Well it depends on how many brown leaves there are. Justa few shouldn't be problem as long as you don't keep gettint more..It may have got too dry in the recent (short!) hot spell. Its not too late to put it in the border. Its mainly bare root shrubs that need to be moved when dormant.
Keep it well watered when you plant it - a good soak is better than frequent small amounts.

I agree with steragram. planting it from a container is fine. Dig the hole at least 1.5 -2 times the size of the pot and mix the soil you have dug out with compost add a little to the hole then plant it and back fill with the rest of the soil/compost mix. water well for several weeks until it is settled in. plant the plant to the same depth as it is in the pot.