Common Crocus (Crocus)

Common Crocus, also frequently called Dutch crocus or spring crocus, and botanically known as Crocus vernus, are delightful, low-growing perennials that herald the arrival of spring with their vibrant cup-shaped flowers. These charming blooms, available in a spectrum of colors including purple, yellow, white, and striped varieties, are a welcome sight after a long winter, offering a burst of beauty and a vital early source of nectar for pollinators.

At Gardencenterpoint.com, we believe that every gardener, from novice to expert, can experience the joy of growing these early spring beauties. This guide is designed to provide you with all the information you need for success, from choosing the right bulbs to providing the best planting and aftercare, ensuring you are rewarded with many years of delightful spring flowers. We will explore how to grow and care for this beautiful plant.

What is a Common Crocus? Understanding the Basics

The common crocus, Crocus vernus, is a member of the Iridaceae family, which also includes irises and gladioli. These plants are native to the Alps, the Pyrenees, and the Balkans, and they have naturalized in many other parts of the world, including North America. They are cormous perennials, meaning they grow from corms, which are underground storage structures similar to bulbs.

Common crocuses are hardy in USDA zones 3-8. They are adaptable to the soil. Good drainage is a must. In the best conditions, Crocuses will multiply, forming beautiful carpets of color year after year. Here are some key characteristics of Common Crocus:

Common name	Common Crocus, Dutch Crocus, Spring Crocus
Botanical name	Crocus vernus
Family	Iridaceae
Genus	Crocus
Species	vernus
Origin	Alps, Pyrenees, Balkans
Native	Europe
Life cycle	Perennial
Plant type	Corm
Hardiness zone	3, 4, 5, 6, 7, 8
Sunlight	Full Sun, Partial Shade
Maintenance	Low
Water	Medium
Drainage	Well-Drained
Spacing	3-4 inches
Flowering period	Late Winter, Early Spring
Height	3-6 inches
Growth rate	Moderate
Flower color	Purple, White, Yellow, Striped Variations
Stem color	Green
Flower benefit	Early Bloom, Attracts Pollinators
Garden style	Rock Garden, Border, Naturalized Areas, Lawns
Uses	Ornamental, Container, Mass Planting, Ground Cover
Soil pH	Neutral, Slightly Alkaline (6.0 to 7.5)
Soil Type	Sandy, Loamy, Well-drained
Toxicity	Mildly toxic to pets if ingested in large quantities.
Deer Resistance	Generally resistant.
Pest & Disease Resistance	Generally resistant, but can be susceptible to corm rot in poorly drained soils.

Unlike true bulbs (like tulips or daffodils), which have layers, corms are solid masses of stem tissue. Each year, the corm produces new roots and a flowering stem. After flowering, the original corm shrivels, and one or more new corms form on top of the old one. These new corms will produce flowers the following spring.

Common crocuses are relatively small plants, typically reaching only 3-6 inches (7.5 – 15 cm) in height. Their flowers are cup-shaped and come in a variety of colors, including shades of purple, lavender, yellow, white, and bi-colored varieties. The flowers typically appear in early spring, often before the last frost, and they close at night and on cloudy days.

The leaves of the common crocus are narrow and grass-like, with a white stripe down the center. They emerge from the ground at the same time as, or shortly after, the flowers. The foliage is important for photosynthesis, providing the energy needed for the corm to grow and produce flowers the following year. After the plant has flowered and the foliage begins to yellow, it is essential to allow the leaves to die back naturally. This allows the corm to store energy for the next growing season.

Types and Varieties of Common Crocus

While “Common Crocus” generally refers to Crocus vernus, there are numerous cultivars and hybrids within this species, offering a wide range of colors and patterns. Here are some popular varieties:

• ‘Pickwick’: A striking variety with large, lilac-striped flowers. The white base color is beautifully veined with purple.
• ‘Remembrance’: A classic deep purple crocus with a glossy sheen. It’s known for its vigorous growth and abundant blooms.
• ‘Jeanne d’Arc’: A pure white variety that creates a stunning contrast in the garden. Its large flowers open wide in the sun.
• ‘Yellow Mammoth’: Also known as ‘Golden Yellow,’ this variety boasts large, bright yellow flowers that are a cheerful sight in early spring.
• ‘Vanguard’: An early-blooming variety with silvery-lavender flowers. It often opens a week or two before other Crocus vernus cultivars.
• ‘Flower Record’: This variety is known for violet-blue petals.
• ‘Grand Maitre’: Offers large, lavender-blue flowers.

This is just a small selection, and there are many other beautiful Crocus vernus cultivars available. When choosing varieties, consider your color preferences, bloom time (some bloom earlier than others), and the overall effect you want to create in your garden. Gardencenterpoint.com recommends checking with local nurseries for varieties that thrive in your specific climate.

