"Say ciao to the Brassicas!"

Meet an interesting plant family.
Sunday, 17 July 2022     

Vase on the desk of Tricia de Nicola in Sydney

Back in the days when my Italian lessons were held face-to-face rather than via an online platform, I recall a day when a pretty bunch of flowers on my teachers desk caught my eye as I grappled with some obscure verb conjugation. Shiny green leaves were paired with some unusual purple blooms, which at first I took for some sort of rare Camellia japonica cultivar: upon closer inspection I realised they were ornamental kale 'blooms' (actually rosettes of leaves) with some Camellia foliage added to the vase. Ornamental kale has become widely used by florists in recent times, and they last for ages in a vase. Kale belongs to the vast Brassica or mustard family (Brassicaceae, previously called Cruciferae), an interesting group of plants that contains both ornamental and edible plants; indeed, kale can be had in both forms! Both types of kale belong are classified botanically as Brassica oleracea Acephala Group.

The decorative plants within the family are rather old-fashioned flowers, long grown in English cottage gardens. Whilst not all of them flourish well in Sydney (I failed miserably with Arabis, Hesperis, Iberis, Crambe, Aubretia, Alyssum and Cardamine in my cottage garden years), some do, and I enjoy having them in my garden as a reminder of that part of my gardening journey. All have simple, four-petalled flowers that resemble a cross, which are attractive to beneficial garden insects: another great reason for growing them. One of them, a delightful shrubby perennial wallflower (Erysimum mutabile, syn. Cheiranthus mutabilis), is just starting to bloom now, and will continue all through spring. The original species (ht 80 cm, pictured above) has flowers which open pale yellow then age to mauve. The cultivar 'Winter Joy' has pretty all-mauve flowers and 'Apricot Twist' is an attractive orange-bloomed version.

These plants, hailing from the Mediterranean, enjoy a sunny, well-drained position, on the dry side, with a little lime added to the soil - in fact most members of the family seem to like a bit of lime! They need to be cut back after flowering to keep them compact, but like many such shrubby Mediterranean perennials, they will only last a few years (especially when we experience a lot of heavy rain): propagate from cuttings. These wallflowers combine well with other plants from the Mediterranean that flower at the same time, such as Iris germanica, French lavender (Lavandula dentata) and Marguerite daisies. There are biennial forms of wallflowers, which I recall grew in my parents' garden, along with the gorgeously scented biennial stock (Matthiola incana), another member of the Brassicaceae.

Often known as honesty, Lunaria annua (ht 30 cm) , is also a biennial plant from the Brassicaceae that grows well in Sydney gardens, self-seeding from year to year. The basic plant has plain green leaves with clusters of purple flowers, and is a pretty thing; however, some of the cultivars are more interesting. I like Lunaria annua var. albiflora 'Alba Variegata' (pictured above), which has white and green marbled leaves and white flowers. I grew it from seed many years ago and it still comes true from seed fairly well. The plant will grow quite well in shaded sites and doesn't need any special cosseting. It usually takes a full year to achieve flowering stature: sow the seed in spring for blooming the next year. It flowers around late September or October. The branched seed pods that follow the blooms are decorative in the garden in their own right.

An annual plant, Lobularia maritima, often known as sweet Alice or alyssum (ht 20cm), has honey-scented fragrant little bobble flowers and is another old-fashioned favourite from the Brassicaceae. Like honesty, it is a determined self-seeder. The most common form is white, but there are also pink and purple varieties. It too is a Mediterranean plant and enjoys dryish, sunny positions in the garden. It is often used as an edging plant and blooms for many months. I have an interesting form called 'Snow Princess' (pictured above), which is said be a perennial form, growing robustly to a wide mat. It can be cut back by half when it gets untidy and will regrow strongly. It has crisp white flowers all year round, with a strong scent. Another annual from the family that I used to grow was Virginian stock (Malcolmia maritima), a dainty plant with cute lilac blooms.

