Do you love the smells and colors of citrus? Citrus can be grown in El Dorado County’s lower elevations or in microclimates that are devoid of cold air basins. We touched on various aspects of growing citrus in El Dorado County in a previous article and will now expand that information.
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There are many varieties of citrus to match tastes and needs. Some trees suitable for El Dorado County are: the Washington navel orange or a Bearss lime that ripen through winter, an Owari Satsuma mandarin ripening October through January, or a Meyer lemon that ripens year round. These varieties are all cold tolerant to the mid 20-degree range and if grown on dwarf rootstock for our area, the tree is more disease resistant. Plus, a smaller tree is easier to care for, harvest and protect from freezes.
How much water a citrus requires depends on soil type, the time of the year and the age of the tree.
Planting the tree’s root ball one inch above the soil line for good drainage and on a mound or in a pot helps to protect the tree from Phytophthora root rot or fungal disease. Water demand for a tree of any age is the highest during spring flush. Water to a depth of two feet and never allow the root system to dry out. Even watering assists in blossom set and will prevent the skin from splitting in navel oranges. A 10-foot diameter, mature orange tree requires from two gallons in January to 15 gallons of water per day in July.
Citrus that is cold tolerant to 25 degrees will not have any difficulties if that temperature lasts for an hour or two.
However, if the low temperature is predicted to last for more than 6 hours: apply water one day before and the day of the anticipated freeze, string holiday lights (C9s) around the tree, tent the tree and wrap the trunk with a thermal blanket or similar material.
Espaliering (pruning the tree to horizontal branches, usually along a wall or support wires) assists with the above, and can provide a decorative focal point in your garden. Remember that citrus trees bear fruit on new growth.
A young non-bearing citrus tree requires ¼ to ½ pound of actual nitrogen/year. A mature tree requires 1 pound of actual nitrogen/year. Applications should be made in early spring at fruit set and once more in June. Follow all fertilizer label directions carefully. Signs of iron deficiency include yellow leaves with green veins. Lastly, citrus grown in pots may need additional micronutrients due to nutrients being leached.
A new disease that affects citrus is called Huanglongbing (HLB). It was discovered last year as far north as the central valley. It is also known as Citrus Greening and is spread by the Asian citrus psyllid.
The disease makes bitter, misshapen fruit and the tree will eventually die. There is no cure. To avoid bringing this devastating disease to El Dorado County, buy trees from a local, reputable nursery. Do not take cuttings from trees. Additional information on growing citrus trees may be found at homeorchard.ucdavis.edu/Fruits_&_Nuts/Citrus or ucanr.org/sites/placernevadasmallfarms/files/63813.pdf
Master Gardeners are available to answer home gardening questions Tuesday through Friday, 9 a.m.-noon by calling 530-621-5512. Walk-ins are welcome at the office, 311 Fair Lane in Placerville.
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