Delphinium trolliifolium

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USDA Hardiness zone: Zn5b -10º to -15ºF

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Delphinium trolliifolium

Giant Larkspur or Cow Poison, I prefer the first common name for this stunning large growing native Delphinium. In vernally wet sites to moist upland sites  it forms large spectacular colonies. In late spring and early summer stems that soar to nearly 4′ tall are loosely decorated with marine blue flowers with a lighter central bee. In habitat its common associates are Oregon Ash (Fraxinus latifolius) and Oregon white oak (Quercus garryana) where it can be found in the shade of these deciduous trees. The one variable with this Delphinium is that it is found in cool places- never hot and dry. These shadowy environs can make this plant hard to spot even in full bloom.  Often they will be in standing water during the winter months and they are adapted to very heavy wet clay soils. In cultivation the need for moist conditions continues and it does appreciate at least an application of all organic fertilizer and compost at planting time. Keep it well watered through its bloom cycle, then it can go drier but never dust dry- in time it can handle much less irrigation. An annual mulch is beneficial. Wonderful, bold cut flower , but its loved by pollinators as well ( what is it about blue flowers? ). Forms spreading colonies in time. Give it room to stretch out. Its often found with our native Cow Parsnip (Hieracleum maximum) and great Camas ( Camassia leichtlinii) in habitat. This could easily be replicated in a garden. Native to the Willamette Valley into the Columbia River Gorge. Once widespread in the Willamette Valley its territory has shrunk precipitously. Long lived perennial. Very good deer resistance. Extremely showy in bloom.   Oregon native plant.

Delphinium trolliifolium

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