It is also worth noting that there are other species of crocus that are commonly grown, though they are not technically “common crocus” (Crocus vernus). These include:

• Crocus chrysanthus (Snow Crocus): These are smaller than Crocus vernus and bloom even earlier, often appearing while snow is still on the ground. They come in a variety of colors, including yellow, white, blue, and purple. Popular cultivars include ‘Snowbunting’ (white), ‘Blue Pearl’ (light blue), and ‘Cream Beauty’ (creamy yellow).
• Crocus tommasinianus (Tommies): These are very vigorous and naturalize readily. They have slender, lavender-purple flowers and are known for their squirrel resistance. ‘Ruby Giant’ is a popular, deeply colored cultivar.
• Crocus sieberi: Another early bloomer with vibrant colors. ‘Tricolor’ is a particularly striking cultivar with purple, white, and yellow bands.

The diverse range of crocus species and cultivars allows gardeners to create a prolonged display of color, starting in late winter and continuing through early spring. By planting a mix of varieties, you can enjoy these cheerful blooms for several weeks.

Planting Common Crocus

Planting common crocus corms is a relatively simple process, but timing and technique are key to success. Fall is the ideal planting time, allowing the corms to establish roots before winter.

Step 1: Choose the Right Time

• Plant crocus corms in the fall, about 6-8 weeks before the ground freezes. This typically means September to November in most regions, but adjust based on your local climate. A good rule of thumb is to plant when the average nighttime temperatures are consistently below 60°F (15°C).

Step 2: Select a Suitable Location

• Sunlight: Common crocuses thrive in full sun (at least 6 hours of direct sunlight per day) but will also tolerate partial shade (4-6 hours of sunlight). In warmer climates, some afternoon shade can be beneficial.
• Soil: Well-drained soil is crucial. Crocuses will rot in soggy soil. If your soil is heavy clay, amend it with compost, peat moss, or other organic matter to improve drainage. A slightly acidic to neutral soil pH (6.0-7.0) is ideal.
• Location: Consider planting crocuses in areas where they will be visible in early spring, such as along walkways, in rock gardens, at the front of borders, or under deciduous trees (which will leaf out after the crocuses have finished blooming). They also look beautiful naturalized in lawns.

Step 3: Prepare the Soil

• Loosen the soil to a depth of about 6-8 inches (15-20 cm).
• Remove any weeds, rocks, or debris.
• Amend the soil with compost or other organic matter if needed to improve drainage and fertility.

Step 4: Plant the Corms

• Dig holes 3-4 inches (7.5-10 cm) deep and 2-3 inches (5-7.5 cm) apart.
• Place the corms in the holes with the pointed end facing up.
• Cover the corms with soil and gently firm the soil around them.
• Water thoroughly after planting.

Step 5: Mulch (Optional)

• Applying a thin layer of mulch (1-2 inches/2.5-5 cm) such as shredded bark, wood chips, or pine needles can help to conserve moisture, suppress weeds, and moderate soil temperature. However, avoid piling mulch directly on top of the corms, as this can promote rot.

Planting in Lawns:

If you’re planting crocuses in a lawn, you can use a special bulb planter or a sharp trowel to create holes. Lift a small section of turf, place the corm in the hole, and replace the turf. Water well to help the turf re-establish.

Planting in Containers:

Crocuses can also be grown in containers. Use a well-draining potting mix and choose a pot with drainage holes. Plant the corms at the same depth and spacing as you would in the ground. Water thoroughly after planting. Container-grown crocuses may need to be brought indoors or protected during severe winter weather in colder climates.

Caring for Common Crocus

Once planted, common crocuses require minimal care. However, providing the right conditions will ensure healthy growth and abundant blooms.

Light:

As mentioned earlier, common crocuses prefer full sun (at least 6 hours of direct sunlight per day) but will tolerate partial shade (4-6 hours of sunlight). In warmer climates (zones 7-8), some afternoon shade can help to protect the flowers from excessive heat.

Water:

• During the growing season (spring): Water regularly, especially during dry spells. The soil should be kept moist but not waterlogged. Aim for about 1 inch (2.5 cm) of water per week, either from rainfall or irrigation.
• After flowering: Reduce watering as the foliage begins to yellow.
• During dormancy (summer): Crocuses prefer dry conditions during their summer dormancy. Avoid overwatering, as this can cause the corms to rot.
• During the Fall: Water well after planting.

Soil:

Well-drained soil is the most critical factor for crocus health. They thrive in moderately fertile, sandy loam soil with a slightly acidic to neutral pH (6.0-7.0).

