By Jackhill
United Kingdom 
I have two grape vines from the Hampton Court great vine, they are indoors with the roots outside . They have been growing for five years but only last year did they produce any flowers and three bunches resulted. This year only one bunch has appeared. How can I induce the plants to flower ??
18 Jul, 2017
Answers
Also when you say 'indoors' do you mean in a greenhouse?
18 Jul, 2017
Back to the main stem {as I do with my outdoor vine which at present is loaded with fruit]
Indoors means in this case a conservatory Regards jack Hill
1 Aug, 2017
Hi Jack, you've been pruning them back to hard, indoor vines are pruned using the rod and spur system, copy and paste the RHS link below to see how to do this in late November or December.
https://www.rhs.org.uk/advice/profile?PID=286
1 Aug, 2017
Did you prune the vines in winter? If so how far did you cut them back?
18 Jul, 2017