Minter: Move over, Hawaii. We've got hibiscus growing for late summer

The following column was submitted to the Tri-City News from Brian Minter — master gardener, best-selling author, Order of Canada recipient and co-owner of Minter Country Garden Store.

Move over Hawaii and Tahiti, we have our own beautiful hibiscus to light up our summer gardens.

Hardy Hibiscus syriacus, (shrub althea or Rose of Sharon) is, perhaps, one of the most under-used, summer-flowering shrubs. Cultivated in England since the 16th century, only recently has it become a more mainstream plant, and that’s because of today’s many new varieties.

Hardy to zone six, and possibly some high zone fives, it is one of the few flowering shrubs that opens in succession from July through to October. Once the hydrangeas finish, there is a distinct lack of flowering shrub colour in the garden, and that’s why these plants are so important. Hibiscus are generally the last flowering shrubs to show leaves in spring, but they more than make up for it by being the last hurrahs in the fall garden.

Hibiscus need a little care to get established. They require full sun or just a touch of shade and a little attention, especially in this heat, to get going and to perform their best. Hibiscus grow just fine in a wide variety of well-drained soils that contain plenty of organic matter to hold moisture. During periods of hot weather, they need a thorough, deep watering to keep those flower buds coming. Don’t move them around the garden as they are not happy being transplanted. It’s also a good idea to mulch their roots during the first couple of winters to protect them from deep frost.

Hibiscus are small to medium sized trees, usually sold in bush form, but they can also be purchased or trained into a handsome tree form. Growing about 3.5 meters (12 feet) in height, they can easily be pruned in late winter to conform their size to your garden space.

There are three flower forms: large singles, semi-doubles and smaller doubles. My favourite is ‘Red Heart’, a large white single with a red eye that really shows up in the garden. ‘Diana’ is a huge, pure white triploid that remains open at night. ‘Minerva’, a large lavender, is most people’s favourite. ‘Woodbridge’ is a single magenta rose with a red eye. ‘Bluebird’ and ‘Marina’ are improved forms of a single blue with a red eye. In the double forms, ‘Ardens’ is a purple and ‘Collie Mullens’ is a magenta rose with a crimson eye.

‘Chiffon’, a Proven Winners series, features beautiful, large, full, semi-double blossoms. The blue, lavender, white and pink ‘Chiffons’ are quite spectacular. Innovative growers are now planting two colours together in one container, providing a stunning, two-tone effect for a unique addition to any garden. The real novelty, however, is the first columnar form called ‘Purple Pillar’. As the name suggests, its growth pattern is a narrow column, allowing it to fit nicely into smaller spaces. ‘White Pillar’ is the newest introduction, and it’s spectacular.

There’s also a new, very compact series, called ‘Lil’ Kim’, which acts more like a low flowering shrub.

Hibiscus are blooming now in most garden stores, and it’s a great time to see all the varieties to make a choice for your garden. Planted now, they will light up your summer garden for years to come.