No, I'm not talking about those wonderful volunteer lifesavers at the beach in summer, but about some hard-working annuals from the plant world. Many are descendants of original plants I sowed 25 years ago when I first began my present garden, appearing of their own volition every spring from seeds shed the previous autumn - hence the term 'volunteers'. They have become the stars of my summer garden, giving a feel of abundance and spontaneity in borders which might otherwise have been dull and contrived.
Such happily self-seeding plants are not recommended for tidy gardeners who like to be in total control! From year to year, you'll have no idea where they will appear, and few take too kindly to being transplanted to a 'better' spot. It is a matter of culling out the seedlings that really are in the wrong location and allowing a lucky few to grow to maturity in their chosen places. Most are tough plants, which will grow in indifferent conditions, but all will respond gratefully to a little extra care. Rigorous deadheading of spent blooms is a no-no if you want subsequent generations of plants to appear! Mulching of areas where you don't want them to pop up is wise. None should be allowed to escape into bushland or pastures.
The most statuesque of these plants is often known as love-lies-bleeding (Amaranthus caudatus, ht 1 - 1.2m), which can assume the dimensions of a small shrub in a couple of months. Its plush burgundy tasselled flowers arch from the top of the rhubarb-coloured stems like a floral fountain. It brings a dramatic, tropical effect to summer and autumn borders and looks stunning with dark-leaved companions such as Alternanthera or Canna, as well as rich purple or blue flowered Salvia. A beautiful purple-leaved form (Amaranthus cruentus) exists: I am not keen on its more upright flowers but I love its foliage. Amaranthus thrives in a sunny position and can cope with dry conditions. Be sure that you are in love with it before you plant a single, tiny seed: because once you introduce it to your garden, it will be there every summer!
Another giant enjoying the same sort of growing conditions is the spider flower (Cleome hassleriana, ht 1 - 1.5m). Above bold, palmate leaves, rounded heads of whiskery pink, white or lavender blooms like friendly flower people are held on increasingly long necks as summer progresses. They provide a superb background mass of colour and exotic form over an extended period. If you tip-prune them when the seedlings are small, a more branched plant will result, with multiple blooms. I went off these annuals for a while and pulled out all my self-sown seedlings, when I became enamoured of a compact hybrid Cleome that promised to be perennial. Whilst I still enjoy this newer plant, I have gone back to Cleome hassleriana, seedlings of which luckily still kept coming up for years after I stopped intentionally growing it!
In moist, fertile soil in a sunny spot, red orach or mountain spinach (Atriplex hortensis var. rubra) may grow 1.2 - 2m tall; it will be shorter in less favourable conditions. Its sumptuous purplish-red, arrow-shaped foliage is its main attraction, the flowers being insignificant. However, when its purple seedpods develop, these are very decorative. The leaves are as effective in combination with the blue, pink or lavender flowers of a cool-coloured garden as they are with hot oranges, yellows or reds. When you tire of it, you can eat the plant's leaves in a salad!
Butterfly-attracting Verbena bonariensis (ht 1 - 1.5m) is probably quite rightly regarded as a weed by some gardeners, but few other plants have the ethereal grace of its tall skinny stems topped with dainty lilac-purple posies. It looks best at the front edge of a border, to break the monotony of low plantings without obscuring other plants behind it. It also looks effective grown with ornamental grasses to create a meadowy look. It will grow simply anywhere, in any soil, but does best in full sun. I cut mine back by half periodically through summer, which gives them a new lease of life; some plants survive through winter, but there are also plenty of new seedlings each year.
In more recent years, several self-seeding annuals from the Apiaceae family have entered my garden. Ammi majus, a form of Queen Anne's lace, is a hardy annual from Southern Europe, Turkey and North Africa with fern-like leaves, which can provide a romantic cottagey effect in Sydney gardens. Statuesque plants, to 1.2 m in height, they bloom for a number of weeks in late spring and early summer, with broad slightly domed heads comprised of many clusters of hundreds of miniscule white flowers, each cluster held on stalks of different lengths that come out from a common point on the main stem. Within each little cluster, individual flowers are held in that same domed shape, the overall effect being like an intricate lace parasol! The flowers seem to float in the border, swaying gently with every breeze. They appreciate moist but well-drained soil in a sunny spot. In the first year I had them, when I planted them in spring, they flowered well into summer, but when they started self-seeding, they germinated much earlier (in autumn) and the flowers appeared in mid-spring, continuing into early summer. For blooms in mid-late summer, I suggest planting the seeds in September.
A related plant, new to me this year, is Daucus carota 'Purple Kisses' (ht 110 cm), sometimes known as 'chocolate Queen Anne's lace'. The tiny clustered flowers on my plant are a soft pink, but they can vary from pink to purple, crimson and deep burgundy, or even near-black. It seems to behave like Ammi majus, being quite flexible about when it will grow. My friends who planted the seeds in autumn, had flowers in November, whereas mine, sown in spring, are flowering now. The flowers are quite beautiful. Like Ammi majus, it likes sun and good drainage, and it is a good cut flower
Take a chance on one or more of these annuals next summer!
Blog first posted on 16 January 2010; updated 24 January 2021.
Tall summer volunteers
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These will provide colour and form in your garden every summer.
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Zucchini can be a rewarding summer crop.
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Lots of plants caught my eye on a walk.
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Cut flowers for Christmas vases