Spike speedwell is a flowering perennial plant that is also known as Veronica spicata. It grows to 2 feet tall and requires little maintenance besides a bit of pinching and pruning to keep it compact and bushy and flowering all summer. It's well suited to USDA climate zones 3 to 8 (Minnesota to Florida) in sunny locations with sandy or loamy clay soil.
Deadhead spent flowers by cutting them off at their base after they bloom. This will encourage the plant to continue producing more flowers.
Pinch spike speedwell back in late spring by removing the growing tips and first set of leaves. You can use your fingernails for this task, but be sure to pinch it off above a node, where a branch or leaf emerges. Pinching in this manner helps the plant to remain bushy and encourages new growth on which flowers will form.
Cut spike speedwell back to its basal foliage in October or November, removing all tall flower spikes down to their base and leaving just the bottom leaves of the plant. If you apply a layer of compost, wood chips, sawdust or other mulch at this time, it will help protect the plant against cold winter temperatures.
Prune the root system of this plant in spring or fall when it creates a large clump. Dig it up, divide the root system into several chunks, cut off all dead roots and trim all roots into a compact ball shape. Pruning the roots of perennials will stimulate new growth. Replant each chunk about 1 foot from each other.