Rose Mallow
Garden Clippings for Aug 6, 2022
Are Hibiscus flowers too big for their own good?
Perennial Hibiscus, more commonly known as Rose Mallow, certainly do take centre stage in the flower garden. Blooms open so wide that they’ll take up all the space on a dinner plate.
For Rose Mallow, it is not only their size that matters. Their bright paper-like petals form blooms that command attention like no other perennial. Colours range from pure white to bold pink to burgundy red.
Rose Mallow behaves oddly in the garden. Its height ranges from 3 to 5 feet, making it unsuitable for container gardening.
A single clump of Rose Mallow can produce 8 to 10 stems a year or two after planting. Its bold textured leaves are true green, with a shape and size of a Maple leaf.
Flowers appear in late July, when other summer flowering perennials are in their full glory. Flowers are short lived but are quickly replaced with new flowers offering a riot of colour through August and September.
Rose Mallow is a tropical looking plant often causing northern gardeners to doubt their suitability for cold climates. But surprise, surprise, Rose Mallow is hardy to Zone 4 or 5, giving them ability to easily survive anywhere in Southwestern Ontario and eastward towards Toronto and Montreal.
Give Rose Mallow a spot that receives at least 6 hours of sun per day. Planting in shade will cause the plant to stretch and produce less vibrant blooms.
Rose Mallow does not have fussy soil or nutrient requirements. At planting time, give them a loamy soil blended with triple mix or manure and they will be happy. Rose Mallow’s only sticking point is their need for water. During periods of prolonged summer draught, they will indicate their displeasure by wilting in summer heat. Adding a layer of wood mulch at the base of the plant will help retain soil moisture.
Another odd growing habit for Rose Mallow is their reluctance to begin growing until late spring. Long after the crocuses sprout, Forsythias bloom, and grass turns green, will the Rose Mallow finally send new shoots from the ground. I have seen Rose Mallow wait till June before soil is warm enough to trigger stem growth.
Don’t confuse perennial Hibiscus or Rose Mallow with the popular tropical Hibiscus often grown as an annual. In many ways the two cousins are similar, but the tropical Hibiscus is not cold hardy and will need to be brought indoors before frost. Tropical Hibiscus has smaller leaves and smaller flowers and grows beautifully in a container outdoors. Bring them inside before winter to enjoy as a houseplant.
Perennial Hibiscus is also often confused with Rose of Sharon, another cousin. Rose of Sharon is a hardy shrub with masses of blooms appearing late in summer and into fall. The shrub can grow to 8 or 10 feet, sporting 3 to 4 inch diameter flowers. If left unattended, Rose of Sharon shrubs will grow to an inverted cone shape. Interestingly, Rose of Sharon, like Rose Mallow, will often be the latest shrub to sprout in spring.
