Bulb · Iridaceae
Spring Crocus
Crocus vernus
Plant the corms in fall and the spring crocus pushes up the first color of the year, often right through the snow.
Full sun
Every 7–14 days
USDA 3–8
2–6 in · 5–15 cm
Overview
The spring crocus is one of the earliest flowers to break a long winter, opening cups of purple, white, and lilac while the ground is still cold. It grows from a corm, a small swollen stem that stores everything the plant needs to bloom, and it returns on its own year after year. You'll find it scattered through lawns, edging beds, and pooled under trees where almost nothing else is awake yet.
It belongs to the iris family and stays low, just 2 to 6 inches (5 to 15 cm) tall, so it works best in drifts where the numbers carry the show. Each corm sends up grassy leaves with a pale stripe down the middle, then a short flush of flowers that lasts about three weeks before the plant fades back underground for summer. Left alone, a planting slowly spreads into a wider, fuller sweep.
This is the true spring crocus, and it is only mildly toxic to people and pets, a world apart from the deadly autumn crocus it is often confused with. It asks for little: a sunny, well-drained spot and a hands-off approach once the flowers are done.
Care
The short version: plant the corms in fall in a sunny, gritty, well-drained spot, give them medium moisture through bloom, then leave them dry and alone over summer and let the leaves yellow before you cut them back.
Light
Give crocuses full sun for the best and most plentiful flowers, though they take partial sun or light shade in stride. Spots under deciduous trees work well, since the corms get their sun in early spring before the leaves come out overhead.
Water
Through active growth and bloom they want medium, steady moisture, watered roughly every 7 to 14 days if rain is short. Once the foliage dies back, keep them on the dry side, because the corms are dormant in summer and rot in soggy ground.
Soil
Drainage is everything. Plant in gritty, sandy or loamy soil with some organic matter and a pH between 6.0 and 7.0, and stay away from heavy clay, which holds the water that kills corms.
Temperature
These are tough, cold-hardy plants that take winters down to -40°F (-40°C) and shrug off late frosts. They do their growing in cool weather and go dormant once summer heat arrives, handling daytime warmth up to about 75°F (24°C).
Humidity
Air moisture isn't something you need to manage. Ordinary outdoor humidity is fine, and what matters far more is keeping the soil from staying wet around the dormant corms.
Feeding
Work a low-nitrogen bulb fertilizer or bone meal into the soil at planting and that's mostly it. The corm already holds enough food to bloom once, so a light feed in fall and early spring is all the support it needs.
Pruning
There's no real pruning to do. Let the leaves stay and yellow on their own for about 6 weeks after the flowers fade, so the corm can recharge for next year, then clear the spent foliage away.
Repotting
In the ground, crocuses look after themselves for years. Divide a clump every 4 to 5 years when you notice fewer or smaller flowers, crowded corms, or a general drop in vigor.
Size & spacing
Plants stay small, reaching only 2 to 6 inches (5 to 15 cm) tall with a similar spread. Set the corms 3 to 6 inches (8 to 15 cm) apart so they have room to multiply into a fuller drift.
When to plant
Crocus timing runs backward from most flowers. You plant the corms in fall, several weeks before the ground freezes, and they spend winter rooting underground. Then they bloom in the first warm spell of spring, often by February, before fading away by early summer.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Plant corms in fall, about 3-4 inches deep and 3-6 inches apart, 6-8 weeks before the ground freezes.
- Harvest: Early spring (February to April), blooming for about three weeks.
Hardiness
USDA hardiness zones: 3–8
Temperature: down to -40°C
Troubleshooting
Crocuses are about as easy as a flower gets, and most of their problems trace back to soggy soil, hungry rodents, or crowding underground. Match what you're seeing below and the fix is usually simple. Catch each one early, before it spreads through the whole planting.
Soft, mushy corms that fail to come up
Wet feet are the usual killer. Corm rot sets in when heavy clay or a low, soggy spot keeps water sitting around the corm, and you'll know it by the soft, brown, foul tissue when you lift one. Pull and toss the rotted ones, then replant the healthy corms in gritty soil cut with sand or compost so water drains away fast.
Fix:
- Lift and discard rotted corms
- Replant healthy corms in gritty, well-drained soil
- Amend beds with sand or organic matter to improve drainage
Holes in the bed and corms vanishing after fall planting
Fresh-planted corms are a magnet for squirrels, chipmunks, mice, and voles, who dig them up and eat them before a single leaf appears. Lay hardware cloth or wire mesh over the bed until growth pushes through. Clearing away the papery husks helps too, since that scent is part of what draws them in.
