QI bought a packet of delphinium seeds last spring and sowed half of them indoors in April. No plants came up. I sowed the rest in my garden in late June. None grew. Did I do something wrong? Was it bad seed?
ADelphiniums are treasured for their towering spires of blue flowers and can make a wonderful addition to the perennial garden. Many named cultivars are available as plants at nurseries and garden centers. Delphiniums can also be grown from seeds, but they can be a little bit fussy about conditions for good germination.
Using fresh seed increase chances of germination. You may have received old seed, though most reputable seed companies sell only seed that has a good germination rate. Once you receive a packet of seeds, it's important to store the seeds in cool dry conditions. I keep seed packets in airtight glass jars that I store in my refrigerator. This increases the longevity of any seeds.
Before sowing delphinium seeds indoors, put them in your freezer for 24 hours. Then sow the seeds in flats of moist, well-drained media. I prefer soilless peat-perlite-vermiculite mixes such as Pro-Mix or Jiffy Mix. Press the seeds into the surface of the media, but don't cover them; they need light in order to germinate. Keep the media moist and in a cool place, about 55-60 degrees. High soil temperatures can prevent delphinium seeds from germinating.
Once the seeds germinate, continue to grow them in a cool area with good light, such as fluorescent or in a sunny-bright window. It may take as long as two to three weeks for the seeds to germinate, so don't give up and throw them out if they don't come up right away.
You can also try sowing the seeds directly outdoors in late summer. Freeze the seeds for 24 hours prior to sowing them in a well-prepared seedbed. Keep the soil moist at all times. You may also want to shade the soil to keep it cooler. The young plants should stay in the seedbed through the winter. (Apply a winter mulch after the ground freezes.) The plants can be moved to their permanent location the following spring or summer.
QI would like to try forcing some flowers indoors. I have a forsythia and a crabapple in my yard. Will these work for forcing? How do I go about it?
AThe flower buds of some trees and shrubs can be forced to bloom indoors in the mid-to late winter. Only plant species that have well-developed flower buds that were set in the fall will work for winter forcing. Most of these plants bloom in early spring.
Forsythia is a classic for winter forcing. It is fairly easy to get cut branches of forsythia to bloom, and their bright yellow flowers are a cheery harbinger of spring. There are only a few forsythia cultivars that are reliably hardy in Minnesota, and even these can suffer flower bud damage in severe winters. However, this relatively mild winter has left the forsythia buds in good shape this year. 'Northern Sun,' 'Meadowlark' and 'Northern Gold' are the best choices for this area.
I've had less luck with apples and crabapples, though they may work. White forsythia (Abeliophyllum distichum) is less well known but also blooms profusely in early spring and is good for forcing. Cherries (including Nanking cherry), plums and apricots can usually be forced. Red maples have small but colorful flower clusters that also can be forced into bloom.
When forcing flower buds to bloom, carefully select branches to cut. Remember that you are pruning the tree by removing branches for forcing. Place the cut branches in a bucket of lukewarm water. Keep the bucket of branches in a cool, humid area, away from direct sunlight and heating vents. Place a clear plastic bag over the branches to keep the humidity high. If the flower buds dry out they will not open. Change the water in the bucket every day or two. The flower buds should start to open within one to two weeks.
-- Nancy Rose is a research horticulturist at the Minnesota Landscape Arboretum. She spends her spare time gardening, inside or outside, depending on the weather. Please address gardening questions to her at the Minnesota Landscape Arboretum, P.O. Box 39, Chanhassen MN 55317. She will answer questions in this column only.