Blossom drop

What you see

Flowers open, then yellow at the little joint on the stalk and fall off without setting fruit. The plant looks completely healthy otherwise, which is what makes it so maddening.

Conditions

Night temperatures above about 24C or below about 13C, very dry air, hot dry wind, or heavy nitrogen feeding that pushes leaf at the expense of fruit. Pollen goes sterile in a heatwave.

Treatment

Nothing to spray. Shade lightly through a heatwave, water deeply and consistently, and tap or gently shake the flower trusses at midday to help self-pollination. Stop high-nitrogen feed and switch to a high-potassium one.

Prevention

Choose heat-set varieties for a hot summer garden. Mulch to keep root temperature steady, and site so plants get afternoon shade in July and August.

Months: June, July, August

Plants

Tomato, Sweet pepper, Chilli, Green bean, Aubergine

Remedies

Wood ash, Seaweed extract, Mulch

The thing people get wrong

Nearly everyone reads flower drop as a nutrient problem and reaches for feed - which, if it is a nitrogen feed, makes it distinctly worse. It is almost always temperature. Once night lows sit above 24C, tomato pollen simply stops working, and no amount of anything in a bottle will change that; you wait for the weather to break, and the plant sets again.