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The heliotrope flower (Heliotropium) is a genus of flowering plants in the Boraginaceae family with about 325 species. They are popular and stunning flowering perennials thanks to their aromatic and delicate blooms in the old cottage garden style. Heliotrope flowers are tiny flowers that grow in clusters that follow the sun, which led to their name, which is directly derived from the Greek words helios (meaning “sun”) and tropos (meaning “to turn”). Some gardeners describe the scent of the flowers as vanilla, while others insist they smell like cherry pie. Plant fast-growing heliotropes outdoors in spring after the danger of frost has passed. This plant is poisonous to humans and animals.1 Learn how to grow these attractive, delicate perennials in your garden.
Heliotropes are temperate perennials native to the subtropical regions of Peru. Outside of their native range, heliotropes are usually grown as annuals because they are half-hardy and very frost-tender. They are considered low- to medium-care plants that benefit from some regular care.
Heliotropes are full-sun plants, requiring at least six hours of direct sunlight per day. However, they prefer morning sun, and in hot climates, intense afternoon rays can burn the delicate flowers. A location that receives bright morning sunlight and light afternoon shade is ideal.
Plant heliotropes in rich, loamy soil that drains well but retains some moisture. They prefer soil that is rich in organic matter and has a pH between 6.6 and 7.3. Heliotropes do not do well in heavy clay soils because they do not tolerate wet feet.
Heliotropes require a lot of water to thrive. Keep the soil evenly moist but not soggy, and don’t let the plants dry out. When grown in containers, heliotropes will need to be watered significantly more frequently because the plant will absorb the water more quickly.
Heliotropes grow best in climates with warm days and cool nights. They don’t do well in excessively hot or humid weather and are very sensitive to frost.
Heliotropes are known to be very feeders and need to be fertilized regularly throughout the growing season. When grown in the garden, heliotropes should be fertilized at least once a month. When grown in containers, they should be fertilized up to every two weeks. Use a high-phosphorus fertilizer designed for flowering plants. Follow the product label directions for the amount to use.
‘Princess Marina’ (Heliotropium arborescens): This is a compact heliotrope, but the typical cherry-pie-scented version with violet-purple flowers, growing only 6 to 12 inches tall.
Cradling heliotrope (Heliotropium amplexicaule): Also known as blue or summer heliotrope, this plant produces tiny, bright purple flower spikes that attract pollinators.
Beach heliotrope (Heliotropium anomalum): This pretty groundcover plant is a native Hawaiian plant with silvery-thin leaf spikes that produce fragrant white flower spikes.
Salt heliotrope (Heliotropium curassavicum): Also called beach heliotrope, this aggressive plant thrives in wet or dry and salty soil and produces white flowers with yellow and purple throats.
Heliotropes can be propagated by cuttings or seed. To propagate from cuttings in spring or summer, follow these steps:
Take 4- to 5-inch-long cuttings from a fleshy, green heliotrope plant outdoors.
Remove the leaves from the bottom half of the cutting and dip it in rooting hormone.
Place the cutting in a pot of moistened soil.
Place the pot on a windowsill with bright, indirect light. Avoid direct sunlight, or the young plant may burn as it takes root.
Keep the cuttings moist.
After a few weeks, the cuttings should take root. Place the pots in brighter, more direct sunlight. Overwinter the cuttings indoors.
Transplant them outdoors or into a container garden in spring.
Growing heliotrope from seed may be the easiest and most popular way to grow these flowering perennials. Seeds should be sown indoors 10 to 12 weeks before the last frost. so that the plants have time to flower before the first frost in autumn. Heliotrope seeds should be kept at a temperature between 21 and 24 degrees Celsius and should germinate within 28 to 42 days. Once the last frost has passed, the heliotrope seedlings can be transplanted into the garden or into a container outdoors.
Heliotropes are perfect for pots because they are non-aggressive and won’t overgrow your container garden. They are also not susceptible to serious pests or diseases. Keep in mind that heliotropes in containers require significantly more water than plants grown in the garden.
If you grow heliotropes in containers, you can easily overwinter them indoors if necessary. Bring the plant indoors before the first frost. Place it on a windowsill in a cool room with bright, indirect sunlight that won’t burn the plant. Water in small amounts so the plant doesn’t dry out. Don’t place the plants near a heat source, as this will result in dry soil. Bring them back outside in the spring when temperatures consistently rise above 13 degrees Celsius.
Watch for aphids, mealybugs, spider mites, fungus gnats and whiteflies, all of which can be treated with insecticidal soap or neem oil to eliminate infestations. Although the plant is not susceptible to many diseases, you should watch for fungal infections such as powdery mildew, which occur in poor air circulation and very warm soil conditions.
Regularly pinching and removing the spent flowers of your outdoor heliotrope plant will encourage more consistent blooming and bushier, denser growth. You can start pinching the stems and flowers in early spring to encourage more lateral growth. This may delay the first bloom, but you will be rewarded with larger and more lush blooms for the rest of the season. Indoors, heliotrope can have a harder time blooming, so make sure they are moist enough, fertilized and receive enough bright light.
Whether indoors or outdoors, heliotropes don’t cause too many problems. Watch for some rare problems.
Conditions may be favorable for powdery mildew. Remove damaged flowers to encourage more blooms. Water the soil so it doesn’t become bone dry, but don’t overwater.
A drooping heliotrope could be stressed because it’s getting too much sunlight or getting too much water. Although the plant prefers dry conditions, it doesn’t like being scorched, dried out, or mushy.
Check for spider mites. Spider mites suck moisture from the leaves. They can be identified by their white webs that form on the underside of the leaves. Sap-sucking whiteflies could be another problem and can be seen with the naked eye. If pests are present, use insecticidal soaps. Brown leaves can also mean that the plant is getting too much water.