@CDsSister I'd say May and June are the best months for planting, July & Aug. might be OK, after that can be tricky if we have a severe winter.
@Eviesmummy, yes, if the plants struggle through a bad winter, mine eventually catch up the next year. As far as importing plants, they need to pass inspection from the country of origin and again when they reach the U.S. The big thing is the expense to have the original inspection and cost of postage - it gets
very expensive. It can also take a long time to ship and go through customs which puts a lot of stress on the plants.