Can anyone advise whether I should be pruning my dianthus plants back fairly hard now they've finished flowering?
I bought them from Homebase last September and they flowered through the autumn, were deadheaded then flowered again this year (I've had a good 3+ months of flowering 
).
I've deadheaded the plants thoroughly and notice they're putting on quite a lot of new, bright-green leafy growth around their base. It looks very healthy. The older growth by contrast is a darker grey-green and quite straggly. It looked fine with flowers on it but not so much now 
I don't want to jeopardise the new growth but I'd quite like to lop the older stems off. I'm hopeful that I might get a repeat flowering this September 