Advice on Google is -after flowering -but what if it doesn't stop??
I hope someone answers, because I want to know too!
Autumn or winter to give it a rest? It has a habit of exhausting itself otherwise
Other than dead heading I am sure you can't prune them hard, they don't regenerate from wood, maybe a light trim but wouldn't think it worth it Once they are out of shape I get rid.
By prune I just mean dead head the flowers worth taking cuttings, they aren't long lived perennials
I'm onto my second batch. The first ones grew like fury and never stopped flowering eventually the plants grew too far over a garden path..so I cut them back pretty hard..lesson learnt they never recovered and died. Luckily I'd taken cuttings, they are now very mature, you can dead head at any time but the plants age from the roots up and get very woody. I'd hang on until spring, take cuttings, and gently cut back or scrap the original plant.
How do you take cuttings from this plant? Mine is quite woody, so probably won't get that much longer out of it!
I take mine in spring so I'm keeping the Mammy plant going for a few weeks more. I just snip off shoots about 4 inches 10cm long. Strip of bottom leaves and plant say 3 or 4 cuttings in a small pot filled with multipurpose compost or multipurpose half and half with fine grit or vermiculite if you have it. Water not to heavily drain then pop it into a poly bag, either ziplock or those ones you get in a supermarket fruit dept that tie. I pop a skewer in to keep the plastic off the leaves. You could use a cut down soft drink bottle as a mini cloche. Keep in a bright spot on a window sill but not in sun. Well that my method and it works for me.