Bulb · Asparagaceae
Siberian Squill
Scilla siberica
Plant the bulbs once and a sheet of early blue comes back every spring, all on its own.
Full sun
Every 7–14 days
USDA 2–8
3–6 in · 8–15 cm
Overview
Siberian squill is one of the first bulbs to wake up the garden, opening its deep blue bells in early spring just after the snowdrops. It stays low, only 3 to 6 inches (8 to 15 cm) tall, so it works best in drifts under trees, along paths, or scattered through a lawn that won't be mowed too soon.
What makes it easy is also what makes it pushy. The bulbs are extremely cold hardy, shrugging off winters down to -40°F (-40°C), and they ask for almost nothing once planted. But squill spreads fast by self-seeding and offset bulbs, so it can slip out of the bed and into lawns and woodland, and it is treated as invasive in parts of the US.
There is a real catch to keep in mind. Every part of this plant is poisonous, the bulb most of all, so it is not a plant for a garden where pets graze or small children dig. Site it with that in mind and it pays you back with years of trouble-free color.
Care
The short version: plant the bulbs 2 to 3 inches deep in fall, give them sun to part shade and well-drained soil, water through spring growth and then leave them dry while dormant, and deadhead if you want to keep the spread in check.
Light
Squill flowers best in full sun but takes partial sun or partial shade without complaint. Since it blooms in early spring before the trees leaf out, a spot under deciduous trees still gets plenty of light when it counts.
Water
Give it medium moisture through its spring growth and bloom, then ease off once the foliage dies back. The bulbs go dormant for summer and want little to no extra water, and standing wet is the one thing that will rot them.
Soil
Average, well-drained soil is all it asks for, and it isn't fussy about pH. Sharp drainage matters far more than richness, especially over the dormant summer months.
Temperature
This is a remarkably tough bulb, hardy through zones 2 to 8 and surviving lows of -40°F (-40°C). It grows in the cool of early spring and rests once temperatures climb past about 75°F (24°C).
Humidity
Ordinary outdoor air suits it fine, so there's no humidity level to manage. What matters instead is that the soil dries out for the bulb's summer rest.
Feeding
Squill barely needs feeding in average soil. A yearly topdressing of compost or a balanced bulb fertilizer in fall or early spring is plenty, and anything more is wasted.
Pruning
There is no real pruning to do. Let the foliage die back on its own after bloom so the bulb can recharge, and only cut the spent flower heads if you want to slow its heavy self-seeding.
Repotting
Established bulbs rarely need lifting. The time to act is when bloom drops off in a crowded clump or masses of bulbs start heaving to the surface, at which point you dig and divide them.
Size & spacing
Plants stay small, just 3 to 6 inches (8 to 15 cm) tall and about as wide, which is why squill works in drifts. Set the bulbs 2 to 3 inches deep in fall and space them so they have room to multiply into a sheet of blue.
When to plant
Squill runs on a simple early-spring clock. Plant the bulbs in fall while the soil is still workable, let winter do its work, and the blue flowers open around April, right after the snowdrops fade.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Plant bulbs in fall, 2-3 inches deep
- Harvest: Blooms in early spring (around April), shortly after snowdrops
Hardiness
USDA hardiness zones: 2–8
Temperature: down to -46°C
Troubleshooting
Squill is about as low-maintenance as a bulb gets, so its few problems come down to wet soil, one bulb pest, and its own habit of spreading. Match what you see below and deal with it before a small patch becomes a takeover.
Soft, mushy bulbs and a crown that caves in
This is crown and bulb rot, and it comes from ground that stays wet rather than from any disease you can spray off. Squill bulbs hate sitting in water, especially through their summer rest. Lift the bulbs to check for soft, brown, foul-smelling tissue, throw out anything spongy, and move the planting somewhere with sharper drainage.
Fix:
- Remove and discard affected bulbs
- Improve drainage or move planting to a better-drained site
- Reduce watering, especially during dormancy
Hollowed-out bulbs and weak or missing growth
When a bulb comes up distorted or fails to grow, suspect the narcissus bulb fly. Its larva burrows in and eats out the center, leaving a hollow shell packed with frass. Cut open a suspect bulb and look for a single fat cream-colored maggot, then dig and destroy anything infested and turn the soil to expose the pupae.
Fix:
- Dig and destroy infested bulbs
- Cultivate soil to expose pupae
Squill turning up far from where you planted it
Siberian squill is an aggressive self-seeder that also multiplies by bulb offshoots, so colonies creep into lawns, beds, and nearby woods. It is treated as invasive in parts of the US. Mow or deadhead the flowers before seed sets, dig and thin crowded clumps, and keep it away from natural areas.
