This charming little plant lives on the edge of two worlds. You could see it as a succulent plant, as it does indeed store moisture in its organs for survival during hard times, yet it is also a bulbous plant or geophyte, with a definite bulb.
That said, bulbs are usually underground organs, but not this one!
Silver squill belongs to the Asparagaceae family. It’s a close relative of the squills many of us grow in our home gardens (Scilla spp.). You may know, for example, the blue-flowered spring bulb, Siberian squill (Scilla siberica), widely grown in temperate climates.
In fact, silver squill was first described botanically as Scilla socialis by English botanist John Gilbert Baker in 1870. However, the name was changed to Ledebouria socialis in 1970 after a revision of the genus Scilla moved a group of mostly African species to their own genus. The new genus contains 39 species of Ledebouria from South Africa, with others spread across Africa, India and Madagascar. The new genus was named for Carl Friedrich von Ledebour (1786–1851), a German-Estonian botanist.
As for the epithet socialis, it refers to the plant’s habit of growing in dense colonies. It makes a charming groundcover in semi-arid tropical climates, for example.
You may also see this plant with the label S. violacea or L. violacea. That’s because silver squill is highly variable in the wild and some botanists thought one form with purple leaf undersides different enough to form its own species. Most now include it in the basic species L. socialis.
Found in the wild in a wide rang of soils, from rich to poor, acid to alkaline and stony to sandy and loamy, it’s a plant of the transition zone between the Eastern and Western Cape in South Africa. You’ll find it in shady spots in the evergreen forest and under scrub vegetation in drier sites. It is very widely distributed and the most common of all the ledebourias.
The local climate is frost-free or only rarely touched by frost, but winters are still distinctly cool, especially at night. The climate is semi-arid. In the wild, silver squill blooms early summer (October or November) after a rainy winter. If the winter rains fail, it can lose its leaves and remain dormant for several years until the rains return.
We grow silver squill for its foliage and bulbs. The bulbs are usually red to purple, tear-shaped, and, as mentioned, borne aboveground or with just their base covered. Each produces to 3 to 5 leaves. The leaves are most often lance-shaped to triangular, 2 ¾ inches (5 to 7 cm) long and ½ to ¾ inch (1 to 1.5 cm) wide. They can be green to silvery above with green to brown spots on the upper side. The underside of the leaf varies from green to purple. Silvery varieties with purple undersides (often called ‘Violacea’) dominate in our plant collections.
You’d expect a squill to have attractive flowers, but silver squill will certainly disappoint you.
The flowers are at best curious. Perhaps attractive enough if studied closeup, but certainly nothing to write home about. First, they are tiny, about 1/8 inch (4 mm), with 10 to 30 florets spaced well apart on an upright or arching stalk up to 10 inches (25 cm) tall. The hanging bell-shaped flowers are not very strikingly colored. They are mostly green with white or pink highlights. Stamens add more color with yellow and sometimes purple. But you need a magnifying glass to really notice!
In general, silver squill blooms in late spring or early summer, whenever that is in your climate.
Flowering is followed by green seed capsules that release small, black, glossy seeds.
You occasionally see other ledebourias on offer in succulent nurseries. Cooper’s false squill (Ledebouria cooperi, syn. Scilla cooperi), with red-veined green leaves and attractive pink flowers, is one such species. Galpiin’s false squill (L. galpinii, syn. S. galpinii) is another one with pink flowers and this time, curiously pitted leaves.
Mostly, though, any ledebouria you see in nurseries will be L. socialis or variants of that species.
As mentioned, the most common form is one some experts are calling Ledebouria socialis ‘Violacea’, with purple-backed leaves that are silver above with green spots. This is not an official cultivar name, but may become one eventually. This is the common silver squill seen everywhere.
‘Variegata’, also labeled ‘Juda’, bears a margin of white or pink on each leaf, with sometimes a variegated central stripe. You can find it quite readily if you do a bit of research online.
Growing Silver Squill
It’s an easy plant to grow, adapting to most indoor gardening conditions. So, you can treat it like a standard, tropical houseplant and it will do fine, but also give it harsh growing conditions, with a winter-long drought, like a succulent, and it will do just as well. Here are some details to guide you.
Indoors, full sun, such is right in front of a south or west window, will give denser, more attractive plants, although moderate light is quite acceptable. Outdoors—and this plant can be used as a groundcover or rock garden plant in tropical climates—, some shade is preferable. Houseplant silver squills will appreciate a summer outdoors once temperatures are above 60°F (15°C).
You can water silver squill abundantly and thoroughly in the spring and summer, whenever the soil dries out, like a typical houseplant. But you can also let it dry out deeply between waterings like a succulent. You choose!
In the winter, though, you really need to keep this plant dry, at least if you want to see flowers. That could be either mean waiting 2 weeks or so after it feels dry to the touch before watering, or not watering it at all over the winter. Pick up with regular waterings as days become longer in the spring.
(You might want to read the article 5 Simple Rules for Watering Succulent Houseplants.)
If you plan to travel, just let your silver squill cope on its own. Even if it dries out and loses all its leaves due to lack of water, it will grow new ones when watered again.
Although it comes from a fairly arid climate, silver squill tolerates both humid and dry air.
Fertilize lightly during the spring and summer. Any fertilizer will suffice.
Typical cool to hot indoor temperatures are fine from spring through fall. Keep distinctly cool in the winter, down to 41 °F (5 °C) at night. It can tolerate a light frost, down to -4°F (-1°C), especially if it is fairly dry, but why risk it?
This shallow-rooted plant is not one that requires a deep pot. There are half pots, also called tubs, which, though hard to find, that would suit it perfectly.
The nature of this plant is to fill its pot with offsets. When the pot is full, you can either break up the clump that has formed, replanting the bulbs with only the lower 1/3 of the base covered, or repotting the whole clump into a bigger pot. Good drainage is vital, so you need a pot with drainage holes and a well-drained soil. Most succulent mixes fill that bill, but then, so do standard potting mixes! You choose!
Remove drying leaves, paper-dry tunics from bulbs and faded flowers.
Usually done by division in spring, but you can also divide it at other seasons if you’re careful not to overwater afterwards. Or remove bulbs and barely push their base into a pot of growing mix. Keep these dry at first, until there are signs of rooting.
You can grow silver squill from seeds as well. Just barely cover the seeds and keep warm, moist and well lit. Germination takes about 2 to 3 weeks. Grow the seedlings under fairly humid conditions until they are well established. (Think “vegetable”!) Expect the first blooms in 2 to 3 years.
Infrequent, but mealybugs and scale insects are possible, as are aphids and thrips.
This plant is often classified as poisonous in Europe and North American publications, but apparently this is based on a belief that may not be true.
Silver squill was long considered closely related to the highly toxic blue squill (formerly Scilla natalensis, now Merwilla plumbea) and thus put into the toxic category. However, we now know they are actually quite distant relatives and now belong to two different genera. It is interesting to note that no cases of poisoning have ever been documented for silver squill, nor is it considered toxic in its native South Africa. As a result, there is considerable doubt about the toxicity of this plant.
Until things clear up, it would probably be best to consider it as being of unknown toxicity. So, keep it out of reach of children or pets.