One of the great things about delphinium is that you can get a second set of blossoms if you treat the plants properly. I am getting a second show right now. Not as tall, but still glorious.
First blooms are always more dramatic (photo taken at Cider Hill Gardens, Windsor, VT)
Delphinium is one of the fussiest plants I grow, but they are also spectacular when in bloom. Tall blue or purple spikes can rise up 5 or 6 feet in the garden. Those flowers are glorious, but will topple and fall with the first sign of rain, unless they are properly staked. Generally I set a 4-foot steel rod or bamboo pole next to a delphinium spike and tie loose loops around the plant in two places.
Staking is important for delphinium. The wine cork on this iron rod is to protect me from getting poked in the eye while weeding.
How do I get a second bloom? The trick is to cut off the first flower spikes right after the blossoms have gone by. This year I did that in late June, cutting the stems off about 6 inches above the ground. Last year I cut the stems right at the soil line, and it did not stimulate new growth. In fact, my delphinium did not come back after the winter, though that might not have been the reason.
This re-bloom is shorter than the first bloom, but good for a vase.
At the time of cutting back the stems I scratched in a handful of Pro-Gro, the slow-release organic fertilizer I use. They need more fertilizer than most plants, probably because they expend so much energy to create those tall flower stalks.
If you did not cut off the flower spikes after blooming, do so now. It takes a lot of energy to make seeds, and you want your plants, especially first year plants, to focus now on growing roots. But next year, be sure to cut them off early.
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