Perennial Hibiscus
This is a rather large family of plants – about 220 species all told of annual and perennial herbs, shrubs, subshrubs and trees.
While you won’t grow too many Hibiscus trees in zone 4, you will likely grow all the other forms. Hibiscus are a member of the malvaceae or Mallow family which lends them a common flower habit with some of our less popular roadside weeds (white mallow) and our more popular garden plants (Lavatera).
Let’s look at a few of the plants you’ll likely find in local gardens.
Hibiscus moscheutos
Hibiscus moscheutos is the plant that garden centers sell as perennial hibiscus. Native to the Carolina forests, most perennial Hibiscus are rated a USDA zone 4 for winter hardiness and down to a warm zone 9 for summer heat tolerance.
They are typically July-August bloomers although a few bloom later than this. If grown in good rich soil, this plant will quickly turn into a four to six foot tall bush every spring (dying to the ground over winter). The flowers will also be amazingly large at six inches across.
I have grown this plant in sand and clay and have abused it terribly, it survives almost every kind of soil although it doesn’t bloom well when drought strikes.
The only problem I ever had was winter-hardiness on some of the dwarf varieties but that might have been my gardening rather than the plant. Given that I like the taller varieties better anyway, it was no loss.
They are usually pruned to the ground in the fall and regrow (starting as one of the last perennials to emerge) each spring.
The most commonly available form of perennial Hibiscus is ‘Southern Belle’ because it is carried by most seed catalogues.
How To Grow Perennial Hibiscus
This wonderful plant, if grown in a moist, rich soil in full sun or part shade can easily hit 4 to 6 feet tall in a season and be covered by a delightful display of huge six inch blooms in late summer.
New Varieties
The breeders have done their magic giving us plants such as ‘Cotton Candy’ pink and white, ‘Satan’ blood red, ‘Radiation’ deep pink, and ‘Crimson Wonder’ with you guessed it – crimson flowers.
’Kopper King’has coppery-red foliage with massive white flowers containing a red eye; this is an excellent show-stopping fall bloomer. I’ve also grown ’Lord Baltimore’ which is a rather large bushy perennial Hibiscus plant with massive bright red flowers and this has received more than its share of garden envy while in bloom.
’Fantasia’ is a compact form, only growing to three feet tall but it does have massive rose-pink flowers.
Transplanting
If you purchase perennial Hibiscus moscheutos, be extremely careful with transplanting. It resents having its roots moved and can turn from a healthy hulk into a basket case with careless moving or even weeding that disturbs its roots.
Mulch around it to control weeds.
Annual Hibiscus
I’ve grown the annual Hibiscus trionum for too many years to remember. This pale yellow blooming form pops up here and there around the garden, self sowing from year to year to give me a late August show of blooms. I’ve never really tried to weed it out as it doesn’t overpower its neighbours. It tends to pick a hole and I leave it alone. I got the seed from England about fifteen years ago and have had it ever since.
You can overwinter this plant quite successfully indoors as a houseplant and it roots quite quickly from tender shoot cuttings.
Seeding is easy and one plant will produce enough babies for the neighbourhood. I rather like its pale yellow blooms and if you can find a plant or seeds, I’d recommend it.
There are other specialized Hibiscus plants around but none of them are truly hardy here and are the province of crazed, specialist gardeners who collect and overwinter them indoors.
Luckily there are enough colours and forms of the above plants to keep any perennial Hibiscus lover busy for a few years collecting them all. Look for me in the garden centres next spring in the Hibiscus section. I’m not crazed, but I can be tempted.
Do you have a question about Perennial Hibiscus?