Snapdragon is a short-lived perennial grown as an annual in Zone 6b. It produces upright spikes of tubular flowers in most colors except true blue, and is valued for cool-season bloom and long vase life. The flowers open from the bottom of the spike upward.
Snapdragons prefer cool weather and often slow or stop blooming during midsummer heat. Start seed indoors 8–10 weeks before last frost; seed needs light to germinate, so press it onto the surface without covering. Pinch young plants to encourage branching, and cut plants back after the first flush to trigger a second bloom in fall.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.