Fertilizing Fruit Trees and Information on Chill Hours"

Advice for the Home Gardener from the
Help Desk of the UC Master Gardeners of
Contra Costa County

Home Gardener Request:  We're finally jumping into fully caring for our mini-orchard here in Mid-County. Could you please point us to a good reference book for that task... Also, we are getting acquainted with chill hours for growing and/or buying various fruit trees, especially for apple, plum and pear trees. Where can we find local info on chill hours?

CCMG Help Desk Response:  Thanks for calling the UC Master Gardener Program Help Desk this morning with your questions about what and how to feed your apple, plum and pear trees and year to date chill hours for your area.

After some further thought, I'd like to suggest that you may want to complete a soil test of your orchard to see what your soil may be lacking before fertilizing your trees this spring as that will drive what and how much to feed.

I found that the UC Home Orchard: Growing Your Own Deciduous Fruit and Nut Trees book supports soil testing before adding potentially unnecessary fertilizers to your soil:

Although deciduous fruit trees require many nutrients for tree growth and fruit production, those grown in backyard settings in typical sandy loam to clay loam soils with proper irrigation rarely need to be fertilized.  Nutrient deficiencies, when encountered, are generally limited to nitrogen, potassium, iron, and zinc, and on rare occasions, boron.  Unless your soil has a known nutrient deficiency, regular applications of fertilizer usually are not necessary in a mature orchard.

Below is a link to a list of soil testing companies for you to choose from. When you contact one of the labs, they will give you instructions on how to take the sample and prepare it for shipping. Some of the labs listed also have helpful information on how to interpret the results including the amounts of necessary additives your soil needs. Soil testing companies:  https://ucanr.edu/sites/ccmg/files/51308.pdf

Below is a link to information from the UC California Backyard Orchard website.  It includes information on common elements for normal growth and amounts to feed by age of the tree rather than size:  http://homeorchard.ucanr.edu/The_Big_Picture/Fertilization/

The links below include helpful seasonal information for growing fruit trees:

Apples & Pears: Calendar of Operations for Home Gardeners: http://homeorchard.ucdavis.edu/7258.pdf

Plums: Calendar of Operations for Home Gardeners: http://homeorchard.ucdavis.edu/7262.pdf

And finally, here is the link I used to find current information on chill hours in Contra Costa County.  I selected the El Cerrito Weather Station for a chill hour to date and historical information: 
https://ucanr.edu/chillcalc/?controller=station&action=reportresults&STATION=213

You may want to consider purchasing The UC Home Orchard: Growing Your Own Deciduous Fruit and Nut Trees book as it was developed especially for backyard orchardists, rare fruit growers, and small-scale growers.  It is available through various online booksellers and through the UCANR Catalog: https://anrcatalog.ucanr.edu/

I hope you find this information helpful.  Please let us know if you have any additional questions.

Help Desk of the UC Master Gardener Program of Contra Costa County (SLH)

Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.