help with Black Cohosh

Question

I planted 6 Black Cohosh roots this spring. Only 3 came up, much to my surprise. They are in a wet garden with a pH of 5. 5 and in the shade. The soil is very loamy and rich. My understanding is that these grow up to 20 inches a month. They’re all about 8 to 10 inches tall, look healthy but are not growing. What am I doing wrong?
Rolf

Answer 1

Scratch that. I did not see that you planted the rhizomes.

Ok, have you mulched them heavily after they came up? Once they start growing, they like to be heavily mulched with 3-5 inches of mulch. Make sure that they are getting enough water as well but that they are not in standing water.

Answer 2

Established plants may grow at that rate, but seedlings do not. Most Black Cohosh is grown from rhizomes rather than seeds. Rhizome grown plants are much faster to grow and mature. The plants grown from seeds can take up to 6 years before they are mature and large enough to have harvest-able roots. They just need more time is all.

Answer 3

Thank you Heather.
Yes they have been mulched with several inches of Preat moss, and more mixed into the soil.
They live in a "Bog" type garden with Lobelia cardinalis 'Gladys Lyndley.' and cardinal flower queen victoria and Ligularia stenocephala The Rocket .
Which are all doing fine. "The Rocket's" are stunning giants. The Black Cohosh were suposed to be in front of them as they are a foot or so shorter. Whith those pretty bottle brush white flowers and the Rocket's yellow bottle brush flowers behind.
Perhaps I just got a bunch of duds, and need to start over next spring, as only 3 of 6 even came up.

Thanks for your input.
Rolf