Blossom Drop

Why do the flowers keep falling off your tomato, squash, melon, and bean plants, and citrus trees?


This condition is called blossom drop. Blossom drop can be caused by several factors, most of which are perfectly normal. Others, not so much. Generally speaking, unfertilized flowers are kicked to the curb. Here are some species-specific causes of blossom drop.


Citrus June drop

Most citrus trees will produce far more flowers than they could possibly bring to maturity. When the tree decides it has enough fertilized flowers, usually around June, the rest are discarded. It’s nothing to worry about.


Cucurbit blossom drop

The first flowers on your melons, winter or summer squash, and cucumber are generally male. These drop naturally after a brief appearance. If female blossoms start falling off, it is usually because of thrip damage, poor soil fertility, environmental factors, or inadequate pollination. You can attract more bees and other pollinators to your garden by adding yarrow and bee balm. You can also allow onions, carrots, and fennel to go to seed. These plants will all provide pollen and nectar to beneficial insects that should increase pollination rates. If that doesn’t work, you can always try hand-pollinating.


Bean blossom drop
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Temperatures over 90°F will cause bean flowers to abort. This can also occur with insufficient irrigation and poor air quality due to smog or fires. If you know your summer temperatures are likely to go over that threshold, try planting beans earlier or later in the season.

Blossom drop on tomatoes (Kate Russell)

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Tomato and pepper blossom drop

Tomatoes and peppers often drop their blossoms when environmental conditions are unfavorable. This might mean any of the following:

• temperatures are too high or too low
• insufficient irrigation
• hot, dry winds
• excessive nitrogen
• insufficient potassium, phosphorous, or nitrogen (highly unlikely in the Bay Area)
• overcrowding
• damage from the tarnished plant bug
• verticillium wilt
• fusarium wilt

How to reduce blossom drop

Use these handy tips to reduce blossom drop in your garden:

• maintain good soil fertility
• irrigate regularly
• space plants far enough apart that pollinators can find flowers
• protect plants from strong, hot wind

The good news about blossom drop

Luckily, when environmental conditions cause blossom drop, most plants will simply try again, producing a second crop of blossoms.