Can ‘Giant Feather Grass’ (Stipa gigantea) be propagated by division or by seed only? What are the requirements for successful propagation?
You can propagate Stipa either by division or by seed. According to the A-Z Encyclopedia of Plants and the AHS Plant Propagation books, both ways need to be done in the spring. Specifically, seeds should be sown in containers in a cold frame in spring. Divisions should be done from mid-spring to early summer.
Seeds should be sown when you can maintain a temperature of 59 degrees F. Most grass seed germinates in a week. Transplant seedlings one to a pot or cell as soon as they are large enough to handle. Transfer pots of established seedlings to a frost-free place to grow. Plant out in mid-spring.
Divisions – cut back the foliage for easier handling, then lift the clump. Shake loose soil from the roots or wash clean, to make it easier to separate them. Use a sharp knife to divide the clump into good-sized sections. Trim any overlong or damaged roots. The divisions can then be replanted in the garden.
I have also noticed that in my garden, Stipa usually reseeds itself and if you look carefully you may find some small seedlings already started, which you can transplant.