Dames Rocket: A Merrie Olde Gillyflower

Sometimes considered invasive, dames rocket can be grown as a very effective flowering plant. Our growing guide explains how to contain it!

Dames rocket

Contents

Dame’s rocket, sometimes called dames 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. Dames rockets are considered invasive plants.

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

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Quick Care Guide

Dames rocket
Dame’s rocket in a field. Source: Spherical Bull
Common Name(s) Dame’s rocket, sweet rocket, dame’s gilliflower, rogue’s gilliflower, summer lilac, winter gilliflower, damask violet, etc
Scientific NameHesperis matronalis
FamilyBrassicaceae, the mustard family
Height & Spread1′-4′ tall and about 18″ wide
LightFull sun to partial shade
SoilWell-draining, tolerant of poor soils
WaterAbout 1″ per week
Pests & DiseasesFlea beetles, snails, slugs, powdery mildew

All About Hesperis Matronalis

Purple dames rocket flowers
Dame’s rocket is often mistaken as a native phlox, but only has four petals instead of five petals. Source: tdlucas5000

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.

Technically speaking, it’s 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.

Rapidly branching, dame’s rocket can spring up to a height of around 3-4 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 of plants, but remain smooth-edged higher on the plant’s 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.

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 dames violet.

Dame’s rocket is similar to several other plants, like garlic mustard and phlox. However, there are some prominent differences between our topic here and Phlox paniculata and garlic mustard. Garlic mustard also has some distinctly garlicly 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.

Dame’s Rocket Care

White flower stalks
While dame’s rocket is beautiful, it is an invasive species. Source: Stephen Downes

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 & 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

Multicolored dames rocket flowers
Some cultivars of dames violet have multicolored flowers. Source: milesizz

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 Dame’s Rocket

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. 

Dame’s Rocket 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.

Pruning Dame’s Rocket

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.

Troubleshooting

Hesperis matronalis white flowers
Four-petaled hesperis matronalis may appear in white or purple. Source: jon.hayes

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’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. 

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.

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.

Frequently Asked Questions

Queens gillyflower
The tall stalks of the “queen’s gillyflower” can reach as high as 4 feet. Source: lunamurphy

Q: How does Dame’s rocket spread?

A: When the seed pods open, the seeds spill onto the ground around the plant. They may be carried elsewhere in the fur of animals who pass by.

Q: Is hesperis matronalis edible?

A: Yes, the flowers and the plant are both edible, but can be slightly bitter to taste. The leaves and pods can be used as herbs while the flower is used in many dishes including salads.

Q: Are dames rocket invasive?

A: Yes. The plant is classed as an invasive species in 11 US states, primarily in the midwest and north east, with Colorado as one exception. Therefore, don’t plant dame’s rocket in the ground in these states where they’ll push out native plants, and deadhead spent blooms where you grow it.

Q: Is Dames rocket the same as phlox?

A: No, they are different plants with some superficial botanical similarities. Native Phlox paniculata has five petals, whereas dame’s rocket has four petals. Not only is there a five petals difference, their leaves diverge as well.

Q: Should I remove Dames Rocket?

A: It depends where you live. If you’re in one of the 11 states where dames rockets are invasive plants, removing it does a service to the ecosystem as a whole. Elsewhere, it may not do as much damage, but may spread and crowd out natives like many invasive plants do.

Q: Is Dames Rocket annual or perennial?

A: This plant is a biennial or a tender perennial, depending on where it is grown.

Q: Does dames rocket bloom every year?

A: It does! While it may die back in winter, it will grow again in early spring and bloom.

Q: Does dames rocket bloom all summer?

A: The long blooming period of dame’s rocket typically lasts from May to August.

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