When my MG's reach the top of the fence, I weave them back down. If you spend 5 minutes a day "guiding" the vines where you want them to go, that should do it. They will take over the fence but if you don't guide the vines, they will heap up at the top.

Pinching the tips makes the side shoots start growing but I don't find that necessary. The side shoots will get going anyway.

Next year, you're likely to get lots of mutant MG's from cross-pollination with other vines in the area. I've not had any luck with MG's returning the next year that are the same as the parents from this year. You'll probably want to get more seeds next year if you want to make sure you get some that look a certain way.

If you just leave them be they'll likely eventually take over the fence on their own. I have just the opposite problem as the previous poster. I wish I'd never planted Grandpa Otts. It reseeds like mad and comes up everywhere! I fill up trashbags full of vines every spring and summer. Some do cross with my other MG's and produce different looking blooms which I'll sometimes keep but I don't usually let them grow long enough to bloom.

Forgot to say in my first post that MG's are like a standard-shift car. It sounds like yours just shifted into 3rd. The more they grow, the faster they'll grow with lots of heat. They shouldn't be soggy yet not allowed to dry out. You should have a nice, long season to enjoy them in Z9.

If you just leave them be they'll likely eventually take over the fence on their own. True, but I don't like "nakedness" at the bottom of the fence.

I wish I'd never planted Grandpa Otts. It reseeds like mad and comes up everywhere! That's what I like - free flowers!

I fill up trashbags full of vines every spring and summer. I wish I lived close enough to you to at least get these bags for my compost bin. Anything this easy to kill on the first pull I don't consider a problem weed/reseeder.

Some do cross with my other MG's and produce different looking blooms which I'll sometimes keep but I don't usually let them grow long enough to bloom. That's a valid reason a lot of people aren't fans of this MG. If you want consistent colors, the following generation will likely be disappointing.

If you do not grow another Ipomoea purpurea near Grandpa Otts, the seeds from Grandpa Otts vine will come back true to parental type. Iponoea purpurea will readily cross with varieties in the same species. It will not cross with other Ipomoea species such as tricolor (like Heavenly Blue) or nil (like Scarlett O'Hara).