The mustard family, Brassicaceae, is one of our most well-known plant families, owing to the edible crops, or brassicas, we love to grow to eat. These include cabbages, cauliflower, broccoli and kale, as well as radish and turnip. But did you know there were many ornamental plants in this family, too?
Most plants in the Brassicaceae family are herbaceous plants, but there are a few shrubs. Typically, they have cross-shaped, or cruciform, flowers with four petals and two long and two short stamens. These develop into pod-like fruits called a silique, which eventually partially disintegrate, leaving the seeds held in a translucent case. Most brassicaceae seed pods are oblong, as with radish and rocket, but some are disc-shaped, like honesty.
Another way to identify plants in the Brassicaceae family is by crushing the leaves and smelling them, they all have a distinct and familiar ‘mustard-like’ smell. Like their cabbage and broccoli cousins, all brassicas prefer alkaline soils and are susceptible to the disease club root.
Here are some popular members of the Brassicaceae family.
Candytuft, Iberis sempervirens
Candytuft is a cheery annual, often used to fill gaps in the border or in container displays. It bears summer flowers in pink, purple and white, which are very attractive to hoverflies. Grow in moist but well-drained soil in full sun to partial shade.
Height x Spread 20 x 30cm
White flowers of candytuft, Iberis sempervirens
Honesty, Lunaria annua
Honesty is best known for its translucent, papery seed cases rather than its white or purple flowers. Biennial, it develops a large taproot and doesn’t like being moved – if sowing in pots make sure you plant out before the root gets too big. Grow in moist, alkaline soil in sun or partial shade.
H x S 90 x 30cm
Purple-pink flowers and purple-bronze seedpods of honesty, Lunaria annua
Sweet rocket, Hesperis matronalis
Sweet rocket bears clusters of fragrant, pale lilac flowers from late spring to early summer, which fill the air with scent in the evening. Grow in moist soil, in sun or partial shade. Deadhead regularly to prolong flowering but allow some seeds to develop as it readily self seeds.
H x S 90 x 50cm
Lilac sweet rocket flowers, Hesperis matronalis
Sea kale, Crambe maritima
Sea kale is known by a variety of names, including scurvy grass. Traditionally it was pickled to be eaten for long sea voyages and used to prevent scurvy. Its roots, leaves and fragrant flowers are edible, but these days it’s also grown for its ornamental value. Grow from thongs (root cuttings) in moist but well-drained soil.
H x S 75 x 60cm
White-flowering sea kale, Crambe maritima, growing beside pink thrift flowers, Armeria maritima
Night-scented stock, Matthiola longipetala
Night-scented stock bears wonderfully fragrant flowers, which open in the evening. Grow it close to the house or near a bench or window, where you can appreciate its scent. The flowers are edible and may be candied, for decorating cakes.
H x S 40 x 30cm
Purple-pink, delicate flowers of night-scented stock, Matthiola longipetala
Wallflowers can be biennial or perennial. Biennials bear tight clusters of fragrant yellow, orange-red, dark red, or brown flowers in early spring, while perennial wallflowers, such as Erysimum ‘Bowels’s Mauve’ bloom over a long period, but have little or no fragrance.
H x S 30 x 40cm
Golden wallflower, Erysimum cheiri
Pak choi, Brassica rapa
Pak choi is a leafy crop, bearing leaves that can be used in salads or stir fries. Best grown in partial shade and moist soil to avoid bolting. Harvest young leaves on a cut-and-come-again basis to add colour to salads, or use mature heads in stir fries.
H x S 20 x 10cm
Shepherd’s purse, Capsella bursa-pastoris
Most commonly regarded as a weed, shepherd’s purse is named after its triangular, or heart-shaped flat seed pods, which resemble a purse. It’s a small annual with pretty white flowers in spring. It bears masses of seed in summer.
H x S 30 x 20cm
White flowers and heart-shaped seedpods of shepherd’s purse, Capsella bursa-pastoris
Sweet alyssum, Alyssum maritimum
This hardy annual will quickly fill gaps in borders, bearing masses of snow-white flowers all summer long. Low-growing, sweet alyssum is perfect for rock gardens or low maintenance container displays, and can even be planted in walls and baskets where its flowers can cascade down in great clouds.
H x S 10 x 25cm
Tiny, white flowers of sweet alyssum, Alyssum maritimum
Woad, Isatis tinctoria
Dyer’s woad is a tall brassica bearing masses of bright yellow blooms on sturdy stems. It was traditionally used as a clothes dye – its leaves were harvested and soaked in water to produce a blue dye, which could be dried and used as a face paint and to colour wool and textiles. Today it makes a good wildlife plant but it’s also possible to grow and harvest your own dye.
H x S 100 x 50cm
Lime-yellow woad flowers, Isatis tinctoria
More brassicaceae plants to try
Basket-of-gold, Aurinia saxatilis
Charlock, Sinapis arvensis
Rose of Jericho, Anastatica hierochuntica
Watercress, Nasturtium officinale
Bok choy, Brassica rapa var. chinensis
Cauliflower, Brassica oleracea var. botrytis
Kohlrabi, Brassica oleracea var. gongylodes
Watercress, Nasturtium officinale