I have been growing Morning Glories for a couple of years now, and have been experimenting with the BEST way to allow them to climb. I have tried 1) wooden structures - however they were not tall enough
2) hooks attached under the eavestrough with twine to the ground about 10 feet long - however they get tangled and unmanageable
3) hooks attached under the eavestrough with fish line to the ground about 10 feet - however there needs to be something keep the tension tight
It is difficult to 'train' the morning glories to latch on to the twine and fish line.
I have seen beautiful morning glories growing at commercial sites and they look beautiful, no tangling with each other - very professionally done, how do they do that???
The best way I know to train climbing plants like Morning Glories, Sweet Peas, Clematis in fact all that have twinning tentacles to twine around the framework given.
you have to build the strings, wires or netting in place way before the plants are 3-4 inches tall, however with string, wire or fishing line you need to have some roughness to enable the very new fragile tentacles get a hold while the plants continue to grow upwards, Personally, I remove a lot of the tentacles as they take up energy from the plant and you want the energy to be used for flowers and growth up / over the framework.
You need to plant the seedlings (when large enough to go into the soil) into good humus rich soil to help feed, retain moisture and allow air into the growing medium
that will remain enriched all through the growing season, as the plants begin to grow taller you have to de-tangle if that is happening, and then tie with SOFT green twine, (buy from garden store) to make the ties secure you make a figure 8 type of knot, this is where the little rough areas come in handy so garden canes _tall) are best stuck into the soil and slanting backwards BUT held at the top as these plants get heavy, OK you tie the figure 8 by wrapping the twine twice around the cane / wire. rough string etc, then cross twine over, place the stem of the plant into the cross and LOOSELY tie off the twine holding the stem in place but dont do tight, I use a reef knot, (left over right & under, then right over left ) this type of knot cant come undone easily. If your using wire, depending how thick it is but I use an old pair of wire cutters and make NOTCHES at about 4 inch gaps so the tentacles
have something to grip onto and not slide back down the wire, rough strings will give something to hold onto also.
I'm afraid to say for the type of perfection your wishing to achieve you will have to be prepared to check every day for new shoots needing tied in before they start to tangle around each other, for the first few weeks I would advise nipping off the growing tips of all the plants as this will allow the plants to give out side shoots that will = new side shoots to grow and give off many more flowers, last thing you want is a lovely tall plant and a little flower way up high at the top.
Most people who grow this type of perfection style will also give a liquid feed to help boost the plants and help flowering BUT please dont think more feed means better plants, over feeding can kill the roots, exhaust the plants half way through the growing season and can invite several diseases to attack the the tender foliage that can be a cause of over feeding. Just read the label, start off half strength dose and increase as the season goes on, no new plants require feeding untill they are setting flowers or fruit, so take care with feeding.
Hope you manage to achieve all your ideas as it is a sight to behold however most of us just go with a tumbling of flowers without the straight lines but please show a picture if you can next year, this year is too late for the seeds to get to the stage you require..
Regarding keeping the plants growing another year, I think these are annuals and only grow one season but you can collect the seeds for sewing the next year.
Best of luck and kindest regards.