• Improving Drainage: If you have heavy clay soil, amend it with plenty of organic matter, such as compost, peat moss, or aged manure. This will improve drainage and aeration. You can also consider planting crocuses in raised beds or containers.
• Soil Testing: A soil test can provide valuable information about your soil’s pH and nutrient levels. Your local extension service can provide information on soil testing.

Fertilizer:

Common crocuses generally don’t require a lot of fertilizer.

• At Planting Time: You can incorporate a small amount of bone meal or a balanced, slow-release bulb fertilizer into the planting hole.
• After Flowering: Once the flowers have faded, you can apply a top dressing of a balanced fertilizer or compost to help replenish nutrients in the soil. Avoid high-nitrogen fertilizers, as these can promote excessive foliage growth at the expense of flowers. A fertilizer formulated for bulbs is a good choice.

Additional Care Tips:

• Deadheading: Removing spent flowers (deadheading) is not necessary for crocuses, but it can improve the appearance of the planting. Simply snip off the faded flower heads with scissors or your fingers. Do not remove the foliage until it has turned yellow and withered naturally.
• Protecting from Pests: More information in section 5.
• Dividing Corms: More information in section 6.

Common Crocus Problems: Pests, Diseases, and Solutions

Common crocuses are generally quite trouble-free, but they can occasionally be affected by pests and diseases.

Pests:

• Squirrels and Rodents: These animals are the most common pests of crocus corms. They may dig up and eat the corms, especially soon after planting.
  • Solutions:
    • Plant the corms deeper (4-5 inches/10-12.5 cm).
    • Cover the planting area with wire mesh or hardware cloth until the corms have sprouted.
    • Use repellents (such as those containing capsaicin).
    • Interplant crocuses with daffodils, which rodents tend to avoid.
    • Provide an alternative food source (such as corn or sunflower seeds) away from the crocus planting area.
• Mice and Voles: These rodents may tunnel underground and eat the corms.
  • Solutions:
    • Similar to those for squirrels.
    • Use traps.
    • Improve soil drainage to make the area less attractive to voles.
• Bulb Mites: Tiny pests that can infest corms, causing stunted growth and distorted flowers.
  • Solutions:
    • Discard infested bulbs.
    • Before planting, treat corms with a miticide if bulb mites are a known issue in your area.

Diseases:

• Corm Rot: This is usually caused by poorly drained soil and overwatering. The corms become soft and mushy, and the plant may fail to emerge or collapse.
  • Solutions:
    • Ensure excellent soil drainage.
    • Avoid overwatering.
    • Discard any infected corms.
    • Do not replant crocuses in the same area if corm rot has been a problem.
• Botrytis Blight (Gray Mold): This fungal disease can cause gray, fuzzy mold on the leaves and flowers, especially in damp, cool conditions.
  • Solutions:
    • Provide good air circulation.
    • Avoid overhead watering.
    • Remove any infected plant parts.
    • Fungicides can be used as a preventative measure in areas where Botrytis is a common problem.
• Viral Diseases: Several viruses can affect crocuses, causing symptoms such as stunted growth, mottled leaves, and distorted flowers. There is no cure for viral diseases.
  • Solutions:
    • Remove and destroy any infected plants.
    • Control aphids, which can spread viruses.
    • Purchase certified virus-free corms from reputable suppliers.

Other Problems:

• Failure to Bloom: This can be caused by several factors, including:
  • Corms planted too shallowly: Plant at the recommended depth (3-4 inches/7.5-10 cm).
  • Overcrowding: Divide corms every few years (see section 6).
  • Insufficient sunlight: Ensure the plants receive adequate sunlight.
  • Poor soil fertility: Fertilize as needed (see section 4).
  • Damage from pests or diseases: Address any pest or disease problems promptly.
  • Immature Corms: Newly planted corms may take a year to establish before they bloom.

Propagating Common Crocus

Common crocuses naturally multiply by producing new corms (called cormels or offsets) each year. Over time, a single corm can develop into a large clump. Dividing these clumps is an easy way to propagate crocuses and expand your spring display.

When to Divide:

• The best time to divide crocuses is in the summer, after the foliage has turned yellow and withered completely. This is when the corms are dormant.

How to Divide:

1. Carefully Dig Up the Clumps: Use a garden fork or spade to gently lift the entire clump of corms from the ground. Be careful not to damage the corms.
2. Separate the Corms: Gently pull apart the clump, separating the individual corms and cormels. You may need to use a sharp knife to cut through any connecting tissue.
3. Discard Damaged or Diseased Corms: Inspect the corms carefully and discard any that are soft, mushy, or show signs of disease.
4. Replant Immediately or Store: You can replant the corms immediately in a new location, following the planting instructions in section 3. Alternatively, you can store the corms for planting in the fall.
5. Curing and storage. If storing, allow corms to dry in a cool, dry, well-ventilated area for a few days. Then, place them in a mesh bag or a paper bag with dry peat moss or vermiculite. Store in a cool, dark, dry place (ideally around 40-50°F/4-10°C) until planting time.

