I moved to New Hampshire from Missouri and want to grow lupines.
Having purchased some plants, I have enjoyed many blooms. After the
bloom, the flower turns into what looks like a pod with seeds. Can I
replant those seeds in order to propagate them for next year, or when is
the best time to plant them? Also for the remaining foliage on the
plant, what should I do to maintain it? Continue to water it and give it
MiracleGro for nutrients?
According to the American Horticultural Society’s Plant Propagation edited by Alan Toogood (DK Publishing, 1999), lupines may be propagated from seed between early and mid-spring. (Other methods of propagation
include stem cuttings taken in mid- to late spring). Lupine seeds
require some special treatment, as described by the Sustainable Urban Landscape Information Series (formerly available online from University of Minnesota):
“Moisture is important to seed germination. Some seeds are protected by a
tough seed coat. Some must be soaked in water to soften the seed coat
prior to germinating. Other seeds must have their seed coat nicked or
pierced (scarified) in order to allow moisture to reach the seed, causing
it to expand and break through the seed coat; two examples are in the
legume family – sweet peas (Lathyrus species) require soaking, and lupine
(Lupinus species) require scarification.
The following information from University of Washington should apply to
your lupines, not just our native lupines. It suggests collecting seed from June to August, storing the seed in the pods inside paper bags, and then scarifying them prior to soaking and sowing (in spring or fall).
Lupines should do well in zones 3 to 8, depending on the species. More
information on growing hybrid lupines can be found here, including
suggestions on fertilizing. Choose a complete slow-release organic fertilizer instead
of synthetic fertilizers like MiracleGro, which may be too high in nitrogen.
When flowering is finished, you can cut the plants down to the ground, and you
may still see a second burst of growth. There is no need to water when the plant
is not in active growth. (In our Northwest climate, the leaves tend to
look mildewy by this time of year, and you would want to cut them back
anyway). Rainyside Gardeners, a Pacific Northwest website, has additional information.