Halberdleaf rosemallow (Hibiscus militaris or H. laevis) is a wildflower that needs plenty of sun and moisture. In its home states, including Illinois and Minnesota, it grows on riverbanks, next to ponds and in low wet areas, such as marshes. West Coast gardeners who have ponds, rain gardens or boggy spots in their yards may want to try this relative of the hollyhock. Butterflies are attracted to Its rosy-white trumpet blossoms, which have crimson-to-purple centers.
Botanically, the halberdleaf rosemallow is more commonly known by its newer Latin name Hibiscus laevis. Sometimes it is also called soldier hibiscus. The "militaris," "soldier" and "halberd" parts of its various names allude to the similarity between the shape of its leaves and the lance end of a medieval pole-ax called a halberd. The leaves have pointed tips and a broad, deeply lobed base with a silhouette similar to a double-headed ax. Unlike many hibiscus family members, the Halberdleaf rosemallow has smooth leaves and stems. Similar to its hairy cousin, the hollyhock, it grows upright, reaching a height of 3 to 6 feet. Each five-petal blossom grows out of a leaf axil, the point at which a leaf joins the stem. Blooms emerge from the bottom to the tip of the stem. The Lady Bird Johnson Wildflower Center notes that the flowers may bloom from May to November, depending on the region.
Temperature and Location
Halberdleaf rosemallow grows well in U.S. Department of Agriculture Hardiness Zones 4 to 9. Halberdleaf rosemallow is an adaptable perennial, but its seeds spread slowly, according to the U.S. Department of Agriculture. It is native to 28 states in the Midwest, the South and the East Coast. Sunny locations are best, but Halberdleaf will also grow in part shade. In either situation, it needs lots of water.
Soil and Water
The USDA notes that Halberdleaf rosemallow doesn't tolerate drought. So watering likely would be necessary at times in most California gardens. Soils can range from clay to sand and should have a fine to medium texture. While most flowers prefer soil chemistry that is close to an even balance of acidity and alkalinity, hibiscus species prefer acidity. Halberdleaf rosemallow can live in soils with a pH range of 5.5 to 7.2.
Although halberdleaf rosemallow sometimes is sold at West Coast nurseries, purchasing seeds online is a more likely way to obtain the plant. Place the seeds in a finely textured potting mix, planting them at twice the depth of their size. Before planting, nick the flat bottom of each seed to allow easier absorption of water and to speed growth. Germination may take up to 20 days. Once the seedlings are about 3 inches tall, they can be transplanted to planters or the ground outdoors. As to rooting hibiscus vegetatively, the University of Minnesota Extension recommends taking a 3- to 5-inch cutting from a strong shoot, such as a flower tip. Dip the cutting in rooting hormone, then plant it in potting soil. Also, you can collect seeds from your flowers' dried pods when they burst late in summer.
- Missouri Botanical Garden: Hibiscus Laevis
- Lady Bird Johnson Wildflower Center: Hibiscus Laevis All.
- U.S. Department of Agriculture: USDA Plant Hardiness Zone Map
- U.S. Department of Agriculture: Plants Database: Characteristics: Hibiscus laevis All. -- Halberdleaf Rosemallow
- J.E. Luddick, Hibiscus Hybridizer: Planting Seeds
- University of Minnesota Extension: Hibiscus
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