How do you divide and replant poppies? The oriental poppies have become quite large.
Can I also cut them in half and remove one section, leaving the other in the ground, undisturbed? Will this affect the symmetry?
Thank you for contacting the Toronto Master Gardeners. Oriental poppies (Papaver orientale) have a very long and large taproot, and for this reason they resent being divided so it should be avoided if possible. They are best propagated by taking root cuttings. However if your clump is very large you could perhaps try slicing off a very deep section at the edge of the clump and transplant it to a site that has been properly prepared for a new planting.
The preferred option is to take root cuttings. This is not difficult and you can get multiple plants with this approach. The plant should be dormant – P. orientale goes dormant after it has flowered in the spring and the leaves have turned brown. Ideally you would dig up the entire plant to expose the roots, but since yours is so large you can rake the soil away from the crown to expose the fleshy roots. Cut sections of healthy roots, about 5-10 cm long and about pencil thickness. Plant these root cuttings horizontally in pots with a light potting soil, about 1-2 cm deep and then covered with soil (or you can try planting them directly in the ground about 1-2 cm deep). If you plant them in pots, cover the pots with a plastic bag and put them in a sheltered bright but not sunny spot. Shoots should emerge in a few weeks but keep them covered with a plastic bag to give the roots a chance to develop. Then gradually harden them off so they get used to their new environment, then plant them in their permanent home. P. orientale is quite hardy, but mulch around the new plants in November to provide some winter protection. They might not flower for a year or two.
Here are a few links with more information about taking root cuttings :
Good luck with your poppies !