Plant of the Month: San Marcos Hibiscus

May 21, 2023

Description of San Marcos Hibiscus, Gossypium harknessii: This rounded shrub blooms from October to May in mild-winter areas, but where it freezes back, flowering can be expected from June to October. Each 2-inch-wide flower has five yellow petals with a maroon spot at the base. The fruit is a rounded capsule, about ½ inch long. The heart-shaped leaves are entire (meaning they are smooth-margined) to shallowly three-lobed, 1 ½ inches wide and 2 inches long. San Marcos Hibiscus reaches a height of 3 feet and a width of 4 feet at maturity.

Native Distribution: Baja California, Mexico, is the only place where San Marcos Hibiscus occurs naturally. It grows mostly near the sea, in sandy or rocky arroyos and on slopes.

Pic of San Marcos Hibiscus with flowers and leaves
Glossy heart-shaped leaves resemble English Ivy. Photo: Donna DiFrancesco

Culture: San Marcos Hibiscus is cold tender, but even though it freezes to the ground at 28 F, it will grow back from the roots. The frost-damaged stems can be removed in early spring, when all danger of frost is past. Provide a planting site with well-drained soil and full sun. A deep soaking about twice a month during the summer will promote faster growth and more profuse flowering.

Landscape Use: Use San Marcos Hibiscus for a foundation planting; the moderate-sized shrub can help provide a visual link between the building and landscape while deriving some protection from cold temperatures. In mild-winter areas, it could be incorporated into mixed desert plantings. The shrub’s bloom could lend color to patio areas or courtyard gardens. San Marcos Hibiscus’s deep green foliage would create a striking contrast to gray-leaved plants.

Pic of San Marcos Hibiscus showing shape of plant
San Marcos Hibiscus makes a great foundation plant and is both drought and heat tolerant. Native to the shores of the Sea of Cortez, the plant is very salt tolerant. Photo: Donna DiFrancesco

Did you know that up to 70 percent of water use is outdoors? That’s why we love desert plants and feature them each month. You can learn more about San Marcos Hibiscus and other plants on our Arizona Low-Water-Use Plants page. Visit our page on Choosing and Planting Low Water-Use Plants for tips on plant selection and how to plant properly. Also, be sure to read through all of our featured Plant of the Month blogs!

From time to time, Water – Use It Wisely features guest bloggers who write about topics related to water and water conservation. Judy Mielke is a horticulturist, Landscape Architect and the author of one of Water – Use It Wisely’s favorite books. You can find plant descriptions like this and many more in her book Native Plants for Southwestern Landscapes.