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Desert Bounty

Successfully grow fruit trees in the arid Southwest.

By Nancy Erdmann

While there are many benefits to having fruit trees in your garden, being able to enjoy the tasty harvests is about as good as it gets. There are a variety of species that thrive in the Valley’s hot, dry climate, from tangelos, apples and limes to apricots, oranges and berries. Aside from their natural abundance, fruit trees also attract birds, bees and butterflies; offer shade during the summer; and produce fragrant blossoms that beautify any yard. Sounds like a win-win situation no matter how you look at it. Here’s how to get started.

SELECTING THE RIGHT TREES

For optimum fruit production in the low desert, experts at the Maricopa County Cooperative Extension recommend choosing deciduous tree varieties that have low-chilling requirements, bear early-maturing fruit and self-pollinate.

Chill hours are the amount of cold weather needed for a tree to set fruit. Maricopa County has 300 to 400 chill hours annually, so selecting varieties with 250 or so chilling hours should provide a solid crop each year once the plants are established. Be sure to select trees with fruit that ripens before the heat of summer arrives so that your produce doesn’t burn. Also, many species require cross-pollination in order to set fruit, making it imperative that you have two of the same type of tree (and in some cases, one of each gender) in your yard in order to yield an adequate crop.

WHEN AND WHERE TO PLANT

“The ideal time to plant depends on the type of tree and if it is potted or bare root,” says grower Duane Hebert, co-owner of Edge of Nowhere Farm in Whittman. “Potted trees can go in the ground October through March, while bare-root trees are typically planted in January and February.” For information about each, see “Bare Root vs. Potted” below.

When deciding where in the landscape to place your tree, your best bet is to find a spot with an eastern exposure, as it provides afternoon shade, says urban permaculture designer and owner of The Urban Farm in Phoenix, Greg Peterson. Avoid growing fruit trees in a hot microclimate, especially those with a western exposure unless there is some form of late-day shade. “I tell people to go stand for 15 minutes on an August afternoon in an area where they want to plant and see if they would want to live there,” Peterson jokes.

No matter where in the yard you grow your fruit tree, whether in bare dirt or grass, be sure to dig a basin around the plant and fill it with woody mulch. “This buffers the tree from the lawn’s watering schedule, builds healthy soil around its base and, if it’s planted in the lawn, allows it to get established before Bermuda grass can do any damage by using up all the soil’s nutrients,” Peterson explains.

IT’S ALL IN THE SOIL

“The single biggest thing you can do to successfully grow anything in the desert is to have healthy soil,” Peterson continues. “If you plant a tree in our native dirt, which contains less than 1% organic matter, it’s probably going to die.”

Healthy soil creates a layer of insulation by holding in moisture and keeping the ground cooler in summer and warmer in winter. “There are five components to healthy soil: dirt, air space, water, organic matter and the microoganisms that live in it. Dirt is simply broken-down rock that is highly compacted, making it almost impossible to grow anything in it. The good news is that all you need to do is add lots of organic matter to it,” the plant expert remarks. He recommends augmenting native earth with a good soil mix you can find at a local nursery.

“If you are going to spend 40% of your garden budget on a tree, expect to spend at least that much on supplements and soil,” he remarks. “If someone plants a tree in dirt with gravel, the tree likely won’t make it and their investment will be lost.”

Bare root vs. potted

Trees are sold either in containers or as bare roots. Bare-root trees come with their roots wrapped in bags often filled with moist wood shavings or sawdust and are less expensive than pot-grown trees. According to Cornell University Department of Horticulture, a bare-root tree contains 200% more roots than the same tree sold balled and boxed. Local nurseries often have a larger selection of bare-root trees and they are easier to handle due to their light weight. Bare-root plants also experience less transplant shock and start establishing themselves more quickly than containerized ones.

The downside is that while potted trees can be found year-round, bare-root varieties are only available for a limited time, usually November through March. In addition, sometimes trees in pots can start bearing fruit a year or two sooner than bare root.

PLANTING BASICS

1 Dig a square—not round—hole that is at least one-and-a-half times the size of the pot. A good place to start is by digging 12 inches deep and 2 feet out, which also works for a bare-root tree. Because much of the desert’s native soil is caliche, a hard layer of dirt that is almost impossible to penetrate, planting in a circular opening forces roots to hit the sides of the hole and continue in circles, essentially root-bounding themselves. In a square hole, when roots hit a corner, they won’t make a 90-degree turn but will instead continue growing straight into the native soil. It’s also a good idea to cut divots into the sides of the hole, so that the surface is not smooth and the roots have a place in which to grow.

