Morning glories like to twine around themselves and work their way back up. Its very difficult to make them grow downward. I've personally never seen it. I have them all over my yard and they all do the same thing. They will catch on to whatever they can and grow upward.

They do dangle if they have nothing to attach to, but if there are other plants nearby they'll twine all over those. They also don't seem to grow much without something to twine on -- they don't act like your typical cascading/trailing plant.

Here's one solution I've worked out:

Attach lengths of twine or fishing line from the window box to the top of your balcony, and let them grow up them. When they've got enough length (doesn't take long!), detach the strings and let them dangle down. Attach the loose ends at floor level, and there you have it. They grew up, but they're down where you want them and can continue to grow up from there.

Twining back up on themselves doesn't seem to harm, but if you want them to start back upward on a new string, you can attach a new string near the old one at the floor level and train them in the right direction. OR, you can start this project with a double-length of string (with the excess wound up and out of the way, at the top) and extend the rest of the string upward when you drop the plant down.

One easier option is to put the container at floor level and just let them grow up.

they definitely twine back up on themselves, and even start conrugating and make a rope upward.

Convolvulus morning glories are supposed to trail better than their cousins the ipoemas (the ones we usually think of when someone says mg).

This is my first posting on this forum (I was actually looking for planting ideas for windowboxes and urns), but I couldn't help offering up my experience because I tried to do the exact same thing last year, because I thought that the bright blue of my Heavenly Blue MG would look great trailing 5 feet below the box. Here's what happened and (I think) why:

I used 1 seedling in each corner of the box away from anything else trailing (to keep the tangling to a minium). I still had to un-tangle it almost daily if I didn't want it to knot upwards into a rope (as Yanggers noted it wants to do). It did look pretty when it flowered, tho.

BUT, it didn't flower nearly as well as the ones growing on the ground. I've been told by more experienced gardeners that it's because MG's won't flower well when fertilized or in rich soil, and those are the conditions in a window box.

Not really worth the effort, I'm afraid.

May you have better luck.

Jessallyn