Tony Dickerson answers your questions
Q Why do my pot-grown gooseberry bushes do so badly? Dennis Faulkner, Torquay, Devon
A Growing fruit in containers is great where space is limited and gardens are small, but it’s a high maintenance operation. The reason your flower buds and fruitlets turn brown and fall is the plants are too dry. Pots need to be in full sun and watered generously in warm weather.
Where bushes are stripped of foliage it’s due to gooseberry sawfly larvae. These are green, caterpillar-like larvae about 2cm (¾in) long with black spots. They are voracious feeders and defoliate bushes very quickly.
Either hand pick or spray with an insecticide approved for use on fruit. The main disease of gooseberries is gooseberry mildew, which can be kept in check with regular applications of SB Plant Invigorator or a similar product. A number of varieties including ‘Greenfinch’, ‘Invicta’ and ‘Hinnonmaki’ show good resistance.
When growing in containers choose a pot at least 45cm (1½ft) in depth and diameter. To avoid plants becoming root bound repot every second year after leaf fall using a good-quality John Innes No 3 with some added multi-purpose and grit. Incorporate a controlled-release fertiliser at the recommended rate. At the same time root prune, removing long, circling roots. Replace the top layer of potting compost in alternate years, adding fresh controlled-release fertiliser.
Prune gooseberries in late winter. The aim is to produce a bush with a strong framework of about eight main branches on a short leg. Branches should be well-spaced and the centre open. Achieve this by cutting back shoots on a young plant by three quarters. In the second winter select your eight shoots and shorten each by up to a quarter. Shorten remaining shoots to four buds and remove any that are crossing.
In subsequent winters prune back all new shoots on the main branches to about 8cm (3in). If the main branches are too long tip prune to three or four buds of the new growth. Cutting back too hard results in very little fruit.