Fix:
- Cover planting areas with hardware cloth or wire mesh until growth emerges
- Plant corms at the recommended depth and firm the soil
- Remove planting debris and papery corm husks that attract rodents
Fewer, smaller flowers in an old planting
When a clump has bloomed well for years and then thins out, it is usually just overcrowding as the corms multiply and compete underground. Cutting the leaves off too soon does the same damage, since the corm never finishes storing energy for next year. Dig and divide the clump after the foliage dies back, replant at proper spacing, and from now on let the leaves yellow on their own.
Fix:
- Dig and divide crowded clumps after foliage dies back
- Replant divided corms at proper spacing
- Allow foliage to remain about 6 weeks after bloom
Toxicity
Good news for households with pets and children: the spring crocus is only mildly toxic. Chewing the leaves or a corm may cause some drooling, vomiting, or diarrhea, but it isn't dangerous. The one thing to know is that it is a completely different plant from the autumn crocus (Colchicum), which is deadly, so make sure you know which one is in your garden.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that nibbles the leaves or a corm may drool, vomit, or get a bout of diarrhea. It passes on its own, and the spring crocus is nothing like its deadly autumn namesake.
Dogs Mild
Dogs that chew on the plant tend to drool and have an upset stomach for a short while. The trouble stays mild, though a big mouthful is worth a call to the vet.
Horses Mild
Grazing on the foliage can leave a horse with mild stomach upset and loose droppings. The reaction is minor, unlike the serious poisoning the autumn crocus causes.
Rabbits Mild
A rabbit that samples the leaves may get soft stools and a quiet, off-its-feed spell. Keep this plant out of the hutch and the run to be safe.
Livestock Mild
Cattle, goats, and sheep rarely bother with it, but a curious mouthful can bring on a little digestive upset that clears quickly.
Birds Caution
There's little specific data on pet birds, so treat it as a plant to keep out of reach rather than one proven safe.
People Caution
This is an ornamental, not a food. Eating the corm or leaves can bring on mild nausea and an upset stomach, so keep curious children from putting any part in their mouths.
Keep corms and plants away from pets that chew on plants; wash hands after handling.
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
Most garden crocuses are large-flowered Dutch types, and they're sold by color as much as by name. These are the ones you'll see most often.
Pickwick
Pale lilac petals are boldly striped with deep purple, giving each bloom a feathered, two-tone look.
Flower Record
Large, solid deep-purple flowers open wide and read as a strong block of color from across the yard.
Jeanne d'Arc
Pure white flowers spread well on their own, which makes this one a favorite for naturalizing in lawns and under trees.
Remembrance
Glossy, deep violet-purple flowers carry a slight sheen that catches the early spring light.
Striped Beauty
Light purple petals are striped with a darker purple, a softer take on the bicolor pattern than Pickwick.
How to propagate
DivisionEasy
After foliage dies back in late spring or early summer, replant in fall. · Replanted divisions establish over one season and bloom the following spring.
The simplest way to make more crocuses is to dig up a crowded clump every 4 to 5 years once the leaves have died back, pull the corms apart, and replant them with proper spacing that fall. They settle in over a single season and flower again the next spring.
Offsets & pupsEasy
Lift in summer dormancy; separate naturally formed cormels. · Small cormels may take 1-2 years to reach flowering size.
Each corm quietly produces small cormels around its base, and you can lift them during summer dormancy and twist them free. Grow these on for a year or two and they'll reach blooming size.
SeedModerate
Sow ripe seed in containers in late summer or fall. · Seed-grown plants take several years (often 3-4) to reach flowering size.
You can sow ripe seed in containers in late summer or fall, but it's a slow road, with plants taking 3 to 4 years to flower. Named cultivars won't come true this way, so save seed only if you're happy with a mix of seedlings.
Myths
All crocuses are the same plant, and equally dangerous or equally safe to pets.
These are two different plants that happen to share a common name. The spring crocus you plant for early color is only mildly toxic and causes minor stomach upset at most. The autumn crocus, Colchicum autumnale, belongs to a separate family and holds colchicine, which can cause bloody vomiting, organ damage, and bone marrow suppression in cats, dogs, and horses. Know which one you have before you judge the risk.
Crocuses need heavy feeding to bloom.
Each corm already carries enough stored food to flower once, so the first spring takes care of itself. A light, low-nitrogen feed worked in at planting is all you ever need, and piling on fertilizer does nothing for the flowers.