Don’t let those huge blooms fool you! It is easy to grow hibiscus with dinner plate-sized flowers if you follow a few simple tips. Yours will be the envy of the neighborhood every summer if you treat them right!
The tropical flair that perennial hibiscus exudes may fool you into thinking they wouldn’t be hardy in your area, but chances are good you can grow this amazing perennial where you live. Its hardiness ranges from zone 4 (-20°F to -30°F), which extends as far north as Minnesota, to zone 9 (20°F -30°F), which includes hot, humid climates like Florida and North Texas. It can be grown outdoors in your garden without bringing it in for winter in those zones.
They aren’t to be confused with tropical hibiscus which are grown as houseplants in all but the warmest climates, or with the shrub form Hibiscus syriacus, commonly called rose of Sharon.
Perennial hibiscus needs three main things to thrive: sun, water and space. Each should be provided in abundance. Let’s take a closer look.
Perennial hibiscus needs lots and lots of sunshine to grow well, develop its proper coloring, and bloom well. The best place to plant your new hibiscus is where the sun shines all day long. Full sun (6+ hours) is especially important for those grown as much for their dark purple foliage as their dinner plate-sized blooms. The purple coloring develops as a response to UV light from the sun, so plants grown in shade will have greener leaves.
Sun provides energy for hibiscus to form its flower buds. Even if you live in the South0, you should grow hibiscus in full sun to maximize its flower power. If your only choice is to grow it in part sun, make sure it receives at least a few hours of warm afternoon sun.
Perennial hibiscus are very thirsty plants. In their native habitat, they can grow in shallow water and along streambanks. They also thrive in humidity. If you live in an arid climate, this perennial is not the best choice for your garden.
Be sure to plant your perennial hibiscus where the automatic sprinkling system will hit it on a regular basis. If you hand-water your garden, plant it near your hose to make it easy to give it a drink frequently. Try not to let the soil dry out much, especially if you have clay which can become very hard when it’s parched. Amending the soil with compost at planting time and mulching around the base will help to retain moisture.
You know your perennial hibiscus is not getting enough water if:
- The whole plant is drooping
- The flower buds are turning yellow and falling off before they open
- The leaves start to turn fall colors well before that season has arrived
Some people are surprised when perennial hibiscus dies all the way back down to the ground in the fall. They assume a plant of this size would be a woody shrub, but it actually is an herbaceous perennial. As such, the plant drops its leaves late in the fall and comes back from the roots the following spring.
Perennial hibiscus range in size from about 3 to 6 feet tall and usually grow wider than they are tall. They also mature very quickly. If you are starting with a small plant, don’t be fooled into thinking you can plant it someplace temporarily and then move it in a few years. Its large root system will make it difficult to transplant after just a year or two.
A better idea is to plant your new hibiscus somewhere it will have plenty of room to mature over the next few years. Fill in around it with colorful annuals for the time being as it grows. Each year, you will need fewer annuals to fill the surrounding space. By the end of year three, your perennial hibiscus will be nearly full grown.
It is important to cut down all of the old, woody stalks of perennial hibiscus every year in the spring to make way for the new growth. You can see how the new growth emerges from the roots in this video. No new foliage will grow from last year’s stems—this perennial re-sprouts all new growth every year, just like any other herbaceous perennial.
If you look closely at this picture, you will notice that the center of a perennial hibiscus stem is hollow.
Rain and snow can get into those hollow cut stems and cause rot or freeze/thaw in the crown of the plant when the plant is not actively growing. It is for this reason that we recommend cutting the plant down in spring rather than in the fall.
Use a hand saw or a sharp pair of loppers or pruners to cut down the stalks to a height of about 6 to 8 inches. This will expose the crown of the plant to the sun and stimulate new growth.
No additional pruning should be needed or is recommended throughout the season. If your perennial hibiscus grows taller than you’d like it to, do not trim down the stems because doing so will sacrifice the flowers. Better to wait until next spring to transplant it someplace where its full size will be appreciated.
Botanically speaking, perennial hibiscus is in the rose family, and Japanese beetles enjoy attending the family reunion each year just like they do with roses. If this pest is an issue in your area, the long-term solution is to treat for them when they are in the grub stage in your lawn. Milky spore is considered one of the best treatments, but it takes a couple of years to work well. In the meantime, knocking off the beetles into a bucket of soapy water is effective.
Watch also for hibiscus sawfly larvae which looks like a small green worm in its juvenile stage. Like Japanese beetles, they chew holes in the leaves, sometimes quite extensively. Systemic insecticides are effective on sawfly larvae.
A NOTE ABOUT YOUR NEW HIBISCUS FROM GARDEN CROSSINGS
Here are a couple of things you’ll want to know about the new hibiscus we ship to you:
- Like we mentioned above, purple-leaf hibiscus need exposure to the sun’s UV rays to develop their purple coloring. The plant you will receive was grown in our greenhouses which do not let UV rays in, so you can expect its foliage to be green when you receive your plant. Once you set it outside in the sun, the leaves will quickly regain their purple color.
- Any perennial you buy from a garden center, including hibiscus, may bloom off cycle the first year. Factors like when it was planted in the pot and how it was trimmed to fit in a shipping box can all affect blooming. Your new hibiscus might bloom this year, but it is more likely that it will flower the following year at its natural time in mid to late summer.