.
Test Garden Tip: Avoid planting tropicals in all but the warmest parts of the region. These plants do better when added to the landscape in spring. The list includes palms, oleander, bird of paradise, ginger, citrus, and avocado.
Pick all green tomatoes before a hard frost. Tomatoes stop ripening when temperatures remain below 50 degrees F. Ripen tomatoes indoors, which can take from two weeks (at 70 degrees F) to four weeks (at 55 degrees F).
Harvest pumpkins and winter squash before any frost settles on them. Cut stems to leave a 1- to 2-inch-long portion attached to fruits. If you intend to store the harvest over winter, cure fruits first by sitting them in the sun for 10 days. Place fruits in a protected spot at night if frost threatens.
Plant salad greens -- leaf lettuces, spinach, mustard greens, radishes -- for a late crop. With frost blankets, extend the harvest season about a month.
Plant garlic in fertile, well-drained soil. At higher elevations, where winter is more severe, bury individual cloves 3-4 inches deep. Where winter is mild, bury just 1-2 inches deep. Choose largest cloves for sowing; eat smaller ones.
As edible crops finish, pull vines and rake fallen leaves. Gather any fallen fruit. Don't compost leaves or fruit with disease issues. Cleaning up the garden before winter is a good practice to help defeat pests and diseases.
Bulbs. Prechill bulbs for spring blooms, including tulip, hyacinth, and crocus. Purchase daffodil, grape hyacinth, anemone, and Ranunculus. Hold for planting next month. Store in a cool, dry place.
Watering. Reduce watering to help plants harden off for winter. Do this gradually so plants can adjust. Be sure to reduce both watering frequency and duration. Likewise, adjust irrigation timers to reflect your fall watering reduction scheme. Generally, you should program timers to come on later in the day. And in the coldest areas of this region, winterize irrigation systems by midmonth.
Fertilizer. Don't fertilize landscape plants after October 31, except for cool-season turfgrasses.
Pruning. Cut peonies and other perennials to 3 inches; throw away diseased foliage to prevent spread of disease in your compost.
Test Garden Tip: Take a moment to update your garden journal, jotting notes of things that worked well this season and what failed. Be sure to record which vegetables were planted where so you can rotate crops next year.
Take advantage of fall's cooler weather to tend to labor-intensive chores.
Dig and Divide Perennials: Dig and divide established perennials. Plants that need dividing include those that may have stopped flowering due to being overcrowded, those that may have outgrown their spot in your garden, those that may have developed a dead area in the center of the clump, or those you want to use to share some starts with a friend. Keep newly planted divisions of your perennials well-watered. Consider adding a high-phosphate fertilizer to give new root formation a boost.
Dig and Lift Bulbs: After frost nips foliage late in the month, lift bulbs of canna, calla, dahlia, tuberous begonia, and gladiolus if they're not hardy in your part of the Southwest. Allow bulbs to dry in the sun for several days, then store in peat moss or sawdust in a cool, dry place for winter. In warmest regions, these tender bulbs don't have to be lifted. Simply cut back dead foliage and mulch plants well for winter.