Largeflower Tickseed
Coreopsis grandifloraUSDA | Grow Zone
3-9Outdoors all year in zones 3 to 9. Anywhere colder, keep it as a houseplant. Protect it below 40°F.
- Light
- Full sun, 6-8 hours
- Water
- When top 1 in is dry
- Humidity
- 40-60%
- Temperature
- 65-75°F (18-24°C)
- Difficulty
- Beginner
- Growth
- Moderate
- Mature size
- 2-3 ft tall, 1-2 ft wide
- Pets
- Non-toxic to pets and children
Coreopsis grandiflora, commonly known as Largeflower Tickseed, is a vibrant perennial that brings cheerful blooms to gardens. Native to North America, it is cherished for its bright yellow flowers and ability to attract pollinators, making it a popular choice for gardeners looking to enhance their landscape.
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Ideal temperature
65-75°F is where it grows fastest. Below 40°F cold damage starts.
Spacing and harvest
- Mature size
- 2-3 ft tall, 1-2 ft wide
- Plant apart
- 12-24 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Coreopsis grandiflora prefers well-drained soil and should be watered deeply but infrequently.
Water once the top inch of soil feels dry, typically every 1-2 weeks during the growing season. In hotter months, you may need to increase frequency. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and browning leaf edges.
Light
This plant thrives in full sun, requiring at least 6-8 hours of direct sunlight daily.
Ideal placement includes south or west-facing gardens. It can tolerate partial shade but may produce fewer flowers and become leggy in low light conditions.
Soil
Coreopsis grandiflora prefers sandy or loamy soil with a pH range of 6.0 to 7.0.
Good drainage is essential to prevent root rot. A recommended potting mix includes a blend of potting soil, sand, and perlite to enhance drainage.
Humidity
This plant enjoys average humidity levels of 40-60%.
To increase humidity, mist the leaves or place a humidity tray filled with water nearby. Signs of humidity stress include browning leaf tips and wilting.
Temperature
Coreopsis grandiflora thrives in temperatures between 65-75°F (18-24°C) and is hardy in zones 3-9.
It can tolerate brief periods of heat but may struggle in extreme cold, so provide mulch in winter to protect roots.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10, applying every 4-6 weeks during the growing season.
Reduce feeding in late summer and fall. Signs of nutrient deficiency include stunted growth and pale leaves.
Pruning
Prune Coreopsis grandiflora in early spring to remove dead or damaged stems.
Deadheading spent flowers encourages more blooms and prevents self-seeding. Use sharp, clean scissors or pruning shears for best results.
Repotting
Repot every 2-3 years or when the plant becomes root-bound, indicated by roots growing out of the drainage holes.
Choose a pot 1-2 inches larger in diameter. Carefully remove the plant, loosen the roots, and place it in fresh potting mix.
Propagation
Propagation can be achieved through seeds or division.
For seeds, sow them in spring after the last frost, covering lightly with soil. For division, carefully dig up established plants in spring or fall and separate the root clumps, replanting immediately.
When it's unhappy
Yellow leaves
Why it happens
Often caused by over-watering or poor drainage.
How to fix it
Ensure the soil drains well and reduce watering frequency.
Root rot
Why it happens
Excess moisture in the soil.
How to fix it
Improve drainage and avoid watering until the soil dries out.
Leggy growth
Why it happens
Insufficient light exposure.
How to fix it
Move the plant to a sunnier location to encourage bushier growth.
Pests (aphids, spider mites)
Why it happens
Common pests that can infest the plant.
How to fix it
Treat with insecticidal soap or neem oil, and ensure good air circulation.
Fungal diseases (powdery mildew)
Why it happens
High humidity and poor air circulation.
How to fix it
Ensure proper spacing between plants and apply fungicide if necessary.
Care through the year
Spring
In spring, prune back any dead stems and fertilize with a balanced fertilizer to encourage new growth. This is also the best time to propagate by division.
Summer
During summer, ensure consistent watering, especially in hot weather. Deadