Pruning butterfly weed

I have a lovely butterfly weed (Asclepias tuberosa) that is getting ready to make flowers. Very healthy and charming plant. However, it is not a bush. It is a tall spike with no hint of secondary branches. Last year it was the same, only it got powdery mildew bad so I cut it to the ground. I thought it might sprout out as a bush, but again it is a tall spike, so tall I have staked it so it doesn't flop.
How can I encourage it to bush out?
Thanks!

 

What do the flowers look like?

 

They haven't opened yet but they will be clusters of bright orange flowers.

 

I know there is the common name Butterfly Bush or Butterfly Weed. The flowers on the later probably look something like this. At least the name you had was correct.




Butterfly Bush(Buddleja davidii) looks more like this below.




They can both look a little rangy if not kept up. The Buttrfly Bush looks more rangy and doesn't(at least from my experience) flower except once in spring. The Butterfly Weed flowers profuely, at least it did in the warm So-Cal climates. You need to weekly snip off the seed pods so that new flowers continue. The pods will get big and unactractive. You can also shape it into a fairly medium sized decent looking shrub. But you have to keep up on it. It is worth it though. When you clip it you'll notice it bleeds a bit like milkweed.

 

ok but if it's just a single stem growing strait up, how can I prune that?
If I snip off some leaves from the bottom might branches grow from the nodes?
When I said before "it is not a bush" I just meant this individual plant was choosing not to grow bushy, and I want to force it to grow like a bush and not a single vertical stem. I had some others (all grown from the same seed pack) last year that were starting to bush, but the blue birds dug them up before they got big. This is the only one that grew fast enough so the birds couldn't wreck it.

 

If it is an Asclepias the flowers come at the ends of the stems, there is nothing you can do to make it bushier-growing without interfering with the blooming.

 

True, but nothing happens over night. That's sometimes the fun and challenges of shaping and building when it comes to the landscape or garden.

 

Yeah the flowers will be at the end of the stalk. Best to prune in fall or spring? I'll try chopping it down again and see if that persuades it to fork out a little.

 

Do that and you will probably lose all of the bloom for this year. If you have a butterfly weed it is an herbaceous perennial that sends up one set of stems each spring, that blooms at the top when these have finished their development. These same stems are kept the whole season, without more being produced, and then die away in the fall, to not be replaced again until the following year.

 

I was asking if it should be pruned in spring, before it develops flower buds, or in fall, after blooming?

 

The plant is an herbaceous perennial so this year shoots will die away anyhow and you should cut them down late in fall.
At spring pinch the very top (1-2 cm) of a new shoot when is about 10-15 cm tall, it should branch. Or start a new, bushy plant by sowing several seeds close to each other in the same 10 cm in diameter pot and transplant it to the garden.

 

Thanks for the tip!

 

If you cut the stems off you will get more stems growing from the root, but it probably is true you will not get blossoms this year. However, I would guess that even though those stems will die back this year, I would bet you will get those extra stems (because of the pruning) to come back next year.