Tales from a Desert Gardener
by Steve Fazio, Horticulturist

“My fruit tree is dropping all of its blossoms – my fruit tree didn’t bloom this year – fruit is falling from the tree.” These remarks are expressed by many gardeners in connection with citrus and deciduous fruit trees. What caused these problems? Some are related to cultural management practices, temperature; others are normal plant responses.

Citrus trees will cause the greatest concern for most gardeners – they will shed many blossoms and later in the season, fruit as large as walnuts will fall to the ground. All varieties of citrus produce more blossoms than the tree can possibly set – approximately 98% will fall even under the best cultural management practices. If 2% of the blossoms set fruit, this would be considered a heavy commercial crop. This is a natural behavior of the trees, but failure for 2% to set fruit is related to many factors. Late spring frost that occurs during bloom period causes a weakening or death of the abscission layer. This layer of cells connects the flower to the tree – sub-freezing conditions injure the cells, and blossom drop will result.

Trees that were not fertilized prior to the bloom period often drop excess number of blossoms, especially if soil fertility was extremely low. The tree is reacting in a natural manner – it is ridding itself of a burden. Improper irrigation is also responsible for blossom drop. Fruit trees in the blooming stage require very special attention in connection with soil moisture – they should never be allowed to stress for water – this will weaken the connecting layer. Trees should not be over watered at this stage – irrigation should be maintained on the same level used during the growing season – irrigate when soil examination reveals a need for moisture, but do it on a more careful basis during bloom.

Some varieties of citrus may fail to produce blossoms – gardeners will often state, “Last year my tree had a profusion of blossoms, and I had a heavy crop of fruit – no blossoms are evident this year.” This condition is common with some varieties of mandarins – the Kinnow mandarin is one of the main culprits. This condition is referred to as “alternate bearing” – a heavy bloom one year and none the next. This occurs on other citrus varieties, but not as pronounced as the mandarins. Commercial growers will often state, “My orange and grapefruit crop is on the light year cycle.” Others may state, “My crop is on the heavy cycle.” Trees that produce a heavy crop one year will usually produce a lighter crop the following year – this is alternate bearing on the light side.

The heartbreak of growing citrus is called “June drop.” This occurs when fruit the size of a pea or as large as a walnut fall from the tree. It is caused by high temperatures and low humidity – it will be evident starting in May and extending through the month of June. Trees should be checked at frequent intervals during the stress period for soil moisture – fruit drop is aggravated by moisture deficiency.

Harlow Gardens
5620 E. Pima St., Tucson, AZ 85712
(520) 298-3303


  • Posted: August 17th, 20128:07 am
    John C

    I live in Mesa AZ….This year my navel orange had no blossoms therefore no fruit growing. The leaves look green and shiny. I am expecting that maybe it could have been water as after I watered copiously the trunk sprouted lots of those little outgrowths of leaves.
    My question is this. I do not want to lose this tree. What is the best thing to do now to make sure it will be OK for next year?

  • Posted: August 17th, 201210:29 am
    John C

    It is a little unclear (not sure about why you were watering ‘copiously’ or exactly what the ‘little outgrowths’ look like) what is happening to your citrus. However, to make sure your tree is OK for next year, simply continue to water on a regular schedule and fertilize around Valentine’s, Memorial, and Labor Day. If you could send us some digital photos at we could be more helpful.

  • Posted: April 20th, 20154:08 pm
    John C

    Thank you!
    information was most helpful, you answered my question. I’ll try a better watering & fertilizing schedule.

  • Posted: September 25th, 20157:22 am
    John C

    My naval and blood orange trees are dropping fruit that are the size of tennis balls. l have lost almost half of the fruit. The
    Trees are in very good condition and this is the first this has happened.

  • Posted: October 14th, 201510:47 am
    John C

    Hello Glynn,
    Citrus fruit drop this time of year and of the size indicated is definitely unusual. There is a reason but we may not be able to pinpoint it.
    Most fruit drop because the tree is under stress. This could include too much water, too little water, or too much fertilizer. In rare circumstances it could include high winds and hail.
    So, think about whether any of these situations could apply to your situation.
    Thank you,
    Cara Bohardt
    Assistant Administrator

  • Posted: March 11th, 20165:21 pm
    John C

    I was told by the woman that gave me a small orange tree (30″) that when blossoms start to show, that I should stop watering it or the blossoms would fall off. Any truth?

  • Posted: March 22nd, 20162:50 pm
    John C

    Hi Larry,
    This is not what we would recommend. Water your citrus on a regular basis with slow deep waterings.

    Thank you,

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