I started my plants from seed five years ago. I thought it was worth a try even though I wasn't sure they would grow in my zone 3 garden. I started with probably 12 plants but only two have survived the winters here. I mulch them heavily and they are planted in areas that get a lot of snow cover. One blooms earlier than the other and will get covered with blooms but the other will, many times, just be starting to bloom when frost comes. I'm not sure how big the plants get in warmer areas, but here they usually get 2 1/2 to 3 feet tall.