Poor fruit set
Plants that flower well but drop their blossoms or produce few fruit, usually because of temperature, poor pollination or too much nitrogen.
Also known as: Flowers but no fruit, Blossom drop
Symptoms and identification
Flowers open and then wither or drop without forming fruit, or tiny fruit form and fall off. Plants look healthy and leafy but crop little. Fruit that do set may be misshapen.
Causes
Very hot or cold nights stop pollen working, for example above 32 degrees Celsius by day or below 13 degrees by night for tomatoes. Too few pollinating insects, rain at flowering, water stress, shade, and too much nitrogen that grows leaves at the expense of fruit also play a part.
Organic treatment
Hand-pollinate with a soft brush or by shaking tomato flower clusters gently in the middle of the day. Shade plants in extreme heat and cut back on nitrogen feed.
Prevention
Plant at the right time for the climate, attract pollinators with flowers, hand-pollinate squash and cucumbers if bees are scarce, water evenly and use a feed lower in nitrogen once flowering starts.
Chemical treatment (use with care)
Fruit-setting hormone sprays exist for some crops, but they are rarely needed in home gardens. Follow the label if you use one.