2 Place 40% of the displaced native soil into a wheelbarrow. This dirt contains necessary minerals and will be returned to the hole when the tree is planted.

3 Toss aside the remaining 60% of native soil and substitute it in the wheelbarrow with a good planting mix consisting mostly of compost; pine bark; perlite, a naturally occurring mineral glass often found in commercial potting blends and presents like small, white Styrofoam balls; and cocopete, a growing medium made of coconut husks. This mixture introduces microbes that are able to help harvest the minerals out of the native dirt and make it bio-available to plants.

4 Add 2 pounds of Azomite, 2 pounds of worm castings and 2 ounces of mycorrhizal fungi to the mix in the wheelbarrow. These supplements can be purchased online or found at local nurseries, and at hardware, feed and livestock stores.

5 Stir up the soil mixture. Add a shovelful to the bottom of your planting hole, and place the tree in the pit with the graft point (where it’s attached to the rootstock) 3 to 5 inches above the soil. (See Urban Farm’s how-to-plant charts online at phgmag.com.) Fill in the rest of the hole with the mix from the wheelbarrow, making sure to cover the root flair (visible roots).

6 Top with mulch. Peterson observes the 6-6 rule: 6 inches of woody mulch placed in a 6-foot diameter circle around the base of the tree. He follows up with an additional 6 inches of woody mulch once or twice a year. “When the interspace between the dirt and woody mulch breaks down, it makes incredible soil. We are essentially mimicking the process that happens in a forest,” he explains. Within a few years, the dirt turns into a dark, deep, nice soil.” Water thoroughly to a depth of 3 feet.

7 Consider planting cover crops, such as sweet potato vines or cowpeas, around the tree’s base to shade it during the hot summer months, help build healthy soil and collect nutrients that can be used by the tree. Cover crops love the heat and can be on the same watering schedule as a fruit tree.

WATERING

“People think trees need to be watered every day, but they don’t. Too much water and the roots rot; not enough and the roots dry out. Either way, the damage looks the same,” Peterson says. “My experience with all of the fruit trees I’ve ever planted is once you get them past the first year and they are established, water once a month in winter and twice a month in summer.”

Trees need to be deep-watered throughout their entire basin to a depth of 3 feet. A soil probe or water meter can help you determine if you’ve penetrated the soil enough. “If you have a bubbler in the basin, set it to run three to four hours each time and completely fill the basin. If you have drip irrigation, a good solution is to buy a drip ring with emitters set in a circle that plugs into your drip system.” Do not, however, use chlorinated water, as it will kill essential microorganisms.

FERTILIZING

Fruit trees should be fertilized at regular intervals. “For newly planted trees, we use a light fertilizer, preferably fish emulsion with vitamin B,” Hebert says. The rest of the year—typically in February, May and September—use time-release (pelletized) fertilizers. “I like to think of the holidays that surround that as a reminder—Valentine’s Day, Memorial Day and Labor Day,” he adds.  You can also use a liquid fertilizer instead of pelletized. If you do this, you may need to feed monthly just before and during the growing season, which is between late February and October or November.

Visit phgmag.com to read Urban Farm’s Fruit Tree Nutrition Schedule for additional tips.

WHEN TO EXPECT FRUIT

“The classic question is, ‘How long before I get food from my tree?’” Peterson says. “Usually it takes about three years.” He suggests taking off all of the fruit in the first year if anything shows up and before it starts to take shape. “What we’re trying to do is get the tree to establish roots, not make fruit,” he explains. “Year two, remove most of the fruit so that by year three you have a good root system established and the tree is producing regularly. It goes something like this: no fruit the first and second years, a few pieces the third year, exponentially more the fourth year, and by the fifth year, oh my God!”

HARVESTING TIPS

Peterson advises that soft flesh fruits, such as apples, apricots, berries, grapes, peaches and plums, should be harvested by the beginning of July, otherwise they have a tendency to “cook” on the trees. “With stone fruit, I have never had luck with anything that ripens after July, and I have experimented with a lot of varieties,” he notes.

“Apples are a bit different as they are a little more resilient, but the trees I have seen that actually produce fruit and make it through the summer only yield a few apples,” he continues. “Anna and Dorset Golden apples, which ripen in June, yield hundreds of incredible fruits.” Citrus should be harvested November through March.

As far as the method goes, everything can be handpicked. The big issue, Hebert warns, is protecting softer-skinned fruits from pests, especially birds. “For peaches and apricots, we place bird netting over the entire tree. For figs, we prefer using organza bags on each fruit,” he notes.

