Chocolate mint is a peppermint cultivar with dark stems, chocolate-brown-tinged leaves and a scent that reads as a peppermint patty. It is used in desserts, hot chocolate, iced drinks and as a garnish. The flavour is more complex than standard peppermint, cooler and sweeter with a lingering cocoa note.
All the usual mint rules apply. Plant it in a container or a bed with a solid edge, because it spreads by runners as aggressively as any peppermint and will take over a border in two seasons. Give it rich, moist soil and sun to part shade; it tolerates more shade than most herbs. Harvest before it flowers, when the oils are strongest, and cut the whole plant back by half after the main flush to get a second one.
Like other peppermints it is sterile and does not come true from seed, so buy a plant or take a cutting; a stem in a glass of water roots in a week. Cut it to the ground in late fall. Deer leave it alone.
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.