In many regions, crocus flowers (Crocus spp.) mark the arrival of spring. These early bloomers can often be seen peeking up through the snow well before any other flowers appear on the landscape. They grow in a range of conditions, including woodlands, coastal gardens, and suburban lawns. Crocuses are low-growing, clump-forming perennial plants from the iris (Iridaceae) family. Bloom colors on the tube-shaped flowers include mauve, lavender, and yellow. There are more than 80 crocus species, but most of the bulbs available are hybrids.
|Botanical Name||Crocus spp.|
|Mature Size||6 inches tall, 1- to 3-inch spread|
|Sun Exposure||Full sun to part sun|
|Soil Type||Most soil types, well-draining|
|Flower Color||Purple, blue, yellow, orange, pink, white|
|Hardiness Zones||3 to 8|
|Native Area||Europe, North Africa, Asia|
How to Grow Crocuses
Crocuses are most often planted for early spring color, though there are also varieties that bloom in late fall and early winter. Spring-blooming crocuses should be planted in the early fall. Plant them around 4 inches deep and 2 to 4 inches apart with the pointed end up. Sometimes it can be difficult to tell which is the pointed end. If you can't, don't worry about it too much; the plant will grow toward the light. Adding some bulb food or bone meal to the soil will ensure the plants have all the nutrients they need to get started.
To extend the bloom time, mix different species of crocuses in your garden. In addition, planting them where other plants will fill in and hide their foliage will help to prolong blooming and give the crocuses a chance to store energy for the next season. Crocuses fade quickly once the weather gets hot.
Crocuses do best in full sun. But because they bloom so early in the year when there is little foliage on the trees, spots that are shady in the summer are usually fine for spring-blooming crocuses.
Crocus plants prefer a neutral soil pH of 6 or 7, and they're usually not fussy about the soil type. But a well-draining soil is crucial. As with most bulb-like plants, crocuses do not like to sit in soggy soil, which can cause them to rot.
Crocuses are generally low-maintenance plants. They like to be watered regularly in the spring and fall. If there is no snow cover, the bulbs will also need water throughout the winter. However, they go dormant in the summer and prefer drier soil during this time.
Temperature and Humidity
Crocus bulb hardiness varies slightly depending on which type you are growing, but most crocuses are reliable within USDA hardiness zones 3 to 8. They bloom and survive best where winters are cold. Crocus bulbs need a 12- to 15-week period of cold temperatures of around 35 to 45 degrees Fahrenheit to set their blooms. Humidity usually isn't an issue, though excessive humidity can lead to rot.
Crocuses do not require a lot of fertilizer. They store their own energy in their bulbs, which is why it is essential that you do not cut back the leaves until they begin to turn yellow. However, a light top dressing of bulb food or bone meal in the fall is a good idea if you have poor soil.
It is not necessary to divide your crocus plants. In many areas, crocuses are somewhat short-lived, and you might need to replant every few years. However, if your crocuses do very well and start to multiply, they will eventually begin to bloom less as the clumps become dense. If that happens, you can dig up and divide the bulbs when the foliage starts to die back. Replant the bulbs at least 3 inches apart or in another location entirely.
Common Pests and Diseases
Crocuses are susceptible to viruses, which can cause distortions, streaking, and buds that fail to open. There is no cure for viral diseases; if they strike, dispose of the plants to prevent spreading the virus.
But the biggest problem is bulbs and flowers being eaten by chipmunks, deer, rabbits, and squirrels. Other animals, such as skunks, dig the bulbs out of the ground while searching for insects. There are liquid deterrents that can be sprayed on the leaves and granular deterrents you can scatter to prevent nibbling. You can also buy wire cages to protect the bulbs when you plant them. If you find your plants are constantly being harmed, avoid using bone meal, which can attract animals. Instead, try interplanting your crocuses with daffodils, which animals hate.
Varieties of Crocuses
There are many beautiful varieties of crocuses to grow, including:
- Bieberstein's crocus (Crocus speciosus): This species blooms in the fall, featuring lilac blue flowers with dark veining.
- 'Bowles White' crocus (Crocus atticus 'Bowles White'): This variety produces snowy white flowers with yellow throats and blooms in the early spring.
- Dutch crocus (Crocus vernus 'Pickwick'): The flowers of this variety are striped in pale and dark lilac, blooming in the spring.
- 'Purpureus Grandiflorus' crocus (Crocus vernus 'Purpureus Grandiflorus'): This variety blooms in the spring with abundant violet flowers.
- Tricolor crocus (Crocus sieberi 'Tricolor'): This plant blooms in late winter to early spring and features bands of lilac, white, and yellow on its petals.