Blossom end rot
A dark brown to black, sunken, leathery patch forms on the bottom of tomatoes, peppers or courgettes, opposite the stalk. The rest of the plant looks healthy.
A shortage of calcium in the fruit, almost always caused by irregular watering rather than a lack of lime in the soil.
What can you do?
- Pick off affected fruit; it can go on the compost heap, as blossom end rot is not a disease.
- Water regularly and generously so the soil never dries out completely, especially in pots and growing bags.
- Mulch around the plants to keep the soil evenly moist.
Prevention
In warm spells, water daily and evenly, use large pots and don’t overdo high-potassium or high-nitrogen feeds.
When to watch out: July–September