Gardens

RHS Garden Hyde Hall

Plant of the Month May

             

Allium schubertii @ Hyde Hall

RHS Garden Hyde Hall holds the National Collection of viburnums and many of these are grown in a mixed planting opposite the Shrub Rose Border in the Hilltop Garden. We have underplanted many of the shrubs with lower growing perennials and also swathes of spring bulbs such as narcissus. To extend this season of colour into early summer we have also used several species of Allium and one that stands out as an excellent selection is Allium schubertii with its distinct star-shaped flowers borne on stalks of different length. As this Allium naturalises it makes a wonderful underplanting beneath the taller shrubs and hides their bare lower stems.

Allium

The name Allium is from the ancient name for garlic, which is part of the genus. There are estimated to be around 700 species within the genus, and many cultivars. There are perennials and biennials, ranging in height from 10cm (4in) to 150cm (5ft) or more.

They are mainly from dry and mountainous areas, all from the Northern Hemisphere, and they have adapted to live in almost every plant habitat on the planet, from ice cold tundra to burning, arid deserts.

Many members of the genus give themselves away with the distinctive smell of onions when the bulb or foliage is bruised.

They have upright to spreading linear shaped leaves. The tubular based flowers are bell, star or cup shaped which are borne in spherical umbels 1cm (3/8in) to 10cm (4in) across.

In most species, a single bulb produces clusters of offset bulbs around it, which gradually form clumps.

Taller species look good in groups in a border. The flower heads dry well.

Several species have culinary uses, including A. sativum (garlic), culinary onions, shallots and chives.

The whole group was prized by the ancients as possessing medical and aphrodisiac qualities as well as flavour. The Romans are sometimes held responsible for their wide distribution by taking them wherever they went.

Allium schubertii

This onion relative is native to eastern Mediterranean to Central Asia. With ribbed grey-green strap like leaves emerge from the bulb and grow to 40cm (16in) long before dying back in early summer and giving way to flowers. The characteristic ‘lollipop’ shape flowers are 30cm (12in) across with approximately 50 tiny pale purple flowers clustered together on stalks of varying lengths. It has one of the largest flowers of all the alliums. When the flowers appear in early summer they take on a metallic sheen and have been likened to an exploding firework.

Flower stalks dry well and can be used in arrangements or they can be left outside to provide winter interest as they look good covered in frost.

Contact with bulbs may irritate skin.

Cultivation

Grow in fertile, well-drained soil in full sun. Plant bulbs 5-10cm (2-4in) deep in autumn.

Plant clump forming species with rhizomes at or just below the soil surface in spring.

Alliums are susceptible to white rot, downy mildew and onion fly.

Propagation

Propagate by offsets, removed when dormant or by seed in spring at about 13°C (55°F). Keep moist and well ventilated, and dry progressively as foliage dies back. Prick out and pot on when dormant. Seed grown plants, however, may not come true from seed.