Voluptuous, regal purple flowers and a unique perfume make this an old favourite.
It is confession time again – this is not an annual. But, if it is grown at all, it is either grown as a summer patio plant and discarded in autumn or it is grown as an annual. In fact it is a shame that the perennial kinds are rarely seen these days, replaced almost entirely by annual kinds such as ‘Marine’ and ‘Mini Marine’. When I was a student we grew heliotropes such as ‘Chatsworth’ as perennials, training them into standards and columns as ‘dot’ plants. Heliotropes have alternate, rather rough, dark green leaves and clusters of small, tubular flowers. The common name is cherry pie and the wonderful fragrance is sweet and like a cherry pie with hints of vanilla. There is nothing quite like it. In fact there are hundreds of different heliotropium species, from around the world, but the Peruvian H. arborescens is what we are talking about here.
The big plant breeders have not ignored this plant and the vegetatively propagated ‘Scentropia’ (pic above) is a low, spreading plant. ‘Marine’ grows to about 25cm high in a season while the old, perennial kinds can reach a metre or more. If I get the chance to buy an old variety I will do so, partly because of the chance to grow a large plant but also because most have an even better fragrance than the modern kinds. They are frost tender and must be kept above 4c at all times. Old, woody plants can stand more cold than young plants.
From seed, you need to sow as early as possible – I would start in early March – but you need to give seedlings good light and never ever let them be cold and wet. I would add extra perlite to the compost for super – safe drainage. Plants are very slow to get going when small but once the sun starts to rise in the sky in April they get a spurt of growth. Small plants produce their first, terminal flower cluster and then start to branch. In theory I suppose the first flower cluster could be removed to encourage branching but I am always in too much hurry to see, and sniff, the flowers.
I would never bed out with heliotrope, they are rather too special and deserve a place in patio pots where it is often more sheltered and warmer, which will help growth and also help to appreciate the perfume more. Heliotrope always looks good with silver foliage but more traditional flowers, especially in pink, such as petunias and diascias looks good too. Heliotrope is also loved by those most discriminating of pollinators, colourful butterflies.