Desert Gardening Fundamentals
Gardening Tempe Style
Fundamental Rules for Gardening in the Desert
Disregard any preconceived notions about gardening.
The seasons are reversed in Tempe; plant in the fall, enjoy the winter, harvest in the spring and go indoors for the summer.
Learn to love new plants as well as keeping a few favorites.
Roses, mums, geraniums and irises will thrive; but leave old favorites to like peonies, tulips and hydrangeas in the greenhouse. Going to the Desert Botanical Garden will introduce you to desert plants like penstemons, aloes, fairy dusters and orange firecrackers.
Remember desert soil not only looks different, it is different.
You will get used to its brown color. It lacks organic matter and has a high salt content. Because the need to add organic matter ranks high, learn composting. Forget about adding lime, since the soil is alkaline.
Get acquainted with the office of your county agent for up-to-date information.
The Maricopa County Extension office is located at 4341 E. Broadway, Phoenix. The agent has tapes, pamphlets and other resources covering almost every aspect of Arizona gardening. Phone: 602.470.8086
To save water, xeriscaping can be an alternative to a lawn. Consult the water bill for information on the next course in desert-friendly landscaping.
January -- The Bare Facts
Roses: Of all eastern and mid-western long time favorites, roses do surprisingly well in our climate. Find out from the local nurseries which roses grow best here. At the nursery, select bare root plants having plump, sturdy canes and undamaged roots, which have not yet leafed out. Soak entire plant in water and Superthrive over night. Dig a big hole (18 inches square), mixing in lots of humus and a handful of high phosphate fertilizer (high middle number). Spread roots out, set so that bud union is above surface level, fill dirt and water well.
Trees and Shrubs: Prune deciduous trees and shrubs (not evergreens like bougainvillea). Prune established roses and cut back Mexican bird of paradise to one foot.
Lawns: Dormant lawns need once-a-month watering. Fertilize winter lawns every four to six weeks.
Flowers: Continue setting out bedding plants and hurry to plant in the last of the bulbs. Transplant carnations, chrysanthemums and violets. Fertilize fall-planted annuals with high phosphate fertilizer.
Vegetables: Plant artichokes and asparagus. Feed fall-planted vegetables and sow more radishes and lettuce.
Weather Wisdom: If frost threatens, water everything well, except for cactus and other succulents Check on outside temperatures to track how your home micro-climate compares with the temperatures forecast and reported. Cover tender plants with sheets or light cloths. Tomato cages make a good framework to hold them.
February-March ~ Scent of Spring
Shade Trees: Where you place a tree is important for shade control. Also consider its eventual size, for in this climate plants grow fast. Deciduous trees like honey mesquite, velvet ash and honey locust might be good choices for southern exposures while tall evergreens might get the nod for the north side.
Citrus Trees: A good time to plant citrus with grapefruit and kumquats being least frost tender. Lemons and limes don't take kindly to cold. Remember one lemon tree can supply a neighborhood. Citrus need to be fertilized three times a year: late January to early March before blooming, in May after small fruit appear, and in early August. Use a high nitrogen complete fertilizer. Water every 7-14 days in summer but lengthen watering schedule to 4-8 weeks in winter.
Deciduous Fruit Trees: If you want fruit as well as shade, these trees provide summer shade and allow the sun to visit in winter. Selections could include apple, apricot, plum, peach or figs.
Flowers: Divide chrysanthemums and start new cuttings. Pick dead blooms from spent bulbs, leaving the foliage to provide food for next year. Let African daisies go to seed to bloom another spring. If you missed the fall planting, it is not too late to set out the following bedding plants:
Annuals: petunias, alyssum, pansies, statice, delphiniums, calendulas, snapdragons, stock, dusty miller and decorative kale.
Perennials:marguerites, coreopsis, dianthus, gaillardias, geraniums, hollyhocks, sweet William, Shasta daisies.
Lawns: Even if you are xeriscaping your yard, some areas of turf grass can be a welcome as an oasis near the home or a play or recreation area. Consider Tifgreen as turf grass. If you have overseeded with a winter lawn, water rye grass weekly. Water dormant Bermuda every three weeks.
