Salvia is a group of perennial and annual plants in the mint family, grown for upright spikes of tubular flowers in blue, purple, pink, or red. Perennial types like Salvia nemorosa are reliable in Zone 6b and attract bees and hummingbirds while tolerating heat and drought once established.
Most ornamental salvias bloom in early summer and rebloom if cut back after the first flush. They need full sun and good drainage; wet, heavy soil in winter is the main cause of plant loss. Established clumps benefit from division every three to four years.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.
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.
Downy mildew
Yellowing on top of leaves with grey-purple fuzz underneath. Spreads rapidly in humid conditions.
Remove affected leaves. Improve air circulation. Avoid overhead watering. Copper spray as preventive.