Brassica oleracea contains, in various other 'groups', many highly nutritious crops with many health benefits, which seem to grow best in the cooler month and broccoli. Other members of the broader Brassicaceae family include turnips, kohlrabi, radishes and swedes. Of these vegetables, I have only tried cultivating radishes (which are very easy!) but I do sow seeds of some of the easy-to-grow leafy Brassicaceae crops in my garden in winter in spots where I have big gaps, such as where my Dahlia plants are lying dormant. In general, these types like moist, fertile soil to support their rapid growth: poor soils result in bitter, tough leaves. They will all regrow after being harvested so that a number of cuts can be made; but it is a good idea to make successive sowings to ensure a long period of supply, as the plants eventually become exhausted! All of them can be grown successfully in containers. Allowing a few of the plants to progress to flowering will attract beneficial insects into the garden. Rocket (Eruca vesicaria syn. Eruca sativa), with its peppery leaves, is perhaps the best-known member of the family, being a quick-growing leafy green for salads, pesto and pasta dishes.

Edible kale has become a trendy food in recent years, and is used in salads, stir-fries and many vegetable dishes. Its many decorative forms, with curled or crinkly and/or coloured leaves of various shapes and sizes, can look most attractive in the garden. The dwarf green curly kale I have grown for the past few years (pictured above) keeps going for about 12 months before becoming woody and unproductive.

The various forms of cress are also nutritious members of the family, including true watercress (Nasturtium officinale), garden cress (Lepidium sativum, familiar to many from childhood, when it was grown on a piece of cotton wool as 'mustard and cress') and land cress (Barbarea verna). There are other leafy members of the family that are sometimes called 'Asian greens', including bok choi or pak choi, mizuna, komatsuna and tatsoi, which all seem to be 'groups' within Brassica rapa. All these plants are valuable for stir-fries and salads. Most members of the Brassicaceae family are prone to attack by the white cabbage moth. For that reason, I grow mine in a trough under a wooden frame covered in fine mesh to exclude this pest

All in all, the Brassicaceae family is an interesting and useful clan!

Blog first posted 30 July 2017; updated 17 July 2022.


 Reader Comments

1/5  Peta - 2758 (Zone:9 - Cool Temperate) Monday, 31 July 2017

I was very interested to see the gardeners planting big beds of decorative Brassicas in Hyde Park a couple of months ago. It was all being done quite seriously with chalk lines and spacing. I"ll take the camera next time I visit Sydney to check out the result. Isn"t this family useful? The white cabbage moths would definitely agree...I saw one yesterday flitting through the garden. I will also look out for that planting in Hyde Park! Cabbage moths are indeed a pest; when growing rocket etc in tubs, I place them under a large wooden frame covered with mesh to keep the moths out! Deirdre


2/5  Diane - 3788 (Zone:10 - Mediteranean) Monday, 31 July 2017

Years ago I admired beds of ornamental multi coloured kale in public gardens in Lisbon. I grew some in Melbourne which were a curiosity for passers by. But please don"t cut and bring inside unless you like the terrible cabbage smell! Yes I think the water in the vase would need frequent changing, but they do seem to me a great cut flower. Deirdre


3/5  Margaret - 2122 (Zone:10 - Warm Temperate) Tuesday, 01 August 2017

I had two beautiful ornamental cabbage plants growing in my garden, with the leaves just shading to purple, but the next day the tops were eaten out - by rat or possum? Perennial wallflowers grow successfully for me. Years ago, I bought a punnet of annual wallflowers, but these have lasted for the past 12 years or so. Admire the variegated Lunaria, I must buy some seeds. I have successfully grown cabbage, broccoli and caulis, in the past. So annoying about that kale being eaten! Interesting about the annual wallflowers lasting all those years. Such pretty flowers. Great re your success with the veggies! Deirdre


4/5  Jude - 4560 (Zone:10 - Warm Temperate) Monday, 18 July 2022

Thanks for this information, Deirdre! When I was a grad student in Toronto many years ago, our first flat was in Cabbage Town, named for its original working-class residents who wisely grew vegetables in their tiny front gardens. By the time we moved in, Cabbage Town had been thoroughly gentrified but some residents, with a nod to history, planted their gardens with sturdy, cold-resistant ornamental brassicas. A delight. Pretty and typical of the Toronto sense of humour, I always felt. I love that story. The Canadian sense of humour is fab! Deirdre


5/5  Margaret - 2122 (Zone:10 - Warm Temperate) Wednesday, 20 July 2022

An interesting array of plants in your garden, Deirdre. My garden is suffering from too much rain, at the moment, but I am pleased to say my wallflowers, mentioned in an earlier blog, are still self-seeding and growing well, in different areas of the garden. Things are not great for our gardens right now. I hope the rain stops soon. Good that your wallflowers are doing well. Deirdre


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