Scutellaria is a large genus of herbaceous perennial plants in the Lamiaceae (mint) family. Other related herbs in the mint family include lavender, rosemary, and basil. The genus was named after the latin word “scutella” which means a small dish or cup in reference to the shape of the calyx after flowers fall.The common name of “skullcap” refers to military helmets worn in the Middle Ages.
There are hundreds of skullcap herbs around the world which have adapted to different growing conditions. In North America, the most widely found is the native Scutellaria lateriflora species with the fitting common name, the American skullcap.
There are also regional varieties found around the world including Scutellaria suffrutescens (pink skullcap) and Scutellaria californica (California skullcap). One of the most widely studied skullcap varieties is Scutellaria baicalensis (Chinese skullcap) which has been used in traditional herbal medicines for thousands of years. Many skullcap products are found on the market today as herbal treatments.
Skullcaps are relatively easy to grow and face few pests and diseases. They bloom in showy splashes of pink, purple, white, and blue flowers. Different skullcap herb types are suitable to different growing conditions, but in general, their hardiness and beauty make them an excellent and colorful addition to many landscapes.
Quick Care Guide
|Common Name||Blue skullcap, mad dog skullcap, side-flowering skullcap, cherry skullcap, Mexican skullcap, pink Texas skullcap, pink skullcap, California skullcap, Chinese skullcap.|
|Scientific Name||Scutellaria spp.|
|Height & Spread||2-3 feet tall, 1.5-2.5 feet spread|
|Light||Full sun to partial shade|
|Soil||Most species prefer well-draining soil. Different species have different preferences for soil acidity.|
|Water||Medium to wet depending on species|
|Pests & Diseases||Aphids, whiteflies, powdery mildew|
All About The Skullcap Plant
The skullcap plant, Scutellaria spp., is an herbaceous perennial plant in the mint family. As with many mints, this plant also has square stalks and spreads by rhizomes and runners. They may have compact, cushion, or mound-forming growth habits.
The aerial parts of the plant will die back in the winter and come back as new crops by forming bright green basal rosette clusters in the spring. Many stems will emerge from the rosette as the season progresses. Use the skullcap herb in your landscape as a wildflower border, by a pond, or as part of a rock garden. The flowers have an added benefit of attracting pollinators.
There are many different species in the Scutellaria genus, but they all share the tell-tale characteristics of having skullcap-shaped calyx at the base of their flowers. The tubular, two-lipped, and indeterminate flowers are arranged on upper leaf axils similar to the look of snapdragons. Leaf axils will typically have up to 14 flowers.
Leaves are ovate and arranged in an opposite configuration along the stems. Leaf colors range from lime green to dark green and some have leaves with toothed margins. Many common names of skullcaps are named after colors such as the pink skullcap, cherry skullcap, and blue skullcap. Skullcap may be spelled scullcap as another variation.
Some 35 species of skullcaps have been studied for their pharmacological potential with Scutellaria baicalensis being the most widely studied due to its high concentrations of flavonoids. While not regulated as a medicine in the U.S., consumers can find skullcap tea and extracts sold on the market as herbal treatment for anxiety, sleep disorders, and more.
Types of Skullcap
The Scutellaria genus includes approximately 350 different plant species found all over the world in temperate areas. There are many species native to North America. These herbs are grown for both their ornamental and medicinal value.
The Scutellaria lateriflora species (American skullcap) is an herb that is native across North America and can be found as far north as Quebec and Newfoundland and as far south as Florida. This skullcap is adapted to wet environments such as marshy meadows, floodplains, ponds, streams, etc. They have three variations of color: pink, white, and blue flowers.
They bloom from July to early October and are very suited to wetland areas. The name “lateriflora” means “flowering on the side” because the flowers bloom along one sided racemes. This species is also commonly known as blue skullcap, mad dog skullcap, mad dog weed, and side-flowering skullcap. Researchers are actively studying the effects of the blue skullcap herb on anxiety and sleep disorders.
Scutellaria baicalensis (Chinese skullcap) is indigenous to East Asia and parts of Russia. For thousands of years, the Chinese have been using the roots of this plant in traditional and natural medicines to treat various ailments including diarrhea, dysentery, hypertension, etc. It’s also commonly known as the Baikal skullcap or Huang Qin. Similar to Scutellaria lateriflora, this skullcap herb also produces blue and purple flowers.
Scutellaria suffrutescens (pink skullcap) is known for its showy bloom of pink flowers. Despite one of its common names being the pink Texas skullcap, this herb is not native to Texas, but took off after its introduction due to its tolerance to droughts. It can be best grown in rocky or sandy soil with good drainage and in full sun with some afternoon shade. This plant has a woody base that does not die down annually and its leaves are semi-evergreen in frost-free regions.
Scutellaria californica (California skullcap) is an herb native to the low elevation mountains of Northern California. This plant produces small yellow and white flowers that bloom in June and July and is said to smell like apples. It prefers to grow in well-draining soil and in an area with partial shade.
Skullcap Plant Care
Skullcap herbs are easy to care for once established. However, different varieties of this plant have different requirements. Some, like the Scutellaria lateriflora, are common in wetlands while others, like the Scutellaria suffrutescens, are very drought tolerant.
Sun and Temperature
Different Scutellaria species have different hardiness, sun, and temperature requirements. S.lateriflora has the widest range and can be grown in USDA hardiness zone 2b to 7b. Other herb species have much more limited range and prefer zones 6b to 8a. In general, Scutellaria spp. grow best in 6 or more hours of direct sunlight per day with some partial afternoon shade. Sun is a major factor to the quality and quantity of flowers.
