One of the most beguiling scents in the summer garden, heliotrope sends out a hypnotic fragrance that will lure guests, including some of the winged variety, in for a visit. Butterflies love the sweet scent and rich purple flush of blossoms that mound atop stems covered with deeply veined, mint-like leaves. You will want to grow this summer annual in beds or pots near your favorite outdoor haunts.
Choose a site in full sun. Avoid locations where water pools as poor drainage is not healthy for annual plants. Heliotropes prefer rich soil and will spread out rapidly if happy in their location.
Prepare soil in the spring after all danger of frost is past. Add 2 to 3 inches of organic matter to the soil and cultivate to a depth of up to 10 inches to improve drainage and add nutrients. Add 1 lb. balanced fertilizer over 100 square feet of garden bed, and mix well to further enrich the soil.
Plant heliotrope as deep as it sits in the purchased container. Loosen the root ball gently by squeezing the sides of the container, and slide the root ball out into your hand. Separate compacted roots. Gently plant and firm the soil around the surface. Allow 12 inches between plants.
Water well after planting, and keep soil moist especially during the hottest days of summer. According to the Michigan State University Extension, withholding water from heliotropes may increase morning and evening fragrance. If the highest level of scent is your goal, water just enough to keep them from wilting.
Pinch back new growth up to three times in the first weeks after planting to produce a bushier plant with more blooms.
Fertilize heliotropes with a liquid mix six to eight weeks after planting to promote blooms and healthy growth. Always apply liquid fertilizers to moist soil.