Why Do Flowers Fall Off?
In some cases, blossom drop in plants is normal. For instance, male flowers naturally drop from vegetable plants after a few days. Many vegetables, like squash, begin producing male flowers as much as two weeks before the first female flower bloom. That being said, healthy blossoms can suddenly drop from plants due to inadequate pollination, environmental factors, low soil fertility, and thrips.
Pollination
When healthy blooms fall off vegetables and other flowering plants a few days after they open, the flowers probably weren’t pollinated. Here are some of the reasons flowers don’t get pollinated: High daytime temperatures or low night temperatures prevent pollination. The range of acceptable temperatures varies from plant to plant, but you can expect to lose some flowers when daytime temperatures are above 85 degrees F. (29 C.), or night temperatures drop below 55 degrees F. (12 C.). Tomatoes drop their flowers when nighttime temperatures remain above 75 degrees F. (23 C.). With the decline in honeybee populations, the lack of insect pollinators has become a major problem in some areas. Limit the use of insecticides, especially from midmorning until midafternoon when bees are out and about. Honeybees and several other insect pollinators don’t fly on cold or rainy days.
Environmental
Temperature fluctuations, such as those above, greatly affect plant blooms. In addition to flower drop during high temps, cooler temperatures following blossom set can also lead to healthy blossoms falling off. Insufficient light, whether it’s too much or too little, can also contribute to healthy flowers dropping off plants.
Soil Fertility
Low soil fertility can inhibit the continuance of healthy blooming. Rather than fertilizing at the onset of blooming, apply fertilizers at least four to six weeks prior to flowering.
Thrips
Thrips can also cause buds and flowers to fall off of plants. These tiny pests get inside buds and feed on the petals. Although thrips are difficult to see without magnification, you can see the blotching and streaking on the petals. Spinosad is an environmentally safe insecticide that kills thrips, but it is difficult to bring insecticides in contact with thrips because they are enclosed inside the buds. Non-chemical control options include controlling nearby grass and weeds, picking off and destroying infested buds, and regularly spraying the plants with water.
Flower Drop Tips
The blossoms on both vegetable and ornamental plants drop when the plant experiences stress. Here are some tips to minimize stress in the garden:
Keep the soil evenly moist. Mulch helps prevent water evaporation and keeps the moisture level even. Water slowly and deeply in the absence of rain, and never allow the soil to become dry. Plants experience stress when they don’t have the proper nutrients. Most plants respond well to feeding in spring and midsummer with a layer of compost or a slow-release fertilizer. Some plants have special needs, and your seed packet or plant tag should explain how to feed them. Plant flowers and vegetables in a location where they will get the right amount of sunlight. Both too little and too much sun can stress a plant and cause the flowers to drop.
If you follow these tips, you’ll have healthy plants with natural resistance to insects and diseases. If you notice signs of infestation, treat the plant as soon as possible.
