a 20 foot container? That is huge! I do see a problem with planting 2 butterfly bushes 1 foot apart anywhere. Black knight gets about 5-6' wide easily. If the container is 20 feet can't you space them out? Or did you mean to say 20 inches?

Hi Paul. Planting shrubs that close together may be very problematic most of the time, but we experimented last year and planted a Black Knight and a Honeycomb butterfly bush about a foot apart so we could intermingle the limbs to make it look like one plant with different colored blooms. They are both over my head this year and neither seems to be having any problems. Though it may be a different story inside a container but if the plants weren't that pricy I say give it a try. Butterfly Bushes are resilient and you can always transplant them if they don't respond well.

Of course it's only been 1 year but our dynamic duo are happy and healthy so far. They're planted at my mom's house and probably started blooming this week. Can't wait to see them this weekend.

Happy gardening. Sincerely, Danielle

Sorry about that, my mistake....I meant 20 inches.....but I kinda had the same idea as Danielle mentioned, having the limbs intermingle etc....I did get these plants at a good bargin I thought, $4.57 a piece at Home Depot....I planted them yesterday so as you said I can translant them if they don't respond well....thanks to both of you for your feedback.

I also bought another 'Honeycomb' butterfly bush for another area....I sure like the smell and look of the flowers and it seems everything that flies in the air likes it too...

Paul