Question
about how tall do they usually grow?

Answer
Lisette,

Growing in the ground in the south in zone 7 where it never gets below 0 they will get 20" tall, they will spread 20" and bloom from March to May. In a large pot they will get 15 inches tall, should not be in a pot with a diameter larger than 14 inches and should be taken indoors when temperatures are going to fall below 32 degrees. If you keep it outdoors in full sun most of the time it should bloom. In a pot be very careful not to keep it constantly wet. If you have more questions write again. Good luck.

Darlene