Vegetables: Nothing is better than home grown, so think about planting cantaloupe, squash, sweet corn, chard, leaf lettuce, peppers, onion sets and beans in prepared beds. If you want tomatoes, they should be in the ground but be ready to provide frost protection.
Fertilize: After their winter fast, a complete fertilization of trees, plants and non-overseeded lawns should be on the agenda except for frost damaged plants. Before planting your spring vegetable garden apply a complete fertilizer. Roses seem especially hungry, so begin a monthly fertilizing program for them now through October. Oregano Super Rose food is a good choice.
Birds: Watch for migrating warblers and goldfinches, who time their arrival for the dandelion harvest.
April-May ~ What Blooming Months
Trees, Shrubs and Vines: Plant container grown or balled and burlapped trees. After frost danger is past, plant bougainvillea, which thrives without much water or fertilizer Other tender evergreens such as Queen's wreath (coral vine) and sprengerii should go in the ground Citrus: Finish planting and deep water every two weeks except when trees are blooming as too much water causes blossoms to drop. Olive: To prevent fruit from setting, apply a fruit control hormone when the small white flowers appear.
Flowers: Mulch roses before summer heat with 3-4 inches of forest mulch. Bedding plants that have the best chance of surviving summer heat are marigolds, periwinkle, kalanchoe, portulaca, vinca, zinnias, lisianthus and lavender. Mexican primrose is a hardy perennial ground cover with pink flowers that is a real sun lover. It is also very invasive, so plant in a bed by itself. When transplanting seedlings, select a cloudy day or late in the afternoon. Carefully loosen soil around plant roots, place in prepared soil and tamp soil firmly around plant; water deeply with B12 solution. Protect from the sun the first few days in the ground.
Lawns: Begin cutting overseeded winter lawns short to allow sunlight to encourage growth of Bermuda. For Bermuda lawns not overseeded, fertilize with ammonium sulphate when the green grass begins to grow. Every 4-6 weeks from May through October fertilize with 5 pounds of ammonium sulphate per 1,000 square feet. Brown spots in hybrid Bermuda (Tifgreen) indicates Pearly scale. Apply Oftanol in late May and repeat in 30 days.
Vegetables: If March temperatures didn't reach a consistent 75 degrees, which is the ideal veggie planting temperature, now would be the time to plant. Good choices are squash, sweet potatoes, okras, melons and corn. Soak okra seeds overnight. Warm weather affects pollen; hand pollinate squash, peppers and eggplant. Shake tomatoes in early morning. Patio variety tomatoes are ideal for container gardening.
Birds: Provide water for birds. Give hummingbirds a mixture of 5 parts water to 1 part sugar syrup (don't use honey) and keep feeders clean.
June-July-August ~ Plants Don't Vacation Even If You Do
General Rules for Summer: These months in Tempe are the reverse of the Saskatoon or Minneapolis gardener's experience. The gardener's goal is to keep things alive until the weather improves. These rules can apply throughout the hottest months:
- Water slowly and deeply to avoid salt buildup.
- Make basins for trees and shrubs with a brim or dike somewhat outside the drip line (edge of leaf canopy). Established trees may have roots five feet deep, shrubs to three feet deep, while annuals and vegetables could have roots a foot or more deep.
- A well-regulated watering system is worth every penny. The Desert Botanical Gardens provides a detailed watering guide.
Trees and Shrubs: A little fertilizer will replace minerals leached out by frequent watering. Lightly prune straggly pyracantha and bougainvillea. Spread planting area with two inches of mulch. Give citrus a third of their annual dose of fertilizer in August.
Vegetables: Some vegetables that do pretty well in the summer are peppers, chilies and eggplants.
Lawns: Mow lawns twice a week, cutting no more than 1/3 inch off the top. Place a few empty coffee cans at various places on your lawn to see how well you are watering.
Flowers: Roses and other perennials may show yellowing of leaves, indicating iron deficiency or chlorosis. Feed with chelated iron. Remove annuals and sickly vegetables. Covering the empty beds with black plastic for a couple of months will sterilize them; stopping the progress of nasty bugs and diseases. Turn beds over in August, adding lots of compost. Watch for sunburn and contrive some sport of shade. Mulch heavily. Make a note of relentlessly sunny places and avoid them next year. Cut back perennials (bottle bush and glove mallow).
