Now is the perfect time to prepare to plant bare-root fruit trees, or to transplant them from a pot into the ground.
The University of California’s Division of Agriculture and Natural Resources (ANR) provides guidelines to help home gardeners and orchardists understand what fruit trees need: how to plant them and care for them so that harvest is simplified and safe. But first, think carefully about what fruit trees you want to plant, because you’re the one who will nurture them and reap the harvest.
Do you like apples? Peaches or nectarines? Pomegranates or persimmons? Kiwis or plums? Figs or nuts? The first step in fruit-tree selection is deciding what fruits you enjoy eating fresh and whether you also enjoy them canned, frozen or dehydrated. Make a list of the fruits you would most like to harvest at home.
At the nursery, you will need to choose cultivars (varieties) of the fruits on your list. Before committing, read what experts have to say about each variety’s flavor and ripening time. For help, consult UC ANR publication 8261: “Selecting Fruit, Nut, and Berry Crops.” It is available online at http://ucanr.edu/Publications_524/. Use the search function to find a specific publication.
Size matters. You need to be sure you have enough space in your garden to accommodate the tree when it’s full-grown. At the nursery, avoid undersized bare-root specimens with trunks less than 3/8-inch in diameter, and oversized trees with trunks more than 5/8-inch in diameter. Measure just above the graft union with calipers. The graft union is where the rootstock meets the scion, the fruiting variety. For bare-root trees, look for a well-healed graft union. Read the label to learn the size of the mature tree. Do you have that much room?
The label should also indicate the type of rootstock used. Is it a dwarfing, semi-dwarfing or standard rootstock? Each of these affects the vigor and mature size of the tree, as well as the amount of pruning required.
Know the variety’s chill requirements. Each fruit-tree cultivar requires a certain amount of winter chill to break dormancy. In winter, the tree’s internal processes are in a state of rest, or dormancy, due to the presence of growth inhibitors. Growth will not occur even under ideal temperatures. This phenomenon prevents fruit trees from beginning to grow during an atypical period of warm weather only to be damaged by frost later.
Trees break dormancy when cold temperatures break down the growth inhibitors. This process is called vernalization or “winter chill.” Each fruit-tree variety requires a certain number of hours of chilling (between 32 degrees Fahrenheit and 45 degrees Fahrenheit) to break dormancy. Then, in spring, active growth resumes. Most of Northern California receives between 800 and 1,500 “chill hours” each winter. Be sure to note the winter-chill requirements on each cultivar’s label.
Fruit trees need at least eight hours of full sun during the growing season. In Napa County, citrus trees will probably need some frost management. Consult UC ANR publication 8100 for frost-management strategies (http://homeorchard.ucdavis.edu/8100.pdf).
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Some fruit trees are self-fruitful, meaning the blossoms are pollinated by another flower on the same tree. Other fruit trees need pollen from a second tree, a related cultivar. Check the label for this information.
Good drainage is vital. You probably won’t need to amend your garden soil, but avoid compacting it by walking on it when it is wet. Pockets of air in the soil encourage root growth.
If you can’t plant a bare-root tree right away, heel it in: set it on its side and temporarily cover the roots with soil prior to permanent planting. But don’t leave it that way for more than a couple of days or it may begin to grow.
If you have space, consider planting early-, mid- and late-season varieties of a fruit you love so you can extend the harvest.
Dig a planting hole at least twice as wide as the spread of the tree’s roots but no deeper than the depth of the root ball. Mound some soil at the bottom of the hole and spread the roots around it. Then backfill with the soil you removed. Fill a little, tamp down gently, then fill some more.
After planting a potted tree, the soil line on the trunk should be two to three inches above the surrounding ground. The graft union should face northeast to avoid sunburn.
Finally, consult UC ANR publication 8048 (“Fruit Trees: Planting and Care of Young Trees”), available online. Post-planting tasks include immediate pruning of the young tree, sunburn protection and irrigation. Home gardeners will also find “The Home Orchard” by P. Geisel and C. Ingels an invaluable resource.
Workshop: UC Master Gardeners of Napa County will conduct a workshop on “Fruit Tree Selection and Planting” on Saturday, Nov. 18, from 9:30-11:30 a.m. at the UC Cooperative Extension office, 1710 Soscol Ave., Napa. It’s the perfect time to get the soil ready to plant bare-root fruit trees, or to plant from a pot into the ground. Learn about soil types, site selection, site preparation and first-year care. Prepare your garden now so your new fruit trees will thrive. Learn what fruit tree varieties perform well in Napa County so you can choose wisely. Online registration (credit card only); Mail-in form (cash or check only).