Fix:
- Mow or deadhead while in bloom to remove seed heads before seed sets
- Dig and thin clumps before seeds mature
- Compost removed material at temperatures above 130 degrees F
Toxicity
Treat this as a poisonous plant, not a harmless little bulb. Every part holds cardiac glycosides, with the bulb the most dangerous, and eating it can cause drooling, vomiting, and cramping, and in quantity a dangerously slowed or uneven heartbeat. Keep it away from pets, livestock, and children, and call a vet or poison control if any is swallowed.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Severe
A cat that chews any part can start drooling and vomiting within a short time. The bulb holds the most cardiac glycoside, and a real mouthful can throw the heart rhythm off, so treat it as an emergency.
Dogs Severe
Dogs usually dig up and bite the bulb, which is the most dangerous part. Expect drooling, vomiting, and diarrhea at first, with a slowed or uneven heartbeat if a lot goes down.
Horses Severe
The same cardiac glycosides act on horses, bringing colic and a sluggish, unsteady animal. A heavy dose can disturb the heartbeat, which is serious in a large grazer.
Rabbits Toxic
Squill is not safe browse for rabbits. The bulb and foliage can upset the gut and, in quantity, affect the heart, so keep the plant well out of reach.
Livestock Toxic
Cattle, sheep, and goats can be poisoned by grazing the foliage or turning up bulbs. Watch for drooling, gut upset, and an off heartbeat, and fence the patch off from pasture.
Birds Toxic
The cardiac glycosides make every part risky for birds, including backyard poultry that scratch up bulbs. Keep hens and pet birds away from the plantings.
People Caution
No part of this plant is food. Swallowing it can cause mouth pain, nausea, vomiting, and cramping, and the bulb in quantity can slow or disturb the heart, so keep curious children clear and call poison control if any is eaten.
Keep bulbs and plants away from pets and children; wear gloves when handling, as sap can cause minor skin irritation in susceptible individuals.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
There isn't a long list to learn here. Beyond the wild species, one named selection turns up most often, and the two are easy to tell apart.
Spring Beauty
It looks much like the wild species but runs a little larger, blooms longer, and carries a deeper shade of blue.
Scilla siberica (species)
The straight species sends up 3 to 4 slim scapes, each hung with 1 to 3 nodding bell-shaped deep blue flowers set off by blue anthers.
Companions
Squill pairs best with the other earliest bulbs that bloom alongside it and naturalize the same way, building a layered carpet of late-winter and early-spring color.
Plant near
Galanthus (snowdrops): Both are very early spring bulbs that bloom in sequence and naturalize well together in drifts.
Crocus: Similar early-spring bulb that can be naturalized in lawns and beds alongside squill for layered bloom.
How to propagate
Multiplying squill is almost too easy, since the plant does most of it for you. You can speed things up by splitting clumps or planting fresh bulbs, or just let it seed itself around.
Offsets & pupsEasy
Lift and separate dormant bulbs after foliage dies back · One growing season
The easiest way to make more squill is to let it do the work and then split what it builds. Once the foliage has died back and the bulbs are dormant, lift a crowded clump and pull the offset bulbs apart by hand. Replant them and they settle in within a single growing season.
Bulbs & cormsEasy
Plant bulbs 2-3 inches deep in fall · Blooms the following spring
Starting from bought bulbs is as simple as bulb planting gets. Set them 2 to 3 inches deep in fall and leave them be, and they flower the very next spring. The bulbs are tough and extremely cold hardy, so a hard winter does them no harm.
SeedEasy
Self-sows in spring as seed matures · Several years to flowering size
Squill sows itself with no help at all, dropping seed in spring as the pods ripen. That free spread is exactly what drives its aggressive naturalizing. Seedlings take several years to reach flowering size, so this is the slow route if you actually want it.
Myths
Siberian squill is a harmless, pet-safe little spring bulb.
Every part holds cardiac glycosides and rates as a high-severity poison. Eating it can bring on vomiting, diarrhea, and a lowered heart rate, and a real dose can be fatal. Keep the bulbs and plants away from pets and children.
Being a small ornamental bulb, it stays put where you plant it.
It naturalizes fast through self-seeding and bulb offshoots, slipping out of beds and into lawns and woodlands. It is considered invasive in parts of the US, so deadhead it and keep it away from wild ground.