Water and Humidity
Water and humidity requirements vary greatly depending on the variety. When thinking about introducing a skullcap to your garden, carefully consider your current conditions and choose a variety most suitable for your needs. Many are drought-tolerant after being established.
Most Scutellaria spp. prefer medium to well-draining soil that’s high in organic matter and has sandy or shallow rocky textures. Soil pH preferences also vary depending on type. When grown as a medical herb, Scutellaria plants are specifically put under environmental stress such as poor soil quality to promote the production of flavonoids.
Fertilizing Your Skullcap Plant
Skullcap flowers and foliage.
Scutellaria spp. are hardy herbs that do not need fertilization once established. If you are trying to promote more flowers, use a slow-release fertilizer and follow the manufacturer’s instructions. Choose a fertilizer low in nitrogen to promote flowering instead of leaf growth.
Pruning Your Skullcap Plant
Pruning aerial parts is beneficial for this perennial herb. Early spring is a good time to prune old woody limbs and to promote more full growth in the middle of the plant which tends to thin out with time.
Skullcap Plant Propagation
Many Scutellaria spp. can germinate from seed or be propagated through taking root cuttings. They can be planted anytime during the year and have a tendency to self seed. Each flower stalk can produce many small black seeds. Seeds need a period of cold stratification and may take up to 30 days to germinate. Nurseries that specialize in native plants will often sell ready-to-transplant seedlings.
Scutellaria spp. are hardy herbs once established in a garden. They have very few pest and disease issues and are even deer resistant.
While Scutellaria herb varieties can flower if grown in partial shade, the best condition to promote abundant flowers is to plant them in full sun. Because different types of skullcap plants have different growing needs, it is important to make sure you select the right type for your needs in the garden.
Do not use a variety that is well adapted for wetlands in an arid rock garden and vice versa. For example, the mad dog skullcap or blue skullcap (Scutellaria lateriflora) prefers moist soil and swampy conditions, whereas the pink skullcap (Scutellaria suffrutescens) is native to Mexico and suitable for arid environments.
Skullcap plants do not face serious pest issues. In fact, many gardeners specifically choose to use skullcap herbs in their landscaping because they are not consumed by deer, rabbits, or geese due to the bitter taste and mild toxicity of the leaves.
Some varieties of skullcap herbs may be susceptible to aphids. These are soft-bodied insects that use their piercing and sucking mouthparts to feed on different plants. Because many aphids are plant generalists, they could feed on skullcaps. Aphids are commonly found on the bottom side of leaves.
Prune off heavily infected leaves or branches and spray the plant with a strong stream of water to knock off any remaining insects. Because the skullcap herb is an important food source for pollinators, use chemical sprays as a last resort. Neem oil and insecticidal soap can be used every 7-10 days before sunrise and at dusk to minimize their impact on pollinating insects.
Whiteflies might be another pest that impacts skullcap plants, especially if the plant is grown inside a greenhouse. Similar to the treatment of aphids, a blast of water, neem oil and other horticultural oils, and insecticidal soaps can be applied to treat a whiteflies infestation.
If there is an issue with whiteflies, it’s likely to be on many different plants and not just on the skullcaps so it’s important to control the overall pest population in the garden or greenhouse.
Skullcap plants are not very susceptible to diseases and are very hardy. There have been some reported cases of powdery mildew on skullcaps, although this is an occasional issue. Powdery mildew is a fungal disease that covers plants in a white coating of powdery spores. As the disease progresses, it hinders the plant from photosynthesizing and saps the plant of nutrition.
There are various treatments for powdery mildew including spraying the plant with a sulfur spray, a milk spray, diluted baking soda, and neem oil. You can also prevent development of powdery mildew by making sure there is good air circulation around the plant and keeping the leaves dry. Similar to whiteflies and aphids, powdery mildew is also more likely to occur on skullcap plants in greenhouse settings.
Frequently Asked Questions
Q: Is skullcap a perennial?
A: Skullcap herb species are perennials that spread by rhizomes below the soil and runners above the soil.
Q: Is skullcap plant invasive?
A: The skullcap plant is a fast grower, but not invasive. There are different skullcap herb varieties that are native to North America including the American skullcap (Scutellaria lateriflora), the pink skullcap (Scutellaria suffrutescens), and many others. These plants can produce an abundance of seeds and can self seed to cover a large area of ground in just a few years.
Q: Where should I plant skullcap?
A: Skullcap herbs are an excellent plant for ground cover in sunny areas, rock gardens, and by the edge of ponds.
Q: When should I pick my skullcap?
A: Up to ⅔ of the plant can be harvested in August or when the flowers are in bloom.
Q: How long does skullcap take to grow?
A: Skullcap plants grow very quickly and can reach a full mound shape in just one growing season. Over several years, it can quickly spread and cover large ground to provide showy visual interest in blue, white, pink, and purple flowers.
Q: Does skullcap grow back?
A: Yes, skullcap is a perennial plant and will grow back year after year.
Q: Can I grow skullcap indoors?
A: Skullcap seeds and seedlings are started indoors but then transplanted outside once the danger of frost has passed.
Q: What is the plant skullcap used for?
A: Skullcap herb and specifically the Scutellaria baicalensis (Chinese skullcap) have been used as traditional Chinese medicine dating back to thousands of years. The roots of the plant are used to treat various diseases. There is ongoing scientific research and animal studies on its potential medicinal crop opportunities to treat anxiety, inflammation, etc.