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Minter: Summer flowering perennial hibiscuses

Master gardener Brian Minter shares one secret to creating a "wow factor in any hot summer garden."
brianminterhibiscusperennialaugust2024
Giant flowering perennial hibiscus can be a creative addition to any summer garden.

There’s a great colour lift available at this time of the year that can make a real difference in our August and September gardens.

Giant flowering perennial hibiscus will certainly create a wow factor in any hot summer garden. 

Beginning about 12 years ago, seedling varieties of summer-flowering hibiscus, called the Luna Series, added a new look to summer gardens. 

Today, these seedling varieties have improved with the introduction of the "Disco Belle" and "Honeymoon" varieties. Both have a wider range of colours and blooms that grow from six to eight inches in size.

Walters Gardens in Michigan have introduced their own series of bicoloured and ruffled hibiscus, as well as many with rich burgundy and variegated foliage.

They also produce Proven Winners spectacular "Summerific" collection of outstanding varieties, such as the bicoloured soft pink and white "Ballet Slippers," the rich pink and red centred "Cherry Choco Latte" and the brilliant red "Holy Grail" with its contrasting dark foliage. There are so many great varieties available today that it’s hard to keep up.

It takes up to five months to grow a bareroot starter and requires constant care to keep it pinched back in order to create a full, well-branched plant, but the effort is well worthwhile, especially when the first giant blooms appear.

Last year, I happened upon a neighbourhood where many folks, over the years, had planted a significant number of these giants, and seeing a wide collection of so many of these amazing plants in a relatively small area was simply stunning.

There were many other beautiful perennials in these gardens but these plantings of hibiscus were over the top.

Once established, perennial hibiscus are both heat and drought tolerant. Last winter was exceptionally cold, but these zone four plants made it through nicely, especially when they were growing in well-draining soil.

They require little care other than refreshing the soil with applications of organic matter, like Sea Soil, and some slow-release fertilizer, like 14-14-14.

These showstoppers can grow up to 1.5 metres tall and wide, but most will grow in the 1 to 1.2 meters range. The more they become established, the longer they bloom, often going into late September and beyond.

At the end of the season, once the leaves have died down, they should be pruned back to about 20 centimetres above the ground.

Don’t panic in late May when they still show no signs of new life. Their life cycle begins sometime in June when they suddenly explode into new growth and are ready to begin flowering in late July and August.

These giant perennial hibiscus are a great addition to any summer garden, and our B.C. growers will soon have a great selection available in local garden stores.