Swamp Hibiscus Plant Profile

A Showy Plant That Thrives in Humid Conditions

A Swamp Hibiscus Flower close up in a marsh area

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There are over 200 Hibiscus species, and the Swamp Hibiscus (Hibiscus coccineus) is one of the more unusual varieties. It features a unique and beautiful flower and is vigorous and hardy when grown in the right conditions.

With strong woody stems, it can grow up to six feet tall. The deep red and showy five-petalled flowers add a wonderful splash of color to moist garden sites throughout the summer. It's completely herbaceous and will die back in the winter before producing fresh growth in the spring.

When it isn't in flower, with its deep-green, thin and pointed leaves, it can sometimes be mistaken for the Hemp Plant (Cannabis sativa).

As you might guess from the name, this plant thrives in moist conditions. It's a great choice for planting around a pond or next to a stream. Because of its height, it also works well at the back of a perennial border or along a courtyard wall.

Botanical Name Hibiscus coccineus
Common Name Swamp Hibiscus, Scarlet Rosemallow, Texas Star Hibiscus
Plant Type Herbaceous perennial
Mature Size Up to 6 feet
Sun Exposure Full sun/Partial shade
Soil Type Tolerates a variety
Soil pH Tolerates a variety
Bloom Time July to September
Flower Color Bright red
Hardiness Zones 6 to 9
Native Area Southeastern United States

How to Grow Swamp Hibiscus

Swamp Hibiscus is a vigorous grower in the right conditions. These plants thrive in sunny, humid conditions in a moisture-retaining soil.

They can grow to be over six foot tall and may need staking, depending on their height and position.

Light

Swamp Hibiscus does best in full sun or partial shade. It can survive in shadier positions, but this usually means the stems will grow overly long and thin, and it will be more prone to collapsing. The blooms that appear aren't likely to be as impressive either.

Soil

This plant usually does well in sandy, loamy or clay soils. Unlike a lot of other plant species, it can cope with wet soils with medium drainage.

If you live in a drier region, mulching can help the soil to retain much-needed moisture.

Water

The key to success with the Swamp Hibiscus is to ensure that it's kept moist during the growing season. From spring right through to fall, it will need regular watering.

Although it will only need very limited watering in the winter, it's still best not to let the soil dry out completely.

Temperature and Humidity

This plant prefers hot and humid summers. If you live in a more temperate region, making sure it has a good layer of mulch during the winter will help promote new growth the following season.

Even with mulch, this plant isn't suited to areas that are prone to harsh freezing winter conditions.

Swamp Hibiscus can be susceptible to windburn. For this reason, and because of its height, positioning it in a sheltered position is recommended.

Fertilizer

Monthly applications of a slow-release, balanced and diluted fertilizer during the growing season can be beneficial.

Propagating Swamp Hibiscus

To propagate Swamp Hibiscus, take a six-inch cutting from a healthy plant in the spring, dip it in rooting hormone, and then press it into a peat moss filled container.

Keep it moist and out of direct sunlight. When new leaves start to appear, the cutting can be transplanted to its permanent position.

Pruning

To keep the height of your Swamp Hibiscus in check, cutting the stems back towards the end of the winter can encourage healthy new growth.

These plants are fast growers and will reach a decent height again the following season.

Growing From Seeds

Swamp Hibiscus grows well from seeds. If you're collecting seeds from your existing plants, wait until the seed pods at the base of the flowers turn from green to brown. The seeds within can be stored until the early spring.

At this point, they can be sown into moist potting soil. The seedlings will do well in a sunny position, and the soil shouldn't be allowed to dry out.

Transplant the seedlings to their permanent position after the last spring frosts are passed.

Common Pests/Diseases

Although this is a hardy plant, pests such as aphids can sometimes be an issue. Sometimes it can be enough to spray cold water on the leaves to remove the insects. Insecticidal soaps can also be effective.

Plants with woody stems, like the Swamp Hibiscus, can sometimes be prone to a fungal disease known as rust. Orange spots, similar to the color of rust, can begin to appear on the leaves.

These sections should be removed by pruning. If the problem isn't cleared up by winter, cutting the stems right back to the ground will eliminate the issue. New and fungal-free growth should appear the following season.