How to Plant, Grow, and Care for Dame’s Rocket

Dame’s rocket, sometimes called dame’s violet or dame’s gilliflower, is an attractive herbaceous plant with lovely flowers. Popular for centuries, this plant is among the many chronicled in John Gerard’s “The Herball or Generall Historie of Plantes”, originally published in 1597:

“Dames Violets or Queenes Gilloflowers, hath great large leaves of a darke greene colour, somewhat snipt about the edges; among which spring up stalkes of the height of two cubites, set with such like leaves; the flowers come foorth at the toppe of the braunches, of a faire purple colour verie like those of the stocke Gilloflowers, of a verie sweete smell, after which come up little long cods, wherein is conteined small long blackish seed. The roote is slender and threddie. The Queenes white Gilloflowers are like the last before remembred, saving that this plant bringeth foorth faire white flowers, and the other purple. They are sowen in gardens for the beautie of their flowers. They especially flower in Maie and June, the second yeere after they be sowen.”

But many plants which are beautiful and popular are also difficult, and dame’s rocket is no different. This species is fast-spreading, and quickly naturalizes in meadows and woodlands. Dame’s rocket is considered invasive.

Let’s talk about this merrie olde plante in more detail. If you keep it in check, you can enjoy the “Queenes gilloflowers” too!

What is Dame’s Rocket

Technically speaking, Hesperis matronalis is a tender perennial or a biennial. This species survives usually for two years. In its first year, it develops its structure and foliage, its roots spreading out beneath the soil. But in its second year it begins to bloom, and it easily self-sows during that year. Any plants that survive for a third year will also be able to bloom.

In this way, once it’s become established in a garden, you’ll see pretty flowers every year. On warm days, the plant produces a sweet and unique aroma that becomes stronger towards the evening. This fragrance is appealing and part of the popularity of the plant.

Native Area

Among native plants from Europe and Asia, dame’s rocket has spread from woodland edges to the rest of world. It’s often seen here in North America as both a garden annual and a wildflower.

Hesperis matronalis has many common names, ranging from the queen’s gilliflower (as described by John Gerard) to other terms. Rogue’s gilliflower, mother-of-the-evening, damask violet, summer lilac, and many other names have been applied to these plants. But most commonly, it’s referred to as dame’s rocket or dame’s violet.

Characteristics

Rapidly branching, dame’s rocket can spring up to a height of around three to four feet and spread to about 18 inches wide. The opposite leaves have toothed margins and form on short stalks. Lance-shaped, these opposite leaves can develop a slightly toothed edge towards the base but remain smooth-edged higher on the stem.

The lance-shaped leaves also have another side benefit. While slightly bitter, they are edible. This is likely part of where the term “rocket” began to be applied to H. matronalis. Arugula is a related species, and as it’s also referred to as rocket the name likely originated there.

Blooming occurs from late spring into summer, most commonly in May and June. It’s a short period during which purple or white four-petaled blossoms appear. Similar in appearance to phlox (which has five petals instead of four), these rocket flowers are roughly a half-inch in diameter and create a riot of color across the plant. Some cultivated forms produce double-layered flowers, but most are a single four-petaled flower.

This member of the mustard family develops four-inch seed pods filled with pitted brown seeds. When the pods dry, they easily break open to set seed onto the ground. Its root system is shallow, comprised of a taproot surrounded by a tangle of rough secondary roots.

Dame’s rocket resembles several other plants, like garlic mustard and phlox. However, there are some prominent differences between our topic and Phlox paniculata and garlic mustard. Garlic mustard also has some distinctly garlicky leaves. Crush one to identify whether or not it’s a dame’s rocket.

Is Dame’s Rocket Invasive?

The growth habits of dame’s rocket have been described as “explosive”, and it is classed as an invasive species in 11 US states. While it doesn’t laterally spread, the self-sowing seeds should be removed before they fully dry to prevent further development. This prevents dame’s rocket from outcompeting native plants and native wildflowers which support native insects.

The easiest way to stop its spread and overtaking of regional native plants is to deadhead spent blooms before they start to form those pods. But you’ll have to look closely, as it can still be flowering while forming seed pods!

If it’s already begun to take over, you’ll need to remove the entire taproot to prevent an invading rocket plant from growing back. While the rest of the root system is easy to remove, that taproot can get quite deep, so be prepared to do a bit of digging if it gets out of hand. Conservationists sometimes burn infested areas to control its spread.

Planting

To plant dame’s rocket choose a sunny or partially shaded location with well-draining, fertile soil. This plant prefers a slightly alkaline pH, so you may wish to amend acidic soils with lime if necessary. Start seeds directly outdoors in early spring or fall, as the seeds require a period of cold to germinate.

Sow the seeds about a quarter-inch deep, spaced at least 12-18 inches apart, as the plants can spread and reach up to four feet tall. Water the area gently to keep the soil moist but not soggy until germination, which usually takes about two to three weeks. Once established, it’s quite hardy and needs minimal maintenance, though removing spent flowers will help control its spread, as it can reseed prolifically.

How to Grow

Other than being a bit on the invasive side, dame’s rocket is surprisingly easy to care for. Let’s go over the best conditions to guarantee success!

Light

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. Whenever possible, aim for a minimum of six hours of sun. If it’s not scorching hot, longer is preferred.

Water

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 typically 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 best in a blend of sandy 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. 

Temperature

It grows well in zones 3-9. Much of North America falls into the dame’s rocket-growing range! 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°F (21-29°C) for best growth.

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. 

Maintenance

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°F (21-29°C) soil temperature range to germinate.

While it is possible to grow dame’s rocket from stem cuttings, they don’t root particularly well. The use of a rooting hormone may help them to produce better roots. Rooting hormone is widely available in garden shops across the United States.

Common Problems

It grows like a weed, so keeping it alive isn’t your major concern. But what about keeping it healthy? Let’s talk about what few difficulties may arise.

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 white and purple flowers are lovely, this is an invasive species. Remove seed pods before they spring open to prevent an invasive nature from spreading to the rest of your landscape. 

Pests

Flea beetles find the dame’s rocket flower and stems to be delicious treats. Use 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.

Diseases

Powdery mildew is not uncommon on dame’s rocket. Remove mildewed leaves at first. 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.

Frequently Asked Questions