Try growing less hardy and frost-tender fruits in the glasshouse or conservatory, but be aware of several potential problems.
Peaches, nectarines and apricots
Frost-free conservatories or glasshouses will protect blossom from frost and the foliage from peach-leaf curl (which is spread by rain-splash). Insects are scarce under glass in early spring, so hand-pollinate with a fine paintbrush. Ventilate in winter to harden the new wood.
Melons
These need a warm, heated, sunny glasshouse (min 18°C/64°F). Provide shade netting in hot weather. Ventilate during flowering, to allow insects in, and keep a dry atmosphere. If necessary, hand-pollinate by pressing the male into the female flowers – the latter have swellings behind them.
Citrus
Suitable for sunny conservatories with night temperatures of around 7°C (45°F) in winter, citrus plants benefit from being moved outside in warm summers. Beware excessive dryness (indoors and out) and glasshouse pests such as scale insect and red spider mite. Read more on growing citrus
Grapes
Plant the roots outside and train vine cordons into an unheated glasshouse. Shade and ventilate in hot weather. Lay dry mulch on the floor and tap the branches during flowering to aid fruit-set. Powdery mildew and scorch can be problems under glass. Try grapes which don’t do well outdoors, such as Muscat varieties. Read more on growing grapes
Other fruit to try
Figs
Although grown outside in mild regions, figs do well under frost-free cover in cold areas. Try warm-climate cultivars like ‘Bourjassotte Grise’ or ‘Rouge de Bordeaux’. Read more on growing figs
Kiwi Fruit
The cultivar ‘Jenny’ is self-fertile, compact and ideal for a frost-free glasshouse. Sufficient space and frequent summer irrigation are required. Read more on growing kiwi fruit
Physalis
An easy annual fruit for a frost-free glasshouse or polytunnel, grow these like you would bush cherry tomatoes.