Downy skullcap: A tough and attractive native plant

Downy skullcap, or hoary skullcap, isn't widely grown but ought to be since it's tough as nails and has lovely flowers.

Courtesy of Gene Bush
What gardener wouldn't want a native plant that looks this attractive, yet is easy to grow, even in dry soil? Those are the virtues of downy skullcap or hoary skullcap, Scutellaria incana.

Even in gardens that rely heavily upon native plants, I seldom see Scutellaria species. My favorite, Scutellaria incana, is an Indiana native and can stand up to the best of European or Asian perennials for shade gardens. None is finicky, and all are easily grown in open gardens.

In fact, they're tough as nails.

Great performance in dry conditions

In its native habitats, downy skullcap (sometimes called hoary skullcap) is usually found growing in dry soil at edge of the woods, or along roadsides. I have seen it blooming well within the interior of woodlands.

During July and August, when weather becomes hot and dry with high humidity, many plants to suffer. Not our downy skullcap. It was made for those conditions and keeps right on performing.

Of course, it also responds to a bit of loving care with a touch of decent soil and a modicum of moisture.

The downy skullcap reaches between 2-1/2 and three feet in height. The overall shape is a very stiffly upright open vase. I have not seen the stems fall over under the weight of the blooms when hit by wind and rain, though.

The square stems will become quite woody by season's end. I cut mine back after they have been hit by a hard frost so the stubble will be gone when the new growth begins the following spring.

Individual leaves are 4-1/2 to five inches in length by about two inches in width. The outside edge of the leaf is lined with rounded teeth. Leaves are a deep matte green.

The numerous blooms are held in racemes at both the top of the stems and in the upper axils. Flowers are of good size, lavender-blue, with each flower having two upper petals fused together to form a hood or cap, thus the common name.

Seedpods are shaped like two little saucers stacked one upon the other, with a lip around the edges. As they mature the pods turn tan with violet/purple lips.

Firsthand experience

My downy skullcap grows along a path at the top of my hillside garden in bright open shade under dogwoods. The soil there is decent, well drained, and near a limestone cliff edge. I have been growing this species of skullcap for at least eight years. During that time I have not seen insect damage, nor any sign of disease.

They bloomed the first year they were transplanted into the garden, and have bloomed reliably each year since, always putting on a good show no matter the weather.

Even though the plants set seed well each year, I have not found them to be weedy. This species is also hardy as an old rock, reaching north into Zone 5 and probably Zone 4.

For companion plants, you may want to consider any summer-blooming anemone, hardy begonias (Begonia grandis) with leaves that are red on the underside, and red lobelia, or cardinal flower, if where you are growing your skullcap is not too dry.


Gene Bush, a nationally known garden writer, photographer, lecturer, and nursery owner, gardens on a shaded hillside in southern Indiana. His website is He also writes the Garden Clippin's Newsletter. To read more by Gene here at Diggin' It, click here.

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