SEATTLE — Few flowering perennials can match the elegance and beauty of Delphinium. Although there are varieties that grow to anywhere from 2 to 6 feet tall, the queen of this royal family of plants has to be Delphinium elatum. These gorgeous plants produce 6 foot tall, towering racemes packed with brilliantly colored blossoms that re highly attractive to hummingbirds and butterflies and vary in color from blue, purple, red, yellow, or white. Despite their regal charm due to over breeding of similar strains, many northwest gardeners gave up on growing the tall growing Delphiniums because the plants available lacked vigor, were susceptible to powdery mildew, broke easily in storms and rarely survived for more than one season.
It's time to give these gorgeous plants another try. Thanks to new breeding program, new much more resilient Delphiniums are becoming available at local and on-line nurseries. Delphiniums are now reliably perennial, highly resistant to powdery mildew, and produce sturdy flower spikes. There are quite a number of hybrids available, but my all time favorite is Delphinium elatum 'Cobalt Dreams' This is the bluest of any flower I've ever grown, featuring gigantic over 6 foot tall stalks crammed with extra-large flowers centered in white. Pure blue 'Black Night' is a close second, while ‘Royal Aspirations’ is a close third with similar stalks filled with big royal blue blossoms centered in black.
Even the much improved strains of Delphinium need care in order to make sure they perform at the best in your garden. The trick to getting them to come back every year, not to mention getting them to bloom magnificently at least twice per season, is to never let them dry out. When you plant your Delphinium incorporate large amounts of organic compost. Mulch over the root zone to slow evaporation, and water as often as necessary to make sure the soil remains slightly moist at all times. Delphiniums are also big feeders. Work in a couple of cups of alfalfa meal with a cup of organic flower food into the soil around the root zone every 6 weeks beginning in early April.
Delphiniums die-back after they bloom. As soon as the first flush of flowers fade, cut the flower stalks back to lateral buds immediately below the spent flower. The secondary flowering branches will be much smaller and less showy, but make colorful additions in flower arrangements. After the secondary flowering is complete, the branches will begin to die back. Cut all of the stems down to newly developing basil foliage at ground level. Keep the soil moist, and continue to feed regularly and your Delphinium will quickly grow back and re-bloom again in late summer. After the second bloom ends, cut the stalks down and cover the stems with about an inch of compost. Your Delphinium will return to put on a magnificent show again next spring.
The biggest problem with growing Delphinium elatum is figuring out how to stake them. Even the newer sturdier strains of Delphinium are subject to wind damage. Avoid planting these titans in a windy location, even if you stake them well, strong wind can break the stem at the point where it's held up by the stake. In my opinion, the best system are the circular grid supports available at local nurseries.. This staking system consist of a circular wire ring filled with a pattern of cross wires. Metal supports inserted into the ground hold the ring in place a couple of feet above the ground. The secret to success is to use two rings at varying heights. Center the rings directly above the crown and set the system up early enough in spring to allow the stems grow up through the grid. Once the stems grow through, the grid does a great job of holding the stems upright. Prune out any stems that grow outside the circle. Only a fairly ferocious wind storm will cause the clump to fall over or break the flowering stalks. Best of all, once the stems grow through it, the foliage totally hides the staking system. Don't make the mistake I did one year by leaving the staking systems out in the garden after the season ends in fall. I'm still searching for some of the support rods that are hiding in the garden after I left out there 2 years ago!
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Segment Producer Suzie Wiley. Watch New Day Northwest at 11 a.m. weekdays on KING 5 and streaming live on KING5.com. Contact New Day.