Prune the dwarf in early spring Pruning in winter would subject the tree to diseases while dormant Trim the tree to an odd number of main trunks by trimming to ground level the unwanted trunks Then thin the top of the tree for airflow and appearance Use a granular slow release fertilizer in early spring and mid-summer You should see an increase in growth and blooms that spring Deep water once a week during growth season Do not water if soil is moist or during winter The dwarf crepe myrtle is a beautiful plant and will bring you pleasure for many years if properly cared for!

Dead and crossing branches should be removed at their base. Excess root sprouts should be removed at ground level to produce the number of trunks you desire (I usually go for three to five). Branches and foliage around the bottom third (or less) of the tree can be removed to show off the trunks. That's the only pruning necessary for crape myrtles. More pruning than that and you are likely to get charged with crape murder.

Now is the perfect time to prune . Your trees could definitely use some help . It might be more beneficial to prune some old growth this year and some next year to avoid shocking the largest tree too much . I would leave the branches that have grafted together . A large wound in the bark will allow entry of insects and disease . Crapes seem to look best when they have 3 ,5, or 7 main trunks . That might be a good place to start . You will want to avoid cutting them to the ground . Severe pruning or topping can stimulate basal sprouting which can become a constant nuisance, requiring regular removal . Well-established plants are extremely drought tolerant and have low fertility requirements, although they respond to fertilizer and water with lush growth. You will find more info here - Here is a link that might be useful: Crape Myrtle in Florida

Natchez Crape myrtles develop a wonderful umbrella shape. And they naturally put out more trunks than other myrtles. The trunk density can be considered a form of screening. And the overarching canopy of the tree means that leaves will be hanging down to six or seven feet. The 'limbing down' method really does not look good. (I'm assuming you mean lopping-off large branches, for a 'layered' look) In fact, there's a name for it: Crape Murder. Here in Madison, being a Crape Murderer is equivalent to chewing gum with your mouth open. People will shun you. I suppose, considering that the trees are young, one could clip the outer tips of the branches, regularly, in the way that one shapes and maintains a hedge. That would be quite a chore, though. Me, I'd leave the Natchez totally alone, and let them develop their own architecture. And I'd underplant them with Magnolia Grandiflora, Glossy Viburnum, or a Clumping Bamboo (the kinds that don't send out runners). I wish you'd asked us earlier. There are other Crape Myrtles that assume the dimensions you're describing, all by themselves. Acoma looks like a miniature Natchez, except that it blooms more. On the more mature specimens I've seen, the leaves start at four or five feet - naturally. And I think Catawba would also grow within your desired dimensions. Again, I think that simply leaving Natchez alone, with no pruning at all, will allow it to develop the exaggerated umbrella shape which would yield maximum screening. However, aside from getting precisely the screening effect you'd envisioned, I'm guessing that you chose the right plant. A majestic tree like Natchez, if allowed to develop its own natural architecture, will give your property a scale and an aura that would be hard to match with another plant.