Scilla is a lovely genus of bulbs, with species flowering from late winter until early summer.
They are most known for their contribution to the spring display with those lovely blue accents, but there are actually flowers in shades of white, pink and purple too. Until quite recently the English and Spanish bluebells were included — no longer, now they stand alone reclassified as Hyacinthoides non-scripta and Hyacinthoides hispanica, but you can see the similarities.
It is a large genus of around 90 species in South Africa, Asia and Europe. Their flowers vary from being open and star-shaped to nodding and bell-shaped like bluebells — S. siberica Award of Garden Merit (AGM), for example. They are borne on upright stems above strap-shaped leaves, sometimes quite a time before the flowers — S. liliohyacinthus — but other times together.
The dwarf early-flowering varieties start opening in February. These include the gentian-blue
S. bifolia AGM and pale-blue S. mischtschenkoana AGM. The tough Siberian squill, S. siberica AGM, is a bit taller, with nodding violet-blue bell blooms and flowers later, from March to April.
Some taller types flower in early summer, including the dramatic S. peruviana, with large dense flower heads on 30cm-tall stems, and the elegant S. litardierei AGM with its lilac-blue flowers.
S. bifolia AGM and S. siberica AGM can be naturalised in short grass. Others such as S. mischtschenkoana AGM prefer better drainage, but they can be tried in tree circles where they light the dark space beneath the canopy beautifully. The diminutive species are also great subjects for the rock garden and can be grown in pots in the alpine house, where they can be fully shown off.
S. messeniaca, along with the adaptable S. bifolia AGM, thrive in the partial shade under shrubs so can be used in borders. S peruviana looks like a half-hardy exotic but it is actually hardy down to -5°C and can be planted outside. South African species, which often have attractive foliage, do need the protection of a glasshouse in winter.
But the garden types are all hardy, and cope down to at least -10°C. Scilla bulbs will deteriorate quickly when out of the soil so they should be planted quickly after purchase. They like a freely draining humus-rich soil in sun or partial shade. S. siberica AGM has a preference for rich, sandy soils and will form large clumps.
What the specialists say
Chris Ireland-Jones, owner, Avon Bulbs, Somerset
"Many of the smaller scilla — S. bifolia and S. siberica in particular — are useful in providing that important backdrop to the other bigger bulbs in one’s display. They are the chorus to the main performance, along with the other small blue bulbs — anemone, Puschkinia, chionodoxa, Muscari and the myosotis (forget-me-nots). Most are individually very inexpensive and can be used en masse.
"The early-flowering S. mischtschenkoana is unpronounceable and sadly a little more expensive but very early-flowering indeed, with the palest blue blooms — very pretty with Cyclamen coum or nestling among the black-leaved Ophiopogon nigrescens.
"The individually more impressive S. peruviana seems to require a hot summer the previous year to flower well the following spring, but they are much admired with architectural flower heads that seem to swirl outwards from the centre. Their leaves are wide, shiny and strap-like. However, in years when the bulbs do not flower they can be viewed as being a bit frustrating."
John Amand, managing director, Jacques Amand, Middlesex
"Scilla are very useful in the garden, especially the low-growing forms that come after the snowdrops and with chionodoxa. They come back every year and are no hassle. You can plant daffodils in between.
"In terms of species, S. siberica is the common one. You can’t knock it — it’s a lovely little blue bulb.
S. mischtschenkoana is very nice too, with its pale-blue almost creamy flowers. I also like S. autumnalis and S. bifolia.
"If you want a taller bulb go for S. hyacinthoides. It can reach about two-and-a-half feet, sometimes three, and flowers in April to May. If you want something a little more special grow S. peruviana, which is a stunning plant. It can be grown in a pot and kept in an alpine house, though flower colour is not shown at its best indoors. They look best grown outside. They can cope with temperatures down to -5/6°C though will suffer in tough winters that see conditions down to -14°C. I personally do not care for the white form. I much prefer the blue.
"Scilla are not difficult to establish at all. They grow in any old soil. I prefer them planted in borders or tree circles rather than in grass."
Kit Strange, horticulturist, Royal Botanic Gardens, Kew
"The scilla collection at Kew is mainly pot-grown. The bulbs are repotted every year, ideally in September or October. Any later and the bulbs will have roots on.
"They are all potted into terracotta pots in Kew mix 2, which is like a John Innes No 2, so quite loamy. They are then plunged in sand and watered in, and the roots start to grow straight away. In the time between them being potted and coming up you just water the sand. Limit the watering until you see them breaking the surface, then you can water freely.
"If grown in plastic pots just one water will be okay until they come up. Then keep them well watered until May/June, when they will go to sleep again. Do not water them in summer or put them somewhere hot when they are dormant — they do not want to be cooked. Then in September you start all over again."
Species and varieties
S. autumnalis is a species that flowers in the late summertime and early autumn. It has dense racemes of small purple flowers that appear before the linear leaves. Height: 25cm.
S. bifolia AGM (H5) is an early-flowering, dwarf species with deep gentian blue, starry flowers over waxy leaves. Flowers February-March. It is easy to grow and will naturalise under shrubs or in light grass. Height: 10cm.
S. liliohyacinthus — or the Pyrenean squill — is a good bulb for the woodland that produces broad, fleshy leaves in early winter, followed by lovely pyramidal heads of sky-blue flowers in late April. Plant in cool, humus-rich soil in partial shade, though it can cope with sun too. Height: 15cm.
S. litardierei AGM (H5) is a very pretty plant with a dense spike of open, star-shaped, violet-blue flowers in early summer. Grow in sun or partial shade and in well-drained soil. Height: 10-20cm.
? S. mischtschenkoana ‘Tubergeniana’ AGM (H5) is a low-growing, early bulb, sometimes still referred to as S. ‘Tubergeniana’. Its flowers appear with the leaves in late winter. The flowers are lovely —
star-shaped, whitish-blue with darker central stripes and up to six flowers per stem. Easy to grow, especially in light soils. Height: 10-15cm.
S. peruviana is a dramatic specimen bulb that can be planted in the ground but also looks fabulous shown off in pots. It produces large flower heads of rich-blue, starry flowers that look good in bud and once opened, above broad fleshy leaves. Flowers May-June. They like a position in full sun. Actually from the Mediterranean, they were named after the ship they arrived in, The Peru. Height: 25-30cm.
S. siberica AGM (H5) are invaluable bulbs for the spring garden. Being from the area around the Black Sea, they are very robust and hardy. They produce striking violet-blue, nodding, bell-shaped flowers, up to five per short stem, in March and April. Their strap-shaped, mid-green leaves are slender and glossy. They will naturalise very well or can be planted into pots. Height: 15cm.
S. siberica ‘Alba’ is a white-flowered form that makes a good contrast with the blue when they are planted together. Flowers March-April. Height: 15cm.
S. siberica ‘Spring Beauty’ is a highly attractive form with vivid dark-blue flowers. Height: 15cm.
S. verna — or the spring squill — is a dwarf species that produces a dense raceme of small, starry violet-blue flowers above linear leaves in early spring. Height: 20cm.