Hardiness: USDA Zone 3a: to -39.9 °C (-40 °F) USDA Zone 3b: to -37.2 °C (-35 °F) USDA Zone 4a: to -34.4 °C (-30 °F) USDA Zone 4b: to -31.6 °C (-25 °F) USDA Zone 5a: to -28.8 °C (-20 °F) USDA Zone 5b: to -26.1 °C (-15 °F) USDA Zone 6a: to -23.3 °C (-10 °F) USDA Zone 6b: to -20.5 °C (-5 °F) USDA Zone 7a: to -17.7 °C (0 °F) USDA Zone 7b: to -14.9 °C (5 °F) USDA Zone 8a: to -12.2 °C (10 °F) USDA Zone 8b: to -9.4 °C (15 °F)
For me, this plant is best the first year when it stays small and upright. Following years it gets taller and likes to flop. It seeds itself in different places, so I have let the new ones grow, and taken out the older ones. Blooms June -September in my garden.
My information says it is hardy in zones 3-10. Light aids germination of seeds.
On Nov 28, 2002, Weezingreens from Seward, AK (Zone 3b) wrote:
Spike Speedwell is a low to mid-height perennial of upright habit, mainly spreading by slowly creeping rootstocks. It is fast-growing with a long lifespan. The dense foliage has a fine texture, and the tiny blue-purple blooms develope on moderate spikes, lasting from summer until fall.
Native to Europe and Asia, it grows on rocky limestone hills and in grasslands. It is one of the most common veronicas grown in U.S. gardens. Spike speedwell prefers fertile, moist but well-drained soil. It is somewhat heat and drought. This is a naturalizing plant.
I am not sure what exact variety I have; however, it is the blue-violet color. Just one of these plants has attracted hummingbirds to my yard, and numerous bees - which is fantastic! I live in Sterling, VA and it has bloomed all summer long - and it is October and it is still going strong. I have it growing in a large container on a deck and it has done very well.
The variety I have has wider leaves with a more fringed appearance than those shown - any ideas on which variety this could be would be welcomed.
This plant has been said to grow in the following regions:
Montgomery, Alabama Bear Creek, Alaska Sterling, Alaska Prescott, Arizona Hesperia, California Knights Landing, California Paradise, California Kiowa, Colorado Ocean View, Delaware Pretty Bayou, Florida Braselton, Georgia Mount Prospect, Illinois Kirklin, Indiana Barbourville, Kentucky Hebron, Kentucky Prospect, Kentucky Grasonville, Maryland Foxborough, Massachusetts Spencer, Massachusetts Douglas, Michigan Mason, Michigan Pinconning, Michigan Arden Hills, Minnesota Florence, Mississippi Kansas City, Missouri Bigfork, Montana Scotch Plains, New Jersey Hannibal, New York Rochester, New York Asheville, North Carolina Columbus, Ohio Edmond, Oklahoma Portland, Oregon Mercer, Pennsylvania Warrior Run, Pennsylvania Clarksville, Tennessee Dallas, Texas Mckinney, Texas Salt Lake City, Utah Leesburg, Virginia Clearlake, Washington Kalama, Washington De Pere, Wisconsin