Help for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Problem:

I have a 30-40 year old pomegranate in Walnut Creek in our back yard. For the last several years we've had a very poor crop. Maybe 8-15 fruits over the whole tree. In the spring we get lots of flowers but most of them fall off the tree. This year we have ended up with 8 fruits all rather big. I don't know whether or not we are watering it enough. This might have some bearing on my problem. The tree grows lots and lots of branches starting at the lower trunk and continuing up to the top of the tree. Is there anything I should be doing?

CCMG Help Desk Response:
Thank you for contacting the Contra Costa Master Gardeners with your pomegranate question.

Although pomegranates are known to be drought resistant, they do require even moisture during the growing season to set fruit properly. Our historic drought over the past 3 years has affected many plants and trees ability to cope. How are you irrigating your tree? Are you on drip or sprinkler? Are you watering throughout the root zone of the tree or only close to the trunk? Is the rest of your yard that is close by the tree irrigated? Also, does the tree receive at least 6 hours of sun or have other trees shaded out your pomegranate over the years since it was planted? Because of the drought, the soil is very depleted of moisture, even clay soils which retain water for much longer than other soil types are often quite depleted.

Since you mentioned that the tree drops its flowers in the spring there most likely is some cause for the flowers dropping at that time. Besides wind and/or frost, the flower drop could be moisture stress because of the lack of rain earlier. Checking the moisture level of your soil at flowering time would be beneficial. Using a soil probe to check the moisture or just digging down 6 to 12 inches and checking how moist the soil is by hand are the best methods. The following website will explain how to check moisture content by look and feel. http://www.cdpr.ca.gov/docs/county/training/inspprcd/handouts/soil_moist_feel_test.pdf

Mulching your tree will also help with moisture issues. Placing 2 to 4 inches of mulch throughout the root zone of your tree is appropriate, but also provide 12" of clearance around the trunk.

You mentioned that the tree was sending out lots of branches from the lower trunk. Are these suckers coming up from the root zone or actual branches coming off the main trunk?. Does your tree have one central trunk or many trunks coming up from the ground? If the tree is spending a lot of energy making vegetative growth it may not have enough left over to spend on fruit. Removal of water sprouts and/or branches below the bud graft (if any) is also recommended. See the links below for more information on this.

You also mentioned that your tree is 30-40 years old. Some varieties of pomegranate decline after 15 to 20 years of production, although others can live for 100+ years. Most slow down production in the 20-25 year range.

It appears that it may be several reasons for your lack of fruit production. Drought conditions, lack of irrigation and age of the tree being the most likely.

For more information on Pomegranate care please refer to the following websites, including an online book on pomegranate care.
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/pomegranate.html
http://ucanr.edu/sites/Pomegranates/files/164443.pdf

Hope that information helps you. Please feel free to ask more questions if need be. Best of luck with your pomegranate tree.

Contra Costa Master Gardeners Help Desk 

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Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523.

We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, and we are on the web at http://ccmg.ucanr.edu/