Note: Smaller cormels may not bloom in the first year after division. It may take a year or two for them to reach flowering size.

Landscaping with Common Crocus

Common crocuses are versatile plants that can be used in a variety of landscape settings. Their early bloom time and vibrant colors make them a valuable addition to any spring garden.

Design Ideas:

• Naturalizing in Lawns: This is one of the most popular ways to use crocuses. Scatter the corms randomly over the lawn and plant them where they fall for a natural-looking effect. The crocuses will bloom before the grass needs to be mowed.
• Rock Gardens: Crocuses are well-suited to rock gardens, where their small size and bright colors can be appreciated up close. Plant them in pockets of well-drained soil between rocks.
• Borders: Use crocuses at the front of flower borders to create a colorful edge. They can be planted in drifts or in combination with other early spring bulbs.
• Containers: Crocuses can be grown in containers on patios, decks, or balconies. They can be combined with other spring-blooming plants, such as pansies or violas.
• Under Deciduous Trees and Shrubs: Plant crocuses under trees and shrubs that will leaf out after the crocuses have finished blooming. This provides a beautiful early spring display before the trees and shrubs provide shade.
• Woodland Gardens: Crocuses can be naturalized in woodland gardens, where they will spread and create a carpet of color.

Companion Plants

Crocuses pair well with many other early spring-blooming plants. Here are some good companion plant choices:

• Snowdrops (Galanthus): These delicate white flowers bloom even earlier than crocuses and provide a beautiful contrast.
• Winter Aconite (Eranthis hyemalis): These bright yellow flowers bloom around the same time as crocuses.
• Glory-of-the-Snow (Chionodoxa): These star-shaped flowers come in shades of blue, pink, and white.
• Reticulated Iris (Iris reticulata): These miniature irises bloom in early spring and come in a variety of colors.
• Early Tulips (Tulipa): Some early-blooming tulip varieties, such as Tulipa kaufmanniana and Tulipa greigii, bloom at the same time as crocuses.
• Early Daffodils (Narcissus): Similar to tulips, choosing early blooming varieties will provide a longer blooming period.
• Hellebores (Helleborus): These shade-loving perennials bloom in late winter and early spring and provide a beautiful backdrop for crocuses.
• Pansies and Violas: These cool-season annuals provide continuous color throughout the spring and can be planted alongside crocuses.

When choosing companion plants, consider their bloom time, height, color, and growing requirements to create a harmonious and visually appealing display.

Common Crocus FAQs

Q: Are crocuses deer-resistant?

A: Crocuses are generally considered deer-resistant, although hungry deer may occasionally nibble on them. If deer are a significant problem in your area, consider planting them in a protected location or using repellents.

Q: Are crocuses poisonous to pets?

A: Common Crocus (Crocus vernus) is generally considered non-toxic to humans but can be mildly toxic to pets if ingested in large quantities. Symptoms of poisoning may include vomiting, diarrhea, and drooling. If you suspect your pet has ingested crocus corms, contact your veterinarian. It’s always best to supervise pets and children around plants.

Q: How long do crocus flowers last?

A: Individual crocus flowers typically last for 1-2 weeks, depending on the weather. The overall bloom period for a planting of crocuses can last for several weeks, especially if you plant a mix of varieties with different bloom times.

Q: Do I need to dig up crocus corms every year?

A: No, you do not need to dig up crocus corms every year. They are hardy perennials that can be left in the ground year-round in USDA zones 3-8. However, you may want to divide them every few years to prevent overcrowding (see section 6).

Q: Can I force crocuses to bloom indoors?

A: Yes, crocuses can be forced to bloom indoors, providing a touch of spring color during the winter months. The process involves chilling the corms for a period of time to mimic winter conditions.

Q: What is the difference between a crocus and a colchicum?

A: Crocus and colchicum (also known as autumn crocus) are often confused because they look similar and both bloom from corms. However, they are different plants belonging to different families. Here are some key differences:

Feature	Crocus (Crocus)	Colchicum (Colchicum)
Family	Iridaceae	Colchicaceae
Bloom Time	Spring (mostly), some fall-blooming species	Fall
Leaves	Narrow, grass-like, with a white stripe down the center	Broad, strap-like, appear in spring, die back in summer
Stamens	3	6
Toxicity	Generally non-toxic to humans, mildly toxic to pets in quantity	Highly toxic to humans and pets; all parts of the plant are poisonous

Colchicum is highly toxic, and ingestion can be fatal. It’s important to be able to distinguish between these two plants.