Gratiola officinalis, or Hedge Hyssop, is a rhizomatous perennial herb native to Europe. The 4-angled stems will reach about 2 feet (60 cm) in height. Leaves are linear-lanceolate to 1 inch (2.5 cm) long. They are native to marshes and wetlands and are occasionally found along streams. Warning: All plant parts are considered poisonous. They are hardy in USDA zone 6.
Blooming: In the greenhouse, the plants bloom from June to October. The small yellow-white flowers are about 10-18 mm long.
Culture: Gratiola officinalis needs full sun to partial shade with a moist to wet soil mix. In the greenhouse, we use a soil mix consisting of 1 part peat moss to 2 parts loam to 2 parts sand. The plants are grown in shallow trays with at least 1 inch (2.5 cm) of water at all times. We fertilize plants monthly with a balanced fertilizer diluted to 1/2 the strength recommended on the label. Plants are very vigorous growers and need to be re-potted on a yearly basis. During the winter months, the plants are allowed to go dormant and kept in cold rooms at 48°F (9°C). Plants are never allowed to dry out thoroughly during this period.
Propagation: Gratiola officinalis is propagated from cuttings, division and from seed.
Gratiola officinalis was featured as Plant of the Week July 15-21, 2005.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.