At its best:
Mar, Apr, May
Dig up your perennial oriental poppy when the plant is dormant - or almost - in late autumn or winter. Wash off the soil around the roots.
Choose strong, pencil-thick roots if possible, but if there aren't many that thick, then go for medium-sized or fibrous roots, as these will often root well.
Cut off a piece of root with a sharp knife, taking care to never remove more than one-third of the roots, as that would probably kill the plant.
Cut each root into sections measuring 5-10cm long - the thinner the root, the long you should make the cutting.
For thick roots, make a flat cut at the top of the cutting and an angled cut at the base, so you know which way up to insert them. If you put them in the wrong way up, they won't grow. Fibrous roots can be simply cut into sections. Treat the cuttings with fungicide to prevent rotting.
Fill 15cm pots with cuttings compost, then make five holes per pot to insert the cuttings.
Push one cutting into each hole, slanted end down, so that the flat top is level with the surface of the compost.
Top with a layer of horticultural grit to reduce the chances of rot. Label and place in a cold frame or cool greenhouse, and don't let the compost dry out. Shoots should appear in spring and, once well rooted, you can put up the cuttings individually in 8cm pots. Grow on until they're large enough to plant out.