Can someone tell me when to plant these bulbs in my zone. On all my regular bulbs (dafs, tulips, crocus etc) I wait for the soil to cool down and that usually means about mid November or later. But this is in the onion family so can I plant them now even though we haven't even had a hard freeze yet? And also, does this plant spread by bulb offsets like the Drumstick Allium? I swear those little pea size bulbs are almost impossible to get rid of and I don't want this Purple Sensation to take over my garden.