Looking for crape myrtles that will work in zone 6. Would like some that get to 15-20ft and another that gets to 8ft or so. Any suggestions?
Suggest you search in the New England Gardening forum. There was an extensive conversation there about whether it's possible to grow any type of crape myrtle anywhere in New England. Very knowedgeable posters. Good discussion about what other trees have somewhat similar characteristics--since the bottom line is no, it's not possible to grow 'em in z6 or anywhere in New England.
You can definitely grow crepe myrtles in zone 6. I have a Zuni, which is a smaller variety.
At least some crape myrtles are growing well in south central Pa, Harrisburg area. I have 4 'Dynamite' all leafed out with only a very little winter damage.They were planted 4 years ago as 18" container plants and are well over 6 feet now. Neighbors to the north and south of me are growing them as well. As with many other plants, success in growing these may depend on site and soil.
Some information on microclimates to help you locate the warmer areas of your garden:
I should have been more specific- it's not just that you can grow them in zone 6 with special effort, but that there are crepe myrtles that are hardy to zone 6. I think they tend to be the smaller ones, such as the Zuni I mentioned. (I do know someone who grows one in zone 5).
I have heard a lot of talk about Crepe Myrtles...I might see if I can get one too. I like that it would be original in my cookie cutter neighborhood!
A quick google search came up with "Natchez" Crepe Myrtle
Lagerstroemia fauriei is reliably hardy as far north as USDA Hardiness Zone 6.
I have a Muskogee Crapemyrtle that has done very well. It is planted off the corner of the house, southern exposure, and windy as all heck. It's been in for 5 years and I have had no problems with dieback or winter damage. With the crazy cool, wet summer last year it flowered later than normal, well into October and had flowers and red and yellow fall foliage at the same time. It was planted at 8'-10' tall and is now a good 12'+ with an 8'-10' head. I also have some Pokemoke Crapemyrtle, a low variety. They have also have been in 5 years. Planted at 15"-18" wide, now 2 1/2' - 3' wide by 18" tall. Some are planted 3' from the street in pretty harsh conditions and are doinf well. I tried these at my house before being comfortable recommending them to clients. I now use them frequently. My experience shows that they do not do well/survive if planted in the fall. Spring and early summer planting only.