I planted a grapevine (Seyval Blanc, this was an impulse purchase and planting) last year. It grew like gangbusters, and even gave me a few bunches of grapes this summer. Just about when I picked them, I noticed more grapes suddenly appeared. There seem to be quite a few immature bunches starting up, suggesting I will get a second (and larger) harvest, provided there is enough time before the fall for them to ripen. Is this usual? I can't find anything anywhere about this.