My little girl started several from seeds for me around Mothers Day and I planted them in the garden bed in late June. Many of them are now about 8-10 inches tall, and some have begun to climb up the fence. There is only a couple flower buds on the vine. The seed pack indicated it was only an annual for my zone (Toronto Canada - zone 6 I believe) however, from reading the posts here I can see that many find them to be an invasive perenial. I quite like them, and wouldn't mind them sticking around, but not at the expense of my entire garden. Any suggestions to keep them under control?