Dame’s rocket (Hesperis matronalis) was introduced to North America from Europe as an ornamental flower. It spread far through the region and is now considered an invasive species for woodlands and prairies in many states. Unlike most plants, the flowers and seed pods of dame’s rocket grow at the same time.
I. Appearance and CharacteristicsÂ
Hesperis matronalis is an herbaceous flowering plant species in the family Brassicaceae. It has numerous common names, including dame’s rocket, damask-violet, dame’s-violet, dames-wort, dame’s gilliflower, night-scented gilliflower, queen’s gilliflower, rogue’s gilliflower, summer lilac, sweet rocket, mother-of-the-evening, Good & Plenties, and winter gilliflower.
These plants are biennials or short-lived perennials, native to Eurasia and cultivated in many other areas of the world for their attractive, spring-blooming flowers. In some of those areas, it has escaped from cultivation and become a weed species. The genus name Hesperis was probably given because the scent of the flowers becomes more conspicuous towards evening (Hespera is the Greek word for evening).
Hesperis matronalis grows 100 cm or taller, with multiple upright, hairy stems. Typically, the first year of growth produces a mound of foliage, and flowering occurs the second year; the plants are normally biennials, but a number of races can be short-lived perennials. The plants have showy blooms in early to mid spring. The leaves are alternately arranged on upright stems and lanceolate-shaped; they typically have very short petioles (or lack them) and have toothed margins, but sometimes are entire and are widest at the base. The foliage has short hairs on the top and bottom surfaces that give the leaves a somewhat rough feel. The larger leaves are around 12 cm long and over 4 cm wide. In early spring, a thick mound of low-growing foliage is produced; during flowering the lower parts of the stems are generally unbranched and denuded of foliage and the top of the blooming plant might have a few branches that end in inflorescences.
The plentiful, fragrant flowers are produced in large, showy, terminal racemes that can be 30+ cm tall and elongate as the flowers of the inflorescence bloom. When stems have both flowers and fruits, the weight sometimes causes the stems to bend. Each flower is large (2 cm across), with four petals. Flower coloration varies, with different shades of lavender and purple most common, but white, pink, and even some flowers with mixed colors exist in cultivated forms. A few different double-flowered varieties also exist. The four petals are clawed and hairless. The flowers have six stamens in two groups, the four closest to the ovary are longer than the two oppositely positioned. Stigmas are two-lobed. The four sepals are erect and form a mock tube around the claws of the petals and are also colored similarly to the petals.
Some plants may bloom until August, but warm weather greatly shortens the duration of each flower blooming. Seeds are produced in thin fruits 5–14 cm long pods, containing two rows of seeds separated by a dimple. The fruit are terete and open by way of glabrous valves, constricted between the seeds like a pea pod. Seeds are oblong, 3–4 mm long and 1–1.5 mm wide.
In North America, Hesperis matronalis is often confused with native Phlox species that have similar large showy flower clusters. They can be distinguished from each other by foliage and flower differences: dame’s rocket has alternately arranged leaves and four petals per flower, while phloxes have opposite leaves and five petals.
II. How to Grow and Care
Light & Temperature
Full sun is perfect for these plants if you’re in cooler climates, but those in warmer ones may want to provide partial afternoon shade to protect their plant. It grows well in zones 3-9. Much of North America falls into the dame’s rocket growing range!
Aim for a minimum of six hours of sun whenever possible. It it’s not scorchingly hot, longer is preferred.
This species is not frost hardy. Sow once the danger of frost has completely passed and it will emerge in early spring. It prefers a temperature range of 70-85 degrees for best growth.
Water & Humidity
Consistent watering of about an inch per week during non-rainy weather is the best way to maintain your dame’s rocket. Be sure that excess moisture freely drains away, as soggy soil can lead to root rot.
While it’s tolerant of extra humidity indoors, most outdoor plants don’t need it as long as they’re consistently watered. Adding mulch around your plants also will help keep the humidity up. Indoors, provide a pebble tray with water underneath your pots to combat the typical dry conditions found in a central air environment.
Soil
As long as the soil is well-draining, Hesperis matronalis will grow in it! It’s tolerant of all types of soil, but performs the best in a blend of sandy soil and loamy soil, like those of the woodland edges it tends to.
Tolerant of multiple pH ranges as well, it can grow in pH levels ranging from 5-8. Aim for a neutral range and it should be fine.
Fertilizing
You really don’t need to fertilize dame’s rocket. This plant needs only the slightest bit of soil nutrition. Applying about an inch of compost around your plants once a year should be plenty of fertilizer for their needs.
Planting Instructions
Pruning
Most of your pruning will center around keeping dame’s violet trimmed down to a reasonable height and deadheading flowers or seed pods. In the late summer, trimming it back to a shorter height is recommended to prevent self-seeding.
Propagation
Propagation of dame’s rocket is easiest from self set seed. Most of the seed this species produces has a germination rate of about 70%, meaning that 70% of the dame’s rocket seeds sown will sprout.
Lightly sprinkle your seeds across the surface of the soil, adding just enough to cover them by about twice their depth. Make sure you keep the potting mix damp, but not soggy. Place your pots somewhere sunny, as they require a 70-85 degree soil temperature range to germinate.
While it is possible to grow dame’s rocket from stem cuttings, they don’t root particularly well. Use of a rooting hormone may help them to produce better roots. Rooting hormone is widely available in garden shops across the United States.
Pests and Diseases
- Growing Problems
Dame’s rocket has very few growing problems. About the only one to be concerned about — aside from its classification as an invasive species — is sunburn during the height of summer. Providing some shade during the heat of the afternoon may help prevent scorching.
While dame’s rocket’s white and purple flowers are lovely, this is an invasive species. Remove seed pods before they spring open to prevent an invasive nature spreading to the rest of your landscape.
- Common Pests
Flea beetles find the dame’s rocket flower and stems to be delicious treats. Use a pyrethrin or spinosad-based spray to kill these off, and neem oil to prevent them.
Snails and slugs will nibble on the lance shaped opposite leaves. An organic snail and slug bait keeps them away.
- Common Diseases
Powdery mildew is not uncommon on dame’s rocket. Neem oil is both a preventative and a treatment for this annoying problem. In severe cases, you may find it easier to burn infested areas. Only attempt this if all subsequent plantings have powdery mildew.
III. Uses and Benefits
- Ornamental uses
Dame’s rocket is an attractive and fragrant garden ornamental, ideal for cottage and wildflower gardens, especially as a border plant. This flowering plant will attract wildlife and beneficial pollinators to your garden. It spreads quite easily, and conveniently self-seeds into a variety of colors continually.
- Culinary uses
Young leaves are high in vitamin C, slightly bitter, and can be eaten in salads or cooked. They are available in the winter months in temperate climates, when few other greens are available. The tender shoots of the plant during the spring-time, when cooked, are considered an excellent vegetable. The flower buds are eaten as well, and the flowers used for their spicy flavor and bright color. Additionally, the seeds of the plant can be sprouted and eaten in salads.
IV. Dame’s rocket varieties
Hesperis matronalis comes in many varieties. Three of them are particularly noteworthy, and they are the most popular among gardeners. The basic cultivar of this plant develops lilac flowers. This variety is the most common in gardens. The two other ones are:
- Alba – a popular white dame’s rocket with flowers in this color,
- Alba Plena – another variety with white flowers, but with fuller and more impressive fluorescence.
