When flowers drop before fruiting on your plants, three main problems are usually to blame. Poor pollination tops the list for most gardeners. Heat or cold stress comes next in line. Nutrient gaps round out the trio. Any of these issues can cause your plant to shed blooms without making fruit.
I dealt with this problem during a heat wave last summer with my tomato plants. The flowers opened just fine each morning looking healthy and yellow. But none of them set fruit during that hot week. They just dried up and fell to the ground below. Temps had climbed above 85°F (29°C) for days and killed the pollen.
The biology behind this makes sense when you think about what flowers need to do. A flower must get pollinated to start making fruit on the vine. Pollen has to land on the stigma and grow a tube down to the ovary. If this process fails for any reason, the flower never gets the signal to develop fruit tissue.
When pollination fails, your plant drops the useless flower to save energy. Making fruit takes a lot of resources from the plant. Why waste those resources on a flower that will never make seeds? The plant cuts its losses and tries again with the next round of blooms.
Temperature ranks high among blossom drop causes for warm-season crops. Tomatoes drop their flowers when temps rise above 85°F (29°C) or fall below 55°F (13°C) at night. Peppers react the same way to these extremes. High heat kills pollen before it can work. Cold nights prevent pollen tubes from growing.
Nutrient problems can also make your flowers fall off before they set fruit. Low calcium causes blossom drop and blossom end rot in tomatoes. Lack of boron affects how pollen develops inside the flower. Both problems are easy to miss since the plants may look healthy in other ways.
Water stress adds to the issue for many gardeners growing in containers or hot climates. Plants that swing between drought and soggy soil put stress on their blooms. This stress can trigger flower drop even when temps and nutrients are fine. Steady moisture keeps blooms happy.
Now for flower drop solutions you can try in your own garden. During heat waves, put up a shade cloth over your plants during the hottest part of the day. This can drop temps by 10-15 degrees under the cloth. Your flowers stand a better chance of setting fruit in cooler air.
Hand pollinate your flowers when bees are scarce or weather is bad outside. Use a small brush or cotton swab to move pollen from one flower to another. Do this in the morning when flowers are fresh and pollen is ready. This simple step can boost fruit set by 50% or more in my experience.
Add calcium and boron to your soil if you suspect nutrient gaps are causing the problem. Crusite lime adds calcium over time to your garden beds. A tiny bit of borax mixed in water gives plants the boron they need. Water your plants on a steady schedule to avoid stress from drought or soggy roots. These flower drop solutions work for most common garden crops.
Read the full article: 6 Plant Growth Stages Explained Simply
