Tropical Hibiscus and Hardy Hibiscus 

Hibiscus ornamentals include varieties that bloom profusely for months, with eye-catching blooms in a variety of colours up to 30 cm wide. Of the flowering plant genus in the mallow family, there are around 400 different varieties of hibiscus including hardy perennials, herbs, vines, annuals, shrubs, or tropical plants. They are grown for a variety of uses, including decorative blossoms, food, and fiber plants.

Hibiscus Varieties

Originally, hibiscus was only found in the tropics. In recent times, breeders have been developing beautiful “hardy hibiscus” varieties that have been well adapted to northern regions, including Canada. Here are the three primary types:

Hardy hibiscus

Hibiscus moscheutos, often known as swamp rose mallow or simply rose mallow, thrives in zones 4–9. It is a cold-hardy wetland plant found in swamps, marshes, and damp areas near rivers and ponds. Even if temperatures dip below freezing in the winter, hardy hibiscus plants will flourish and bloom in your front or backyard garden. From mid-summer through October, they may bloom in pink, white, or purple blooms in a variety of settings. Their blooms may be as little as four inches long and as large as ten inches broad, and the plant as a whole can grow to be two to ten feet tall.

A huge deep red coloured Hibiscus moscheutos,flower
Courtesy Wikimedia Commons

The blossoms of hardy hibiscus are among the largest of any perennial garden shrub. The “Dinner Plate” hibiscus is a cold-hardy shrub with massive, flat circular flowers that can reach 9″ (22 cm) in diameter. They’re popular as decorative plants because of their fragrant blossoms.

Rose of Sharon

The pink flower of a Hibiscus syriacus also known as Rose of Sharon
Courtesy Wikimedia Commons

Hibiscus syriacus, also considered by some a hardy hibiscus, grows in zones 5-10. This flowering shrub (or small tree) may grow up to eight feet tall and can tolerate below-freezing weather. It has smaller leaves and flowers blooming around two to four inches across. The optimal conditions for this perennial hibiscus are a mix of full sun and moderate shade, as well as acidic, well-draining soil.

Tropical hibiscus

A Hibiscus rosa-sinensis tree, about 8 feet high with a dozen red flowers
Courtesy Wikimedia Commons

Hibiscus rosa-sinensis is a tropical hibiscus for zones 8-11. Their cultivars can withstand high temperatures and are commonly planted outside in subtropical and tropical climates. Outside of their native location, they are frequently cultivated as annuals. If you don’t live in one of these zones, you may grow them in pots and bring them inside during the winter. If the temperature is hot and dry, the tropical hibiscus blooms between summer and fall. In hot weather, this hibiscus may become quite thirsty, demanding frequent watering. This hibiscus can grow up to 15 feet tall and has blooms that range in size from three to ten inches in diameter.

How to Grow Hibiscus

Indoor Light

Hibiscus can also be grown indoors as annuals or perennials and are often grown as houseplants. They are able to thrive in a container; plant in a big container. They have to be kept in a bright spot near a sunny window, but not in direct sunlight.

Outdoor Light

Hibiscus grows best in full light. However, in southern zones, owing to the intensity of sunshine and heat, filtered sunlight may be preferable.

Watering

Water your hibiscus deeply every week during its growing season. It can be thirsty plants when growing. A drought is not their friend. Add mulch and/or compost on top.

Soil

Hibiscus can grow in a wide range of soil conditions, but it prefers soils that contain organic matter and are slightly acidic and loamy. Hibiscus moscheutos and many of their herbaceous, hardy perennial cousins are swamp natives, so they require plenty of moisture. Soil acidity can affect colour: the more acidic, the deeper the pink, while grey or green indicates a base.

Mulch

Hibiscus don’t like to be submerged in soil, and they like moist soil. So, spring and summer, mulch them to keep the soil from getting too dry.

Overwintering

Mulching the base of shrubs in late fall will increase overwinter survival; straw can also be used. Hardy Hibiscus dies back to the ground for winter. It will reappear in late spring or early summer, in part depending on how hard the winter was. Mark its placement so that you don’t accidentally dig it up in the spring.

How to Prune and Trim

Prune an established hibiscus to keep growth in check; winter pruning is highly recommended. You can prune aggressively. Pruning selected branches permits you to shape the plant. Pruning spent flowers will encourage blooming. Remove yellow leaves and damaged or diseased branches. Pinching growing tips leads to a fuller bush. Click here for the full article on pruning hibiscus.

Fertilizing

Hibiscus loves extra nitrogen, so fertilize them moderately during their growing season with an all-purpose, slow release fertilizer. Dilute feeding every two weeks. If desired, acidify the soil to influence flower colour.

