delphinium 'blue butterflies' (55854 bytes)

Delphinium: The Diva of the Colorado Garden

By Terry Deem-Reilly, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver

What’s not to like about delphinium? It’s tall (great for the back of the border), it's showy (all those blossoms!), it's even thatblue delphinium (27157 bytes) hardest-to-find color, true blue (if you're not tempted by the mauve, pink, white, or lavender varieties).white delphinium (25274 bytes) It even thrives in our alkaline soil. So why do so many Colorado gardeners wince at the idea of growing it?

Well. for one, it's one of the needest perennials ever. It likes sun but not in the hottest part of the day. It needs even moisture, mulching and careful watering.  It reacts poorly to extremes of heat and cold, and requires a lot of fertilizer. To top all thatdelphinium 'summer skies' (26636 bytes) off, it requires its devoted fans to cut it back immediately  after  early-summer flowering before it will even consider reblooming a full three months later. (Many years, early June bloom is all you get, given the extreme pickiness of this flower.) Finally, unless it really, REALLY likes its location, it may never be seen again after that September curtain call.

Considering all this, growing delphinium seems  hopeless in Colorado. There are, however, some techniques that can improve the odds:

  • First of all, recognize that delphinium is identical in one respect to a normal American teenager, i.e., it requires continual feedings. Plant only in compost-enriched, well-drained soil and fertilize so it's well and regularly nourished.

  • Don't let the plants dry out. Keep soil evenly moist even and roots cool by mulching to a depth of 3" or 4", either with a good organic mulch or with compost. Water well during periods of growth (in spring and after it begins its second season's growth).

  • Plant it in areas where it gets some shade during summer afternoons.

  • Overwinter by covering the plants with branches or  mulch to protect the roots from frost heaving.

  • Choose varieties like D. exaltum or D. belladonna ('Connecticut Yankees') that cope well with extremes of temperature. A short variety, 'Blue Butterfly' (see top of page), grows well in the West and even reblooms without being cut back! It's available from High Country Gardens in Santa Fe.

If the above care fails and delphinium is still your favorite, don't despair - just start indoors in late winter in peat pots and grow it as an annual. Who knows, it may decide to reward your devotion by returning all by its lonesome....or maybe not.

A good source for information on delphinium (including a map of the best parts of North America for growing it) is Dowdeswell's Delphiniums.

 

Photos: Judy Sedbrook

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Date last revised: 01/05/2010