This is my first post! I'm a gardening newbie.

Last year I planted 2 'hopi' crape myrtles as a border plant. The nursery had a sign that said 5' x 5' while the container said 6'-10'. I'm assuming that 5' x 5' are the dimensions for our region, that 10' would be further south.

Both of my myrtles grew a lot this year so far. They are about 3.5 feet by 3 feet right now. Looking at pictures last year, they are about 20% larger and fuller.

My question is, are those 5x5 dimensions correct? If they are, I think I need to move them a little closer together. Now that I've examined my garden over the year, there is just too much space. However, if they are going to continue to grow so quickly and will get to be 10' x 10', I won't mind them where they are. I'd like to only move them once of course and the sooner the better.

In the meantime, can anyone recommend a 6' tall "filler" plant that will at least provide some privacy for most of Late Spring/Summer/Early Fall. I could keep these between the myrtles for a couple of more years until the myrtles take over.

As of right now it goes

Myrtle, Tinkerbell Lilac, Myrtle, Pyrocantha

However, if the myrtles won't be getting beyond 5x5, I'd like it to be.

Myrtle, Tinkerbell, myrtle, Fairytale lilac, Pyrocantha