What’s wrong with my tomatoes?
QI’m having trouble with tomatoes. Some flowers dropped before fruit set. A few have split, while others have rotten bases. Should I increase feeding?
Mandy Audley, Frinton-on-Sea
AGrowing tomatoes requires a little bit of experience, which is quickly gained over a couple of seasons. I’m assuming you are growing your tomatoes in a greenhouse.
Common problems include blossom end rot, the symptoms of which you describe well. The base of the fruit develops a dark coloured patch that increases in size as fruit forms.
The rest of the individual fruit may go on to ripen but it will be highly disfigured. This is a problem relating to calcium deficiency, caused by the compost being too wet and then too dry.
Regular watering ensures a constant movement of calcium through the plant. Tomato plants like to be maintained at a reasonably damp level, which promotes even growth and development. But watering problems are common where plants are in containers or growing bags.
Split fruit again relates to watering (I get the impression you are watering well then allowing the compost to dry out). Dry roots that are suddenly watered can lead to a rapid increase in the size of the fruit, which causes the skin to split.
Another common problem is magnesium deficiency, which can be brought on by regular feeding with a high potash fertiliser that contains small amounts of magnesium. Symptoms are discoloration of lower leaves, which gradually moves up the plant. Areas between leaf veins turn yellow. It’s easily rectified by applying a foliar spray of Epsom salts, using ½oz in a pint of water.
Flowers dropping off before they set may indicate that plant roots and the greenhouse atmosphere is too dry, or it could be down to a lack of pollination. Damping down the greenhouse floor using a watering can will raise humidity and lead to lower temperatures.
Try hand-pollinating if flowers still fail to set. Use a small paintbrush and move pollen from one flower to the next. Do this twice a week to encourage better crops.