How to Grow Olive Trees in Nevada County

Olives are adapted to hot, dry Mediterranean climates.

Nevada County in Northern California spans several climate zones with a low elevation of 1,000 feet to a high of more than 7,000 feet. Low temperatures in winter can drop to 15 degrees Fahrenheit. Mediterranean natives such as olives need long growing seasons and plenty of heat. Where winter temperatures drop below 12 degrees Fahrenheit, olives should be considered ornamental, as the extreme cold will damage flowers and green fruit.

Things You'll Need

• Drip irrigation emitter system
• Nitrogen fertilizer
• Agricultural lime
• Pruning saw and loppers
• Work gloves
• Frost cloth
• Smudge pot or orchard heater
• Oscillating fans
• Mulch

Instructions

Watering and Fertilizing

1. 

   Drip irrigation prevents crown rot of young trees.

   Prevent crown rot with drip irrigation. Place emitters at the olive's drip line (tree canopy edge). Move the emitters out and add more as the olive grows. One emitter is enough for a 24-inch high sapling.

2. Water newly planted whips and 1-year old trees at 2-1/2 gallons per week throughout the summer (less during winter). Water mature trees at 10 to 20 gallons of water per week summer through fall (less during winter). Do not water during periods of heavy rainfall.

3. 

   Sample the soil and aim for a pH between 7.0 or 7.5.

   Test the soil pH, and add agricultural lime as needed to bring the level to 7.0 or 7.5. Apply 1 lb. of nitrogen to the ground at the drip line in January.

Weeding, Pruning, Thinning

1. Weed a 3-foot circle around olive saplings. Keep the area weed-free the first four years.

2. 

   Prune to maintain an open center.

   Remove suckers to keep olive saplings to one trunk. Branch pruning begins at four years. Remove interior branches to create a "vase" shape.

3. Remove center growth yearly, using thinning cuts. Use thinning cuts on outer branches to maintain shape and size. Olive fruits form on 1-year-old wood. Pruning severely limits crops.

4. 

   KIeep olive trees pruned to 15 feet for easier frost protection.

   Prune to keep the olive to 15 feet. At this height, a frost cloth can be used to protect it from Nevada County winters. Thin heavy crops to prevent alternate bearing and improve fruit size.

Winter Protection

1. 

   Green fruit can be damaged if temperatures drop below 12 degrees Fahrenheit.

   Apply a frost cloth to cover olive trees during severe cold. University of California Davis experts recommend wrapping young trees with palm fronds, cornstalks, cardboard or fiberglass.

2. 

   Oscillating fans move air and generate friction to create heat.

   Place oscillating shop fans around the olive trees. Moving air generates friction that creates heat. Smudge pots are effective, if available. University of California experts recommend using a 100-watt outdoor lamp in the tree's interior.

3. 

   Deep mulch helps prevent root death.

   Apply a 4- to 6-inch deep mulch around the tree roots to prevent root death from freezing.

Tips & Warnings

• Patio heaters can be used to help prevent frost damage. Make sure the heater does not directly touch the tree.

• Olives can be grown in tubs and brought inside a warm porch for the winter in areas such as Nevada County with extremely cold winters.

• Make sure the initial planting site has quick-draining soil. Olives do not like "wet feet".

• Texas A&M Extension experts note that "small leaves and stems die at 17 degrees Fahrenheit, and the entire tree can die if temperatures drop below 10 degrees Fahrenheit."

References

• Nevada County California: Gardening
• California Rare Fruit Growers: Olive
• DaVero Farms: Growing Olive Trees
• University of California Davis Extension: Planting Olive Trees
• Santa Cruz Olive Tree Nursery: Planting and Growing Info

Resources

• Nevada County, California: Nevada County Facts 2009, Climate, pg 3
• Univ. of California Cooperative Extension: Pruning Olive Trees
• University of California Davis: Crop Profile for Olives in California
• Arizona Rare Fruit Growers: Frost Protection for Tropical and Tender Plants
• Univ. of California Div. of Agriculture and Natural Resources: Frost Protection for Citrus and Other Subtropicals