PENSTEMON SENSATION MIXED. A superb medium to tall variety for the border (60cm) producing a profusion of flowers over the summer through to the first frost. A hardy annual / half hardy perennial it will over-winter in warmer areas. Cultivation Advice PENSTEMON SENSATION MIXED Classed by the RHS as Perfect for pollinators Sow the seeds thinly from March under cover with warmth in fine seed grade compost, barely covering the seed. Germination best at 60F+. Once large enough to handle prick out to trays or single pots and grow on. Well established plants can be planted out to a sunny location after all danger of frost has passed. Season: Perennial. USDA Zones: 3 - 8. Height: 24 - 36 inches. Bloom Season: Early summer. Bloom Color: Mixed. Environment: Full sun. Soil Type: Well-drained, sandy, pH 6.8 - 7.2. Temperature: 55 - 65F. Average Germ Time: 21 - 42 days. Light Required: Yes.. Depth: 1/16 inch Moisture: Keep seeds moist until germination. Plant Spacing: 18 - 24 inches.