Just a couple more thoughts about selecting plants: looking only at plant hardiness zones will not give you best results for plant selection. The average annual minimum temperatures for even the highest parts of our area are above -30 degrees F. putting us in zone 4. Wind, aridity, ultraviolet rays, and soil conditions put us generally at more like zones 2 to 4 but even selecting only zone 2 plants is not the whole solution.
Most important in selecting plants, within cold tolerance range, is their adaptability to soil type and moisture. Within that range of plants seed source is extremely important. A plant from a mild climate source may die before it adapts, while a plant from a northern or mountain source will flourish. Where you plant in your yard and/or how the plant is planted ultimately may be critical factors in the success or failure of even a biologically correct plant. We will help you with these considerations.
Delphinium spp. Ht 12-48 in, Spd 12-24 in. Full sun, low to moderate water needs. Long flower spikes typically bloom from spring to mid summer. Several cultivars are available and offer blues and multi-colored flowers. Delphiniums are great in any garden.