“Mulberries can create a free-for-all between you and the birds when the fruit matures, as the trees grow too fast for bird netting and the fruit is too small to put bags on each of them. We sometimes pull the berries when they’re a little under ripe, but usually there still is some fruit to be found on the tree each morning and evening,” Hebert adds. “Apples and peaches will ripen on the kitchen counter, so you can extend the harvest by pulling some fruit while it’s still a bit unripe. On the other hand, figs need to be eaten within a day or two of harvesting, as they will go from ripe to rotten quickly.”

Tips for growing citrus

Fall is the best time to plant citrus in the low desert, says Kelly Saxer, lead farmer at Agritopia Farm in Gilbert. “Fall planting allows young trees to have a longer span of moderate temperatures to get established before the summer heat hits,” she explains. Generally, sour orange is the rootstock that does best in the low desert. “If you purchase your citrus trees from a reputable nursery in the Valley, this should be the rootstock your tree is grafted on.”

Citrus fruit usually start to ripen in late November to early December, but some varieties, such as Valencia oranges, oroblanco grapefruit and Minneola tangelos, can mature as late as January or even February. Fruit should be cut from the tree versus pulling it from the branch, which can damage the limbs. “Be sure to harvest all of the fruit no later than March, as this will prevent it from dropping, which can encourage a rodent problem,” Saxer notes.

Citrus trees do best with deep, infrequent waterings and prefer drying out between irrigations. “Citrus should be fertilized at regular intervals throughout the year,” Saxer adds. “At Agritopia, we fertilize every three months by spreading composted chicken manure around the base of the trees.”

Why Rootstocks Matter

Most deciduous fruit trees are grafted onto rootstocks, which are the base or underground portions of related species that already have established, healthy root systems. According to the Maricopa County Cooperative Extension, this provides resistance to disease; improves performance in certain soils; increases tolerance to drought and salt; controls a tree’s growth rate and size at maturity; and alters fruit taste, texture, size and yield.

“Rootstocks are critical when it comes to tree selection, as they will determine both the size and virility of the tree itself,” notes grower Duane Hebert. “Without the right rootstock, the tree is going to struggle in our soil.” Most local nurseries offer fruit trees that are grafted onto rootstocks that thrive in the Sonoran Desert.

What is a stone fruit?

A stone fruit has a large pit (or stone) in its center surrounded by a soft, juicy flesh with thin skin. Examples include dates, mangoes, nectarines, olives, peaches and plums. Surprisingly, raspberries, blackberries and mulberries are also considered stone fruits in that each berry consists of a cluster of tiny stone fruits with pits. Unlike other fruits, stone varieties generally stop maturing once they are harvested, making them seasonal. The best way to tell if they’re ripe is by smelling them. The more aromatic the better. A little bit of bruising on the skin is also a good indicator of ripeness.

Recommended Varieties for the Low Desert

APPLES: Anna, Golden Dorsett, Ein Shemer, Tropic Sweet (harvest in late May through June)

APRICOTS AND APRICOT HYBRIDS: Katy, Gold Kist, Flavor Delight Aprium (harvest May through June)

BLACKBERRIES: Triple Crown, Black Satin (harvest May through June)

BOYSENBERRY: Thornless (harvest May through June)

CITRUS: Arizona Sweet and Valencia oranges for juicing (includes Trovita and Macetera); navel oranges for eating (Robertson, Cara Cara, Washington); Bearss limes; Improved Meyer lemon and Lisbon lemon; Daisy and Honey mandarins; Blush and oroblanco grapefruits; Minneola tangelos; Fairchild tangerines (harvest most October through April)

FIGS: Black Mission, Brown Turkey, Panache, Black Jack, Peters Honey, Desert King, Janice, Violette de Bordeaux (most will ripen in late June/early July and again in late October/November)

GRAPES: Thompson seedless, Flame (harvest May through June)

MULBERRIES: Pakistan, Shangri-La, Illinois Everbearing, Persian (harvest April through July)

OLIVES: Koroniki, Manzanillo (harvest in November)

PEACHES: Florida Prince, Early Amber, Earligrande, Desert Gold, Tropic Snow, Mid Pride, May Pride, Eva’s Pride (harvest May through June)

PLUMS: Santa Rosa, Methley, Beauty (harvest May through June)

POMEGRANATES: Parfianca, Eversweet, Wonderful, Cranberry, Desertini, Arianna (harvest October through November)

RASPBERRY: Baba Red (harvest May through June)

For a more extensive list of fruit tree varieties, their attributes and when to plant and harvest, download “Deciduous Fruit and Nuts for the Low Desert” at extension.arizona.edu.

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