Question:  I just moved into a house that has been empty for several months.  There are neglected citrus and avocado trees in the yard.  How should I care for them?
Susan Finn SLO
 
Maggie King  Master Gardener

Is it any wonder that we love living on the Central Coast?  In most areas of the county, citrus trees and avocados can be grown with relative ease.  They are beautiful year round.  They produce bountiful quantities of delicious fruit.  Few scents are more intoxicating than citrus blossoms.  Surely, one of our most important gardening tasks should be proper care and feeding of these wonderful gifts from nature.  

Lack of proper nutrients can affect fruit size, flavor, color and abundance. Commercial citrus growers use sophisticated techniques to analyze the nutritional needs of their trees.  For the home gardener these tools are not practical, but there is some basic information that will help us care for our orchards.

The primary nutrient that citrus trees need regularly is nitrogen.  For young, non-fruit-bearing trees, frequent, small applications of nitrogen are recommended.  Once maturity is reached, a citrus tree in the home garden should be fertilized at a rate of about one pound of actual nitrogen per tree per year.

Nitrogren deficient

Iron Deficiency

Both phosphorous and potassium should be supplemented occasionally.  Deficiencies in iron, zinc and other minerals are relatively uncommon in California orchards, but when present can usually be treated with foliar sprays.  Deficiencies of minerals show up in characteristic changes in the leaves.

Calculating the amount of ACTUAL nitrogen and other nutrients in any given product can be challenging.  With the variation in citrus types, fertilizer formulations, soil types and specific planting locations, a single recommendation for when to fertilize is not possible, but most experts suggest a good dose of nitrogen in late winter or early spring.  As always, the Master Gardeners are happy to answer your questions. The following websites may be helpful as well.

On March 19, 2011, Mark Gaskell, UCCE Farm Advisor, led  a blueberry workshop at the UCCE Auditorium, our back up location on a rainy day for the Garden of the Seven Sisters.

Photo by Brenda Dawson, UC Davis

Here are some helpful links to more information about growing blueberries:

Mark Gaskell has all of his information for small farm blueberry production  here.

If that link didn't work, his page can always be found at:  http://cesantabarbara.ucdavis.edu

Check out the UC ANR general information for backyard gardening of berries here.

Thank you Mark!

UCCE MASTER GARDENER ADVICE TO GROW BY WORKSHOP

Held: JUNE 19, 2010

Selecting the right subtropical tree for your climate: Some varieties are more tolerant of our “cooler” conditions during the foggy summer months.  Varieties that require a lot of heat may never ripen. Rule of thumb – the more acid in the fruit, the less cold tolerant.

CITRUS VARIETIES  - see last page for San Luis Obispo County

Citrus for the Home Garden in Contra Costa County http://ucce.ucdavis.edu/files/filelibrary/434/32989.pdf

AVOCADO VARIETIES – see last page for San Luis Obispo County

California Rare Fruit Growers
http://www.crfg.org/pubs/ff/avocado.html

Select the best location in your yard and recognize micro-climates that occur even in small areas:

To protect your trees from frost.

Frost/Freeze Protection for Horticultural Crops –   http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html

Frost Protection for Citrus and Other Subtropicals  http://ucanr.org/freepubs/docs/8100.pdf

To plant the tree and suggested spacings:

Avocados: http://homeorchard.ucdavis.edu/Fruits_&_Nuts/Avocado/

Citrus: http://homeorchard.ucdavis.edu/Fruits_&_Nuts/Citrus/

Water needs and irrigation of citrus and avocado:

Mature trees in warmest months will need 60 gallons of water/week.

Watering citrus:  http://ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/citruswatering.html

Citrus for the Home Garden in Contra Costa County http://ucce.ucdavis.edu/files/filelibrary/434/32989.pdf

Watering avocado http://ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/avocadowater.html

Weed Management for citrus and avocado:

Both citrus and avocado are very shallow rooted – only hand weeding and mulch underneath trees

Weed identification and control measures: http://www.ipm.ucdavis.edu/PMG/menu.weeds.html

Fertilizer requirements for citrus and avocado

Suggested application rates of nitrogen - Divide into 2 or 3 applications

• 1st year: 1 tablespoon nitrogen fertilizer 3 times per year, per tree.
• 2nd year: 0.25 lb actual nitrogen per tree
• 3rd year: 0.5lb actual nitrogen per tree
• 4th year: 0.75lb actual nitrogen per tree
• 5th year:1 lb actual nitrogen each year

1 pound of actual nitrogen equals about 5 lb of ammonium sulfate (21% nitrogen)  per year, or 100 lb of composted cow manure each year. Organic fertilizers such as manure, bloodmeal, etc. could be applied in the fall under the tree canopy.

Pest identification, including  methods of reducing pest populations using the least toxic methods.

Avocados - http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/avocados.html

Citrus -  http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/citrus.html

Subtropical Fruits for San Luis Obispo County

For printable version of this handout, click on the attached documents below: