I regularly take cuttings of Dianthus and I have had the same problem in a few cases. What works best for me is to grow them with bottom heat in a propagator and use hormone rooting powder. I would also recommend that as soon as they start to grow that you pinch the growing tips out.

Thanks, Jimmy. I thought I’d done something wrong even though I’ve taken loads of cuttings before. I had already pinched out the tops several weeks ago but I’ve just done it again. I guess my friends won’t be receiving them any time soon!