When Crabapples Fail to Bloom

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Question: My ornamental apple tree didn’t bloom this spring. Why not?

Julie C.

Answer: There are a lot of reasons why a crabapple—or an apple tree, the two just being selections of the same species, Malus pumila—might not bloom. Here are some of the possibilities:

1. Your tree is too young. Like so many fruit trees, crabapples may take several years after planting before they start to flower. Usually 3 or 4, but up to 10 years when conditions aren’t ideal.

2. Your crabapple might be an alternate-year bloomer. It is quite normal for some cultivars to flower and fruit only once every two years. Or to bloom lightly one year and abundantly only the next. This kind of biennial flowering is called “alternate bearing” and it’s largely genetic, a holdover from wild apple trees, most of which bloom biennially. When buying a crabapple tree, try to look for an annual bloomer.

3. The tree is not getting enough sun. If the location has become too shady over the years, this can prevent flowering.

4. The apple tree is diseased. Apple trees suffering from various diseases (scab and fire blight are the worst) may see their flowering reduced or eliminated, especially when the disease goes untreated. It may be necessary to treat certain crabapples with fungicides in order to obtain good flowering.

5. The tree was over pruned or badly pruned. Usually, crabapples require little pruning, only enough to remove branches that are dead, damaged, diseased or rub together. Careful pruning, usually at the end of winter, has little to no impact on flowering, but severe pruning, such as cutting back most branches in an effort to rejuvenate an aging crabapple, often end up eliminating the buds that had overwintered on the tree. Very harsh pruning can also weaken the tree to the point it may take 2 or 3 years to recover and flower again.

6. A late spring frost killed the flower buds. This happens more often on other fruit trees (peaches, cherries, plums, etc.), as apple flower buds are quite cold resistant, but even so, it does happen. Depending on the stage of development of the buds when the frost hits, even a light frost of only 28 °F (-2 °C) can sometimes kill the buds, especially if it is prolonged.

A drought the previous year can negatively affect crabapple blooms. Photo: http://www.treecutting.com.au

7. The apple tree suffered drought the previous year. A dry summer can lead the tree to taking a year off blooming in order to recover from the trauma. If possible, always water your crabapple deeply during drought.

8. The growing conditions simply don’t suit it. Crabapples are actually quite adaptable, but won’t thrive in extremely acid or alkaline soil, where drainage is poor or in zones of constant dryness. To counteract poor soil, another possible problem, apply an all-purpose fertilizer in the spring.

9. The winter was too mild. This happens in areas with Mediterranean climates where crabapples are only very marginal garden choices anyway. Apple trees of all types need a long period of winter cold, often 1000 hours of temperatures below 45 °F (7 ° C), in order to prepare buds to bloom. If you live in such an area (USDA hardiness zones 8 or 9), look for varieties specifically adapted to mild climates that require less than 400 hours of cooling. Even then, if the winter was not cold at all, the tree won’t bloom.

10. The winter was too cold. At the opposite extreme, prolonged winter temperatures much below -40 °F (-40 °C) can kill flower buds and even leaf buds on some crabapples. Usually the tips of the branches are also killed. When this happens, the tree will leaf out late too, that season’s foliage coming from secondary buds buried under the bark … but there are no backup flower buds!  


And there you go: just some of the many reasons why a crabapple tree doesn’t bloom. 

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One thought on “When Crabapples Fail to Bloom

  1. 1. Like citrus and other fruiting trees, the scions of flowering crabapples are obtained from adult growth, so should bloom right away. It would only be too young if it was grown from seed, which is not often done because so many cultivars are not true-to-type.
    2. Are alternate-year bloomers even available anymore? If they are, they shouldn’t be.
    3. This one happens occasionally, but should be a progressive problem, in which the tree bloom a bit less annually for several years.
    4. If the tree is diseased enough to prevent bloom, the lack of bloom would be less of a priority. The disease preventing it from blooming would be very obvious. I mean, you could not miss fire blight if it were serious enough to just inhibit bloom. Because fire blight is a bacterial disease, fungicides do nothing for it.
    5. This one happens sometimes if so-called ‘gardeners’ do not know what they are doing. It happens right near here where the ‘gardeners’ pollard two flowering crabapples just as the flower buds are about to open! However, such problem are very obvious. I mean, you would know if your trees got pollarded. In order for a tree to be completely deprived of bloom, every single bloomable stem would need to be removed.
    6. I have never seen this happen, but I know frost does sometimes kill floral buds of apples in climates with severe winter weather, or where late frosts sometimes happen.
    7. This sounds credible, but I have never seen apple treess in abandoned orchards in our chaparral climate miss a bloom. Even as they succumb to desiccation, they continue to bloom.
    8. This sounds credible as well, but again, I have seen apple trees that are succumbing to intrusion of water form San Franciso Bay continue to bloom.
    9. Although I have never witnessed this, I believe that it happens. In Beverly Hills (in the Los Angeles region) there are only two cultivars of apple that produce fruit after the mild winters (and both are not very good). Because of the lack of chill, the fruit of other cultivars never develops as it should. However, the trees that produce inferior fruit or no fruit at all still bloom. I would guess that there are many cultivars that might not bloom at all there, but like I say, I have never witnessed it.
    10. This is like #6 above. I have never witnessed it, but I know it sometimes happens in more severe climates.

    I think that 6 and 10 are the most likely reasons for apple trees not blooming. 8 and 9 are less likely but certainly more likely than any of the others. 4 and 5 are possibilities, but would have been obvious prior to the missed bloom.

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