You can plant pot grown shrubs at any time that the ground isn't frozen. If you plant now you'll need to be very careful to give enough water during the rest of the summer - if we get one. November - March is the time for planting bare-root shrubs and trees that are much cheaper than pot-grown.

October is a traditional time to plant shrubs as the weather typically gives plenty of rain for the next few months to help them get established, and the soil is still relatively warm so the roots can grow.

Newly planted shrubs need to be looked after carefully for at least the first year. They need at least 2 gallons of water each, not applied as a little trickle every day, but a thorough watering once a week, so that the water gets down to where the roots are, and lower - to where you want them to grow. If it rains heavily that's the job done for you, for a few days, provided the plants aren't in rain shadow.

Also remember that both rhododendrons and azaleas (which are actually rhodos too) need acid soil and semi-shade to do well.