I am wondering if the following plants can be divided or propagated successfully: Heuchera, Donkey Tail Spurge (Euphorbia), Corsican Hellebore, and Helianthemum.
I consulted The American Horticultural Society Plant Propagation book,
edited by Alan Toogood (DK Publishing, 1999), and it says the following:
- Heuchera: by division or by seed in spring. Since cultivars may not
come true from seed, I would recommend dividing your plants. Once spring
growth has begun, lift the plant from the ground and remove small
sections from around the edge (look for good roots, and 2-3 shoots). - Euphorbia myrsinites: (Just a note: based on the USDA information that
this plant is invasive in Oregon and banned in Colorado, I would think twice before propagating it. This species does a fine job of propagating itself, apparently. In general, the genus Euphorbia can be propagated by division in early
spring, or from spring to summer, by seeds in fall or spring, and by cuttings in summer or fall, but if you were to propagate by cuttings, you would need to protect your skin from the sap. - Helleborus argutifolius can be propagated by division after flowering,
or by seeds in summer. Test seed capsules for readiness by gently
squeezing. If the seed capsule splits to reveal dark seeds, it is ready
for harvest. Wear gloves! H. argutifolius (Corsican hellebore) often
self-seeds. Check around the base of the plant in spring. When each
seedling has at least one true leaf, gently lift and transplant to moist,
fertile soil in light shade. - Helianthemum can be started from greenwood cuttings rooted in summer
and fall, and by seeds sown in spring in a frost-free location.
If you would like further information on the relative ease or difficulty
of each of these methods for each of these plants, I recommend coming to
the Miller Library and looking at our books and other resources on
propagation. Here is a link to a booklist.