Growing crocus is easy and rewarding. These fascinating flowers require minimal care, grow back stronger year after year, and present some of springtime’s earliest, loveliest blooms.
Are you interested in brightening up your lawn, watching flowers emerge from snow, or harvesting your own saffron spice? Then it’s time to get acquainted with crocuses. In the sections below, we’ll cover everything you need to know to get started planting and caring for these unique perennials.
Characteristics of Crocus
The Crocus genus consists of around 100 species of flowering plants in the Iridaceae (iris) family. These low-growing perennials produce dainty cup-shaped flowers in shades of purple, blue, yellow, and white.
They’re often referred to as bulb flowers, but crocuses grow from corms, not bulbs. While bulbs have scales, a corm is a single piece of tissue. However, this distinction isn’t important for growing purposes.
Crocuses grow almost like wildflowers, requiring minimal care and coming back stronger each year. You can plant them in flower beds, pots, or even scattered throughout a grass lawn.
In cold regions, crocuses are known for poking up through the snow in late winter. The emergence of color on a bed of white creates a beautiful winter aesthetic and signals the changing of the season.
Crocuses are also famous for producing saffron, the world’s most expensive spice. Saffron comes from the stigmas of just one crocus species, Crocus sativus.
Planting Crocus: When, Where, and How
When to Plant Crocus
Most crocuses are spring-blooming. The best time to plant spring-flowering crocus corms is usually September or October, around seven weeks prior to the first expected frost. This provides the corm with sufficient time spent in dormancy. Extended exposure to cold temperatures is a necessary part of the growth process that leads to spring flowering.
Some varieties, including saffron crocus, are autumn-blooming. These should be planted in August or September. Fall bloomers mature quickly, flowering 6–10 weeks after planting.
Always make sure you know which type of crocus you have, and note that crocus corms don’t store well and should be planted quickly.
Where to Plant Crocus
Crocus grows well in USDA Plant Hardiness Zones 3–8, everywhere but the very hottest regions. Crocuses will grow in partial sun but thrive in full sun (six or more hours of direct sunlight per day).
How to Plant Crocus
Plant crocus corms in nutrient-rich well-draining soil. Plant at depths of 3–6 inches (7–15 cm). Make sure the pointy end of the corm is facing up. The individual plants will only grow to heights of around six inches (15 cm) and don’t take up much space, so they can be planted close together. Just leave around three inches (7 cm) of space between corms.
You can also plant crocuses in pots, indoors or outdoors. When growing corms or bulbs in containers, you can plant more shallowly and closer together. Keep the pot in a cool, dark place for winter dormancy. During this time, water the corm but allow the soil to dry thoroughly between waterings. Then, move the pot to a sunny location in late winter when it’s time for the plant to bloom.
When planting crocuses in a grass yard, spread them out. The lawn looks more attractive if the flowers are scattered, rather than concentrated in a few areas. To plant bulbs in grass, gently remove a patch of grass, dig the planting hole, and insert the corm. Pat the grass back into place, then water the area generously.
Caring for Crocuses
Crocuses planted in the ground require minimal care. During the growing season (spring or fall), water crocuses thoroughly once or twice per week. In summer and winter, only water once per month if there hasn’t been any precipitation. Indoor potted crocuses should be watered sparingly, allowing the soil to dry out completely between waterings.
Crocuses don’t require pruning or deadheading. However, if a flower bed is filling up with crocuses after several years of growth, it’s helpful to remove the old, dying plants. This prevents overcrowding and reduces the chance of pests or disease spreading. Note that a crocus plant can live for up to five years.
For crocus growing in a grass lawn, it’s best to wait to mow until the flowers have died back. Mowing over the spent flowers in spring won’t kill the bulbs or prevent them from growing back next year.
Crocuses and Pests
Crocuses aren’t especially vulnerable to insect pests. However, squirrels and other rodents are fond of digging up the bulbs.
Protecting bulbs against rodents is notoriously tricky. If you grow an abundance of crocuses, you may simply choose to let the squirrels enjoy their share. If you choose to fight back, the most effective method is to plant bulbs inside protective material. This may involve burying a number of bulbs inside a wire cage or between layers of hardware cloth.
Types of Crocuses
Among the 100 or so crocus species, the most important distinction is between spring-blooming and fall-blooming. Most crocuses are spring-blooming. However, one of the most famous species—Crocus sativus (Saffron Crocus)—is fall-blooming.
Whether they bloom in spring or fall, all crocuses tend to be deer and rabbit resistant, slow spreaders that are great for naturalizing, and they’re generally carefree if provided with a sunny to partly sunny location with well-draining soil. All crocuses go dormant after their flowering period.
Popular spring-blooming crocus species include:
Snow Crocus (Crocus sieberi)
Snow crocuses produce a showy combination of blue petals blending to white with brilliant yellow centers. Plants grow 3-4” (7-10 cm) tall with fragrant flowers. USDA Hardiness zone 4-8. Blooms March-April. One of the earliest crocuses, hence the common name “snow crocus”. It’s not unusual to see this species emerging through the snow cover in early spring.
Dutch Crocus (Crocus vernus)
Basic colors are purple or white, but many colorful Dutch crocus cultivars have been developed. Plants grow 3-6” (7-15 cm) tall with blooms in April. Native to the Alpine regions of Europe. USDA Hardiness zone 3-8. Also known as large flowering crocus, spring crocus, or giant crocus. Can be planted around black walnut trees.
Silvery Crocus (Crocus biflorus)
Silvery crocus is a petit crocus species with interesting petal combinations of violet-blue and white. Plants grow 2.5-3” (6-7 cm) tall with flowers in March. Native to Mediterranean regions, especially Italy and Turkey. USDA Hardiness zone 4-7. Also known as Scotch crocus, although this plant is not native to that region of the world.
Popular fall-blooming crocus species are:
Bieberstein’s Crocus (Crocus speciosus)
Bieberstein’s crocus is a very common, easy-to-grow heirloom crocus originating in regions along the Black Sea but transported throughout the world in the 1800’s. Plant grows to 3-5” (7-12 cm) with violet-blue flowers appearing in September and October. USDA Hardiness Zone 4-8.
Autumn Crocus (Colchicum autumnale)
This plant is commonly referred to as a crocus, but the autumn crocus actually belongs to a separate plant genus. Prefers partial shade and does well naturalized along wooded areas. Plants are 6-10” (15-25 cm) tall with lavender-pink blooms in September and October. USDA Hardiness Zone 4-9.
Saffron Crocus (Crocus sativus)
The dried stamens of the saffron crocus are the source of saffron spice and can also be used for making a deep yellow dye. Plants are 4-6” (10-15 cm) tall and produce lavender-purple flowers in October. If you’re interested in harvesting saffron from your flowers, remember that only the saffron crocus produces this substance. Other crocuses don’t produce edible parts. USDA Hardiness Zone 5-8.
Planning a Bulb Garden that Blooms Throughout the Spring
Bulb (and corm) flowers like crocuses and tulips are beautiful, easy to plant and have high success rates. Many are hearty perennials that come back stronger year after year.
With proper timing, your bulb garden can bloom throughout the spring. Find tips and plant suggestions for season-long blooms in our guide to planning a long blooming bulb garden.
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