Zone: 3 to 9
Part Sun to Full Sun (the further north you live, the more sun they can take)
Bloom Time: Summer to Fall
Height: 2′ to 4′
Hydrangeas are a plant (in this case, more of a bush) that has a lot of blue varieties.
For many lace-cap hydrangeas (above) and mophead hydrangeas (below), you can actually control how blue the flower is…the more acidic the soil the bluer they will be. If your flowers are pink or just not blue enough for your liking, add some soil acidifier (like you would normally put on rhododendrons), and watch the bloom colors change.
Note: For clarification, this trick won’t work with white hydrangeas, or the Hydrangea paniculata varieties, so you make sure you have one of the pink or blue Hydrangea macrophylla varieties.