Care
Indoor vines do well if they are fed with tomato fertiliser each month from a couple of weeks after they have burst into life in the spring until the grapes are ready for picking. Since the bark is fibrous, all kinds of pests over-winter and so scrape the bark away inside the tunnel or greenhouse.
Harvest
The big problem with grapes is that they are full of sugar and unless you have good ventilation between the berries, penicillium fungi will infect the bunches. You can use scissors (some growers have special scissors just for the purpose) to thin out the berries so that the others can grow unencumbered and a good air-flow around the grapes is achieved.
The cardinal rule on harvesting is to cut off the piece of lateral they are growing from so that you do not have to touch the grapes and either contaminate or damage them.
Diseases
We have already spoken of fungal infection. It comes in three forms:
Botrytis occurs in wet conditions and is kept at bay by good pruning.
Downy mildew occurs where the temperature is really hot and the greenhouse or tunnel is very humid.
Powdery mildew forms on the leaves and fruit. You can prune it away, keep the tunnel or greenhouse really clean and spray with Bordeaux Mixture, developed by French monks just for this purpose three hundred years ago and is still considered to be an organic cure by many.
Bacchus
A German white variety that gives excellent juice.
Madeleine Angevine
A citrus flavour, ideal for cool climates, early ripening and a very reliable cropper.
Black Hamburg
The original gardeners grape – fantastic for lots of good fruit, if grown under cover.