I have a Daphne bholua 'Jacqueline Postill' and it has suckers just underneath. When should I take the sucker up?
Leave it until just before spring, lift it out of the ground and sever it from the mother plant.
Make sure you take some soil with the sucker as the organisms in the soil play a major role in the survival of your new plant.
Mix the soil with compost and insert the sucker into the pot.
Water and keep in a glasshouse until the plant is strong enough to be planted outdoors.