I love plants that do wonderful things at unexpected times of the year. Osmanthus is just such a plant, producing clusters of intensely fragrant flowers in late autumn – usually October and into November, when the rest of the garden is winding down for the season.They’re such great plants that I just can’t figure out why more people don’t plant them!
Also known as sweet olive (O. fragrans ) or sweet holly (O. heterophyllus ), Osmanthus is in fact in the olive family. And while one of the more fragrant species – O. fragrans – can suffer in our most bitter cold spells (sort of like real olive trees can suffer when young), the other species are very tough and cold-hardy. Not to discourage anyone from trying the sweet olive: once it’s established, it can survive just about any cold the Portland area can dish out. For proof, just visit the Lan Su (Classical Chinese Garden) in the next week and you’ll might find yourself swooning as you wander near the Garden’s Osmanthus fragrans ‘Aurantiacus’ – the orange-flowered sweet olive – which is currently encrusted with tiny, headily fragrant, apricot colored and scented flowers. About twenty feet to the north of it is another species that looks to me like Osmanthus decorus (also fragrant).
The Garden actually has several other species of sweet olive. In the entryway garden is one of the most magnificent of them all: a white-variegated Osmanthus heterophyllus ‘Variegata’ – an ancient specimen (about 20′ × 20′) culled from a Portland neighborhood shortly before the Garden opened. I seem to remember the Garden also containing a specimen of Osmanthus heterophyllus ‘Sasaba’ – a very spiny, poky-looking, slow-growing species with rich, dark green foliage.
In addition to being wonderfully fragrant, Osmanthus are easy-care plants. They are moderately drought-tolerant when established and enjoy full sun but tolerate a half-day of shade, and there’s enough diversity among cultivars and species that you can find one for nearly any garden use you may have.
Osmanthus heterophyllus is a hardy broadleaf evergreen which can be grown as a pruned or unpruned hedge. Left to its own devices, it will become a 15-20 foot-tall and wide tree. Cultivars abound: there’s the white-variegated Variegata; the warm yellow-variegated Aureovariegata; and the purple-tipped Purpureus, all of which can reach about 12-15 feet over 20+ years and, eventually, can reach 20’ tall and wide. There are smaller cultivars, too: Sasaba, the prickly shortie with a very architectural look; Goshiki, a gold-and-green-variegated ball reaching about 4 feet in 10-15 years; and Gulftide, to about 10-12 feet, with spiny margined leaves. I am also fond of the cultivar Rotundifolius, with soft, non-spiny foliage and attractive burgundy-rust new growth. It is more slow-growing than the species and seems to reach about 6 feet in ten years. And best of all, I just saw an exquisite gold-leafed cultivar called Ogon for sale at the Garden in one gallon pot.
Osmanthus fragrans is usually seen with white flowers, but the form Aurantiacus has lovely apricot colored flowers.
Another fall-blooming species is O. decorus, a small, tidy tree with white flowers and smooth leaves resembling those of the bay tree. The tree reaches about 12 feet in ten years.
But there are a few spring-flowering Osmanthus as well: O. delavayi is a 15-20’ tree in time, with small leaves and lots of little white tubular flowers and is a parent to O. x burkwoodii, a bi-generic cross between O. delavayi and Phillyrea vilmoriana and reaches about the same size or a bit bigger, with larger leaves.
The spring-bloomers are nice enough, but the it’s the surprise of the fall-flowering sweet olives that really does it for me. Visit them in the next week at the Lan Su Garden and imagine having that fragrance and beauty in your own garden!