By Paulr999
Leicestershire,
United Kingdom 
Knautia macedonica.
I planted 2 of these late season last year and this year they have gone mad. Starting from approx 6" high by 2" wide they are now about 5 foot wide by 3 foot tall. Plenty flowers of a lovely deep maroon colour but it does appear to ba a bit of a thuggish plant, pushing everything out of its way. My question is, will these continue to grow at the same rate and take over the garden or if I cut them back hard in autumn will they come back to the same size they are now ?
Im assuming they can be split in spring ?
Thanks in advance
22 Jul, 2011
Answers
My Knautia want to take over the world too! I cut them back hard a week ago, and they are already sprouting strongly. I love this plant, and found myself apologising whilst chopping them back!!
22 Jul, 2011
It's the same with the other genus in that group - Scabiosa, they too go beserk !!!
22 Jul, 2011
Thanks for the replies.
They are such a prolific flowering machine Im happy to dehead them for the moment with a view to cuting back hard later
22 Jul, 2011
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I've found they've got a few inches bigger each year, but that's just mine, here.
I'm going to split mine next spring, all the other perennials benefit from it - they grow a bit less tall.
Also, i've found that cutting the Knautia hard back in early summer helps - keeps it under control a bit !
22 Jul, 2011