Dark Opal Basil seeds produce one of the most visually striking sweet basil varieties available to home gardeners — a deeply pigmented, jewel-toned herb with broad, glossy leaves ranging from rich burgundy to near-black purple. First developed in the 1950s and awarded an All-America Selections honor in 1962, this open-pollinated variety brings genuine ornamental drama alongside the warm, clove-tinged sweetness characteristic of classic Italian basil. The dark foliage is caused by high levels of anthocyanins, the same pigments found in blueberries and red cabbage, giving it a nutritional edge alongside its beauty.

Growing Guide

Dark Opal Basil reaches maturity in approximately 60 to 70 days from transplant. It is a warm-season annual that thrives in full sun — a minimum of six to eight hours of direct light per day keeps foliage richly pigmented and growth vigorous. Start seeds indoors 4 to 6 weeks before your last frost date, sowing just 1/4 inch deep in a warm, well-draining seed-starting mix. Germination is best at soil temperatures between 65°F and 75°F, typically occurring within 7 to 14 days. Transplant outdoors only once nighttime temperatures consistently stay above 50°F, as cold stress causes leaf blackening and stunted growth. Space plants 12 to 18 inches apart in rich, moisture-retentive but well-drained soil with a slightly acidic to neutral pH of 6.0 to 7.0. Pinch flower buds as they appear to extend the harvest season and encourage bushy, full growth. Difficulty level: beginner-friendly with proper warmth.

Harvest & Use

Begin harvesting once plants have established at least four to six sets of leaves, cutting or pinching stems just above a leaf node to encourage branching. Regular harvesting every one to two weeks prevents the plant from bolting. The flavour is distinctly sweet basil with deeper, spicier, almost clove-like and slightly anise-forward notes compared to Genovese types — a complexity that pairs well with tomatoes, stone fruits, soft cheeses, and vinaigrettes. Infuse white wine vinegar with the leaves to produce a stunning deep rose-pink herbal vinegar, one of its most celebrated culinary applications. The leaves also make a vivid addition to summer salads, pesto blends, and cocktail garnishes. For short-term storage, keep cut stems in a glass of water at room temperature away from direct light; refrigeration causes blackening. Dry or freeze leaves for longer preservation.

A reliable, award-winning basil that earns its place in both the kitchen garden and the ornamental border with equal confidence.