Cultivation notes
Grape vines are lovely plants to train along the inside of a greenhouse or conservatory, but they do require a lot of room. One grape vine is plenty for a small greenhouse, but for larger ones allow 1m (3¼ft) between each vine.
Site and soil preparation
Greenhouse grapes grow best when the roots are planted outside the greenhouse, and the vine is trained into the greenhouse through gaps near ground level. However, where this is not possible, the vines can be planted directly into the greenhouse border, but more irrigation will be required.
Double dig the ground and then incorporate a light dressing of wellârotted manure or compost, plus John Innes base fertiliser at 90g per sq m (3oz per sq yd). If the soil is waterlogged, dig a hole 75-90cm (30in-3ft) deep and create a 15cm (6in) drainage layer of brick rubble, gravel or similar in the base.
Planting
Greenhouse vines should be planted at the opposite end to the door, with the stems trained along the side of the greenhouse parallel to the ridge of the roof and running towards the door.
November and December are a good time to plant, as the vine can be pruned back without bleeding at this time of year. Vines should be planted at the same depth that they were in the pot, teasing the roots out so they are well spread out in the planting hole. For more detail on planting technique, see planting trees and shrubs.
Feeding
Just before growth starts in the spring, sprinkle the rooting area with John Innes base fertiliser and dried blood at a rate of 120g per sq m (4oz per sq yd) each.
During the growing season, vines benefit from an occasional extra sprinkling of dried blood at 30g per sq m (1oz per sq yd).
When growth starts in the spring, feed every three weeks with a high potassium feed, such as tomato fertiliser. Once the vine is in full leaf, increase this feeding to weekly intervals. When the grapes start to ripen and colour up, stop feeding with tomato feed, as extra feeding at this time may spoil the flavour of the fruit.
Watering
Water the vine thoroughly every seven to 10 days in the growing season. Vines with the roots inside the greenhouse will need more frequent watering than vines with their roots outside the greenhouse. Where the roots are outside the greenhouse, be guided by the weather and concentrate your watering in dry spells.
Mulching
Just before growth starts in the spring, mulch the rooting area with well-rotted manure.
During the summer, it is a good idea to
Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.
The transfer of pollen grains from a male anther to a female stigma, either within the same flower or between two different flowers. Itâs usually followed by fertilisation and seed production. Some flowers are pollinated by insects or other small creatures, others are wind pollinated. Itâs also possible to pollinate flowers by hand, if you want to breed new plants or ensure successful pollination when there are few natural pollinators.
Growing grapes in containers
Grape vines can be grown in containers of loam-based John Innes No 3 compost. Use a pot about 30-38cm (12-15in) in diameter and depth.