Pests

Meal bugs, spider mites, aphids, and whiteflies are common pests of hibiscus plants. If you experience problems with pests, try growing your hibiscus in a container. Or, have a plan to remove pests. Here’s a great article on removing aphids.

Propagating

From Seeds

Hibiscus Seeds and Seed Capsules
Hibiscus Seeds and Capsules from wikimedia commons

It is more difficult to grow hibiscus from seeds than from cuttings or division. Note that Hibiscus rosa-sinensis, for example, often does not produce seeds.

Seeds might take a long time to germinate and require a lot of care.

  • Harvest seeds for germination in the fall.
  • Start seeds indoors 12-14 weeks before planting after the last spring frost.
  • Make a small cut in the seeds with a sharp knife to allow moisture to penetrate the seed.
  • Soak the seeds overnight, then plant them in a light soil mix about 5mm deep (1/4 of an inch).
  • Cover seeds with vermiculite and keep the soil evenly moist. Keep the soil moist by placing it in a warm location and covering it with plastic.
  • Transplant seedlings once they are large enough to handle without pinching, in full sun.
  • Water and fertilize regularly.

Seedlings appear between two and four weeks after planting. They will need gradual hardening off before transplanting.

From Cuttings

Hibiscus cutting which has rooted
Hibiscus Rooted Cutting

Stem cutting is the simplest technique to propagate hibiscus.

  • Spring is the best time for propagation by cuttings.
  • Remove the bottom leaves from a 6-inch (15-cm) healthy softwood stem in the spring.
  • Dip the end of the branch in rooting hormone and plant it in a container with loose, wet potting soil.
  • To improve humidity, place a plastic bag over the pot.
  • Then, put it somewhere warm, at least 60 degrees Fahrenheit (15 degrees Celsius).
  • Maintain a wet potting mix.
  • The growth of fresh leaves and the appearance of roots should take between one and two months.
  • Before transferring it to a sunny place in your yard, transplant the roots cutting to a bigger container and cultivate it for a season.

Transplanting Hibiscus

Mature hibiscus does not tolerate transplanting well. A thorough preparation is essential for effectively transplanting a hibiscus. The best time to transplant a hardy hibiscus is in early fall, after the perennial has completed flowering.

Hibiscus Tea

Hibiscus tea is made from dried petals. To dry petals, the hibiscus flowers need to be free of pesticides and dried in the sun on a drying rack. A quicker method, if you are in a rush, is to drop them into a food dehydrator. Once dried, they can be used for teas, potpourri, dried flower art and wreathes.

Tea is easy to make from dried petals. There are many recipes, here is one for your consideration  Here is one recipe.

Are flowers edible?

Hibiscus flowers are edible, but the seeds are not. The edible parts of the plant are the leaves, flowers, and petals. The flowers have a strong, minty scent that is often used in perfumes and foods. The dried petals are often used in confections and tea.

Yes, Deer Eat Hibiscus

Hibiscus flowers, buds, leaves, and stems are all eaten by deer. They are a favourite of deer since they are well-watered, fertilized, and edible to them.

Hibiscus Health Benefits

  • In clinical trials, drinking hibiscus tea has been shown to lower blood pressure in humans. 
  • Hibiscus is used as a treatment for mental health conditions.
  • Hibiscus is used to improve mood and treat anxiety.
  • Treat hyperactive children.
  • Improve digestion, treat constipation and improve digestion.
  • Protect Skin: The high vitamin C content in hibiscus protects skin from sun damage.
  • Alleviate Headaches.
  • Prevent colds.
  • A natural bug repellent.
  • Hibiscus is used in traditional Chinese medicine to improve memory.

British Ships Named Hibiscus

The British have named ships after plants more than any other nation. Two British Royal Navy vessels were named HMS Hibiscus: HMS Hibiscus (1917), a sloop used until 1923, and HMS Hibiscus (K24), a corvette launched in 1940 and retired in 1946. Several non-naval British ships have also been named “Rose of Sharon.”

Source: Top Canadian Ornamental Plants: Hibiscus Page 45

Final Words: Growing Hibiscus Care Guide

Hibiscus are beautiful tropical flowers that are often grown as annuals or as houseplants. They can be grown in a wide range of climates and are often used to improve mental health and mood, treat anxiety, and improve memory. Hibiscus flowers can also be eaten and are often used in cosmetics and fragrances.  The hibiscus is a great plant for a sunny window. They are easy to grow and require very little maintenance. When you grow hibiscus, you will enjoy the beautiful flowers and impressive perennial growth

Sources:

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