Heliotrope, Saint Fiacre’s herb

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Heliotrope (Heliotropium) forms a bright green bush of large dark blue flowers with a delicious vanilla-like fragrance, best placed beside a terrace where you pass close by. It freezes and dies below 25°F (-4°C), so grow it in pots as you would geraniums; bring them indoors in cold weather and this perennial returns each year.

It is perfect to adorn your flower beds, garden boxes and pot arrangements. Here is our advice on how to produce magnificent flowers for as long as possible.

Planting, sowing heliotrope

Heliotrope loves full sun and fears both cold weather and cool winds.

This plant will freeze and die whenever temperatures drop below 25°F (-4°C), so it should be grown in pots much as you would geraniums. This makes it easy to bring it indoors over winter.

• It is recommended to plant heliotropes bought in nursery pots in spring, after any risk of freezing is over.
• The soil must drain well and the stay quite cool all year round.
• Have a preference for garden earth blended with special flower plant or perennial plant soil mix: this will make your soil richer.
• Keep a distance of around 16 to 20 inches (30 to 40 cm) between plants.

Sowing heliotrope

Best sow under shelter in March-April.

Transplant once to nursery pots before putting them in place during the month of May.

• Water regularly but not too much, until and after the seeds have sprouted.

Which heliotrope to choose?

Garden centres and seed catalogues offer a handful of reliable heliotropes that differ mainly in height, flower colour and the strength of their vanilla scent. Use the table below to match a variety to your pots, beds or window boxes.

Pruning and caring for heliotrope

Remove wilted flowers regularly when you see them die off to trigger production of new flowers.

As for watering, it is useful to avoid wetting the leafage and to water during prolonged dry spells.

For pots, shorter intervals between watering sessions are needed because pot soil tends to dry up much faster.

• Pinch out the growing tips of young heliotrope plants once or twice while they are still small, as this encourages side branching and many more flowering heads instead of one leggy stem.
• Heliotrope wilts dramatically as soon as its compost dries out and usually revives after a thorough soaking, so growers are generally advised to keep the compost evenly moist rather than letting it dry repeatedly.
• Container-grown heliotrope exhausts the limited compost quickly, so give it a liquid feed for flowering plants through the growing period to keep the vanilla-scented blooms coming.
• Inspect the undersides of heliotrope leaves under glass for red spider mite, encouraged by warm dry air and causing fine mottling, and for whitefly, whose feeding leaves foliage sticky with honeydew.
• Cut potted heliotrope back by about a third before moving it under cover, then keep the compost barely moist in a bright frost-free spot until new growth appears.

Heliotrope year planner: what to do, and when

Heliotrope asks for very little, but each job has its moment. Here is what the article recommends, task by task, so you can see at a glance which stage you are at.

Follow this sequence and you will keep the display going from late spring right through to early autumn.

All there is to know about heliotrope

This perennial plant, usually grown as an annual, grows to form a bright green bush that bears large dark blue flowers.

It also goes by the name “Saint Fiacre’s herb”, after an Irish saint who was knowledgeable in herbs. It will grow just fine in flower beds, garden boxes and containers.

Place it next to a spot that is often used like a terrace to fully take advantage of its delicious vanilla-like fragrance.

• Read also: propagate your perennials through crown division