Tomatoes - do I need a bigger cane?

I have some Gardener's Delight tomato plants which are getting very big. I read that I should cut off the growing tip when I have 3-5 flowering trusses, but so far none are flowering. I used 2ft canes but my biggest ones have already grown higher than that. Will my tomato plants grow much higher, and should I buy bigger canes, or will they be ok?

 

Indoors at the moment, in a light place. I need bigger canes, then :D thanks very much

 

Yep, they grow very large indeed. I nipped off the top of the largest one after it grew 5 flower trusses, which came to the top of the larger cane. They are a lot happier with the taller support, and now I have my first tomatoes beginning to ripen :gnthb: