FIMBY: Why winter is the perfect time to plant fruit trees

According to UC research, almonds, figs, and olives—native to the Mediterranean—are the most drought-tolerant fruit trees. Pineapple guava, a low-water shrub, offers tropical flavor and silvery leaves. Pomegranates, another Mediterranean native, produce bright orange blooms and ruby red fruit while needing only twice-monthly irrigation.

But the water-wise fruit list doesn’t end there. Apples, apricots, cherries, pears and prunes are mostly drought-resistant. Nectarines, peaches, and citrus need more consistent watering, but can flourish in a water-wise garden once established.

Fruit trees are ideally suited to our dry-summer climate, observes longtime Sacramento County master gardener and nurseryman Quentyn Young. “In California, we’re lucky. We can grow just about everything.”

Fruit trees also can endure a hot, dry summer better than other crops, notes UC research. The lack of rain can actually improve fruit flavor.

Radio host and podcaster Farmer Fred Hoffman, a lifetime master gardener, cites UC Farm Advisor Emeritus Paul Vossen, who found that fruit trees need water in spring but far less during summer.

“Fruit trees are more deeply rooted (two to three feet) than annual vegetables and can tap into approximately four to six inches of stored water held in a loamy soil,” Vossen wrote. “They develop most of their leaves and shoots before the middle of June. This growth is important for next year’s crop development and for fruit size. Therefore, minimizing drought stress early in the season is the least disruptive to fruit trees. Moisture stress later in the season primarily has the effect of limiting fruit size but also tends to enhance fruit flavor.”

For more than a decade, Young has been working with the orchard at the Fair Oaks Horticulture Center, the master gardeners’ demonstration garden in Fair Oaks Park. The orchard includes more than 50 fruit trees, including citrus.

Many fruit trees need some cold – but not too much. Sacramento is getting fewer “chill hours” (time under 45 degrees), and that can affect stone fruit production, which needs cold nights. Meanwhile, winter nights aren’t getting as cold as they used to, and that’s good for citrus and tropical fruit, which can be frost tender.

Our climate gives most fruit trees what they need when they need it – rainwater in spring to kick-start fruit production, but dry and sunny days while the fruit is maturing.

Pruning, size and water use

At Fair Oaks Horticulture Center, Young has experimented with limited water use with great success. Trees are more efficient; they don’t grow as tall, but they produce more high-quality fruit. Trees are also easier to pick and maintain and need less fertilizer. That saves work and money as well as water.

“It fits into the broader conversation about summer pruning,” he says of limited irrigation. “After harvest, I pretty much stop irrigating.”

The key: Keeping trees smaller. A shorter tree needs less water – and fits into smaller backyards. Summer pruning—cutting back a tree’s rapid spring growth to maintain a tree’s shorter stature and shape—helps maintain a tree’s compact shape and improves flow and light. This combats fungal disease and promotes good fruit production.

“One of the benefits of summer pruning, you keep trees at a small size, just 8 to 10 feet tall,” Young says. “You don’t have to increase irrigation year after year because the tree is staying basically the same height.”

Feed the soil, not the tree

To help keep trees shorter, skip the fertilizer. Except for one round of fertilizer for citrus trees in spring, Young recommends not feeding fruit trees at all.

“Fertilizer tends to produce a lot of extra growth – not extra fruit,” he explains.

Instead, Young recommends surrounding trees with a thick layer of organic mulch such as leaves or wood chips. That feeds the soil (and tree roots) as well as retains moisture.

“A really thick layer of wood chips really helps,” Young says. “I add chips three or four times a year to keep them 4 to 6 inches deep.”

Don’t mound mulch around the trunk or crown. To avoid crown rot, keep a 6-inch circle around the trunk free of mulch.

Smart irrigation at work

The Fair Oaks Horticulture Center orchard uses drip irrigation under a layer of mulch. Mature fruit trees each get 8 to 10 gallons a week in spring. Young increases that to 20 to 30 gallons a week (split into two applications) when temperatures reach 90 degrees in early summer. After harvest, he generally turns the irrigation off, giving trees a monthly drink as needed. The exception is citrus, which maintains weekly summer irrigation as its fruit forms.

Hoffman also recommends deep mulch and drip irrigation. In addition, he swears by a moisture meter, preferably one that’s high tech, to tell him when his fruit trees may need extra irrigation.

“Years ago, I purchased a Rainpoint soil moisture reader that communicates via Bluetooth or WiFi to its companion device in the house,” Hoffman says. “It lets me know when the moisture level is dry, OK, or wet. I let that be my guide.”

Choosing the right trees

What to plant? Start with what you like to eat, Young says.

“Citrus trees are the easiest to grow,” he says, noting they’re worth a little extra water. “No cross-pollination is required; they’re self-fertile. They can grow in containers. Citrus loves our summer heat and winter rain.”

In addition, citrus trees are evergreen with attractive, glossy foliage year-round, fragrant blooms in spring, and attractive fruit.

Young also recommends plums and pluots (a plum-apricot cross). Both have colorful spring blooms in addition to delicious fruit and are more climate resilient than other stone fruit varieties.

Visit the Fair Oaks Horticulture Center

Visitors to the Fair Oaks Hort Center can see for themselves. It’s open monthly to visitors during Open Garden Days. The orchard team regularly holds demonstrations of pruning and other tasks. A mini talk on bare-root trees is planned for the next Open Garden, 9 a.m. to noon Saturday, Jan. 10.

For details and directions: https://ucanr.edu/site/uc-master-gardeners-sacramento-county