Keep greenhouse tomatoes regularly watered throughout the summer. If the compost is allowed to dry out, the developing tomato fruits are prone to moisture-related problems, including blossom-end rot (the fruit bases turn dark brown and tough-skinned) and splitting, and can easily be ruined. For this reason, check the compost every morning and evening. Regular liquid feeding with an organic tomato fertiliser is also essential: this should begin when the first tomato fruits have set.

If your weigela has finished flowering, remove some of the oldest and weakest stems. Cut them back to ground level to keep the plant healthy. The spent flower stems can also be cut back to young shoots or leaves.

Kohlrabi is an exotic vegetable that produces spherical and swollen stem bases (globes). These can be grated and sliced onto salads – they are juicy, with a nutty flavour – or cooked and added to soups and stews. The purple-skinned varieties, such as ‘Delicacy Purple’ and ‘Purple Vienna’, are hardy, and the seeds can be sown now.

Select a sunny spot with a light, welldrained soil and sow the seeds in ½in-deep drills. Once the seedlings emerge and are large enough to handle, thin them to 6in apart and keep the ground moist in dry weather. The kohlrabi can be harvested throughout autumn and early winter, when they are midway between the size of a golf ball and a tennis ball - use on the same day as picking, because the plants deteriorate quickly once out of the ground.

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