Summer Color - Perennials: Aloes, anisincanthus, bougainvillea, brittlebush, desert marigold, fairy duster, hesperaloe, justicia, lantana, penstemon, plumbago, ruellia, Texas sage, queen's wreath and yucca Annuals: Vinca, sunflower, portulaca, linum and celosia
Pests and Problems: Borers may attack the stems of roses; always seal off a cut of pencil-size stem, nail polish will do. Red spiders make leaves look dusty and freckled with light spots. Give plants a blast of water with the hose or spray with kelthane. White flies have been extraordinarily pesky. Call county agent for latest remedy for them.
Birds: They are molding and out-of-sorts. Keep providing water and hummingbird juice.
September-October-November ~ Plant Now For Spring
Trees, Shrubs and Vines: Bougainvillea's not blooming? These arid region plants bloom best when roots dry completely between soakings.
Citrus: Wrap trunks of newly planted trees for the first few years from mid-November through February with palm fronds or burlap to protect from frost.
Desert trees: November is an ideal time to plant native and hardy non-native trees. Consider using water saving trees like Chilean mesquite, blue palo verde, sweet acacia, carob and desert willow.
Flowers: Late in September sow African daisies, calendulas, California poppies and nasturtiums. Soak nasturtium seeds overnight before planting. Don't fertilize mums after buds show color or appear. When weather cools off in mid-October it is time to buy some of these bedding plants: pansies (F1 hybrids best), stock, snapdragons, lobelia, Iceland poppies, dianthus, petunias, sweet alyssum. Plant when night temperatures drop to the 60s. Lightly prune and fertilize roses to encourage fall bloom. When daytime temperatures fall below 85 degrees, it is time to plant sweet pea seeds in well-prepared beds. Soak seeds overnight. It is frequently necessary to seed twice for good results.
Bearded Iris: Rhizomes should be in the ground by now if not planted in August. They like a high phosphorus diet. Rhizomes should not be planted deep. Place in a circle with toes pointing inward and cover with a small amount of soil.
Bulbs: Now is the time to bed them down. The general rule of thumb is to plant bulbs in a depth 3 to 4 times their thickness. Consult charts for planting depths if in doubt. In the planting bed, place some high phosphate fertilizer at base of each hole; cover fertilizer with soil and plant. Water completely on planting. Bulbs do not need too much water until first sign of leaves appear in spring. Suggested varieties: Dutch iris, ranunculus and daffodils. Alyssum is a good base for bulbs.
Wildflowers: Sow seeds as temperatures cool for a delightful spring show. Choices include lupin, gold poppy, owls clover and Parrys penstemon.
Herbs: Don't forget to plant a container near the kitchen. Rosemary, basil, parsley and chives will delight the cook.
Lawns: Feed Bermuda grass in September, if you don't plan to overseed with rye. From early to mid-October is the ideal time to overseed lawns.
Vegetables: As soil cools in late September to early October, plant those hardy vegetables that need to mature in cool weather. They include: beets, broccoli, cabbage, carrots, lettuce, onions, peas, radishes, spinach and turnips. For a head start, set out transplants when available.
Birds: Watch for the tourists to come flying in. a towhee or a grosbeak is a refreshing change from the finches and sparrows you've been watching.
December ~ Season's Greetings From Your Garden
Flowers: December is almost your last chance for bulbs. Don't be enticed by end of season sales. Tulips and hyacinths need several months of chilling in the refrigerator to bloom only once. The best bulbs for Tempe seem to be the narcissi bred for forcing like paper whites and Salerl d'Or. Others that do well are the corms: freesias, sparaxis and gladiolas. Long-lived reliable bloomers are grape hyacinths and Dutch irises.
Vegetables: Be sure to water. Light December rains usually produce insufficient moisture for anything but weeds. Prepare to protect tomatoes and peppers from frost. Among the herbs, basil is particularly tender.
Lawns: Apply pre-emergent herbicide to grass and gravel lawns to keep undesirables off your turf. Do not spray near areas you may have sown with wildflowers.
If you want more information, consider joining the Tempe Garden Club.