We often think of spring as the season for bulbs, but these very useful plants can make a striking contribution to the garden at other times of year as well.
Alliums, appearing in early summer, are the beloved darlings of every Chelsea Flower Show in recent memory. And with good reason as they are elegant, colourful and provide a wonderful contrast of form to the larger shapes of roses and perennials, the spikes of iris and phormiums that are used in the display gardens. The Ellerslie Flower Show and other garden festivals in New Zealand have their own share of alliums.
Suited to modern and traditional planting styles, the deep colours of some of the hybrids add depth to colour schemes. They will hold attention long after they have faded, the structural seed heads standing tall, adding to the planting scheme.
Far too ornamental to remain in the vegetable garden, the onion family are a wonderful addition to the summer garden. Even before they flower the hooded buds of the flowers are striking, particularly on the taller varieties.
There are well over 500 different allium species, although gardeners grow only a few of these and some of the remainder are so invasive as to be unsuited to the border. Alliums combine wonderfully with old roses, with silver leaved plants and with the lime-green tones of Alchemilla mollis. Grow it in well drained soils to keep it through the winter.
Beth Chatto has made a stunning combination of Allium hollandicum 'Purple Sensation' with lovely apricot bearded iris, flushed with maroon, in her famous gravel garden. Try them also with glaucous foliage which will show off the lilac and deeper maroon tones of the alliums, below we show them with the new sedum foliage.
One of the smallest members of the family are chives, Allium schoenoprasum, a great edging plant in the potager or rose garden, they have small pinkish-mauve flowers over quite a long period, and they help to deter pests and have culinary uses as well! Cutting the leaves for use in the kitchen has the benefit of encouraging new growth.
Allium cristophii (syn. A. albopilosum) flower in early summer, timing their appearance perfectly to coincide with the old roses that they complement so beautifully. A. cristophii is one of the largest allium flowers, at some 20cm across made of larger, almost spiky starflowers. Coming from the rocky hillsides of Turkey and into central Asia, a well-drained, warm site is essential.
Spiky, wonderful A. schubertii is quite low growing, with loose, open flower heads that are simply stunning. Quite difficult to obtain, you need to visit a specialist for this particular treasure.
A. giganteum is, as its name suggests, very tall, growing to 1.5m (4ft). It needs a sheltered position protected from strong winds if you are to enjoy it for long! The flowerheads are pale lilac in a tightly packed, round globe, and white forms are available. Coming from Central Asia it likes a fertile and moist, but well drained, soil and can be propagated from seed when ripe or offsets taken in the autumn. If frosts threatened in spring protect the new foliage as they can easily be damaged.
A. karataviense, although not often found, is low growing and is easy to grow in a hot sunny position, similar to its home in limestone screes of its native central Asia.
A. hollandicum (syn. A. aflatunese) is a robust plant with smaller, deep lilac with a tighter mass of flowers; the flower head is about 10cm across. Growing to 70cm to 1.0m it is a good plant for the middle of the border and associates particularly well with roses and herbaceous plants. The form, A. hollandicum 'Purple Sensation' is a deep, magenta-purple and very covetable. A. hollandicum will happily self seed, so take care that you dead-head if you do not want volunteers in your borders.
A. sphaerocephalon is a European species with deep maroon-red flowerheads that differ from the normal globular shape, being a more pointed. Growing to about 30cm it is a useful contrast with silver leaved plants and in the herbaceous border.
A. caeruleum (syn. A. azureum) is a more unusual variety with blue flowers in a tight, rather small, 4cm flower head in mid-summer.
Lastly, the 'Golden Allium', A. moly is a clump forming plant with bright golden heads of up to 30 flowers in summer. Only 15- 25 cm tall, it is a great front of border plant but take care, as it can become invasive its many offsets quickly colonising in a suitable site. It enjoys a shady position and is especially useful in a woodland scheme.
When placing the plants in your scheme, remember that the leaves, while attractive enough when they first emerge, can look untidy later in the season. With those alliums originating in hot climates this can mean that the leaves begin to look scruffy as the plant comes into flower. Planting your alliums behind a shrubby lavender, box hedges or later developing perennials can help to screen the leaves.
There are many lovely hybrids to try. 'Lucy Ball' is delightful and easy and will increase so that you have enough for a good display and will rarely mysteriously disappear in your garden over the winter. 'Purple Sensation' is a must, albeit expensive and slower to multiply.
There are so many garden-worthy alliums, it is worth looking in the catalogues and plant nurseries to see what treasures you can turn up.
Allium cristophii
Alliums, the darlings of Chelsea
Alliums with apricot bearded iris at the Beth Chatto Garden
Cultivation Most alliums will grow well in a sunny position with a well drained fertile soil and adequate moisture. Alliums are happy in both temperate and subtropical climates making them suited to almost any region of New Zealand. Care should be taken in warmer climates that more invasive species do not swamp more desirable plants or become a pest in the wild.
Plant out bulbs, as soon as they arrive, in the autumn. Larger bulbs should be planted about 10cm deep, smaller varieties to about 5cm.
Propagation From seed as it ripens or from bulb offsets taken in autumn. Plant out bulbs, new divisions or seedlings in autumn. Seed grown plants of the larger alliums will take three to four years to flower.
Spiky, wonderful Allium schubertii
Allium giganteum is very tall
Allium h. 'Purple Sensation' works well with glaucous foliage, here Sedum spectabile
Spiky, wonderful Allium schubertii
Allium giganteum is very tall
Allium h. 'Purple Sensation' works well with glaucous foliage, here Sedum spectabile
Allium h. 'Purple Sensation'
Low growing Allium karataviense
