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.
Veronica spp Ht 1-48 in, Spd 12-48 in. Full sun to part shade, low to moderate water needs. From low creepers to erect flowering stalks, there are several varieties available. Most flower in shades of blue, but white and pink are also choices. Veronica is generally easy to grow, thriving in very average soil conditions. Some varieties are xeric as well. Deadhead as soon as flowers begin to wilt to promote rebloom. Some varieties will peak out in June, while others will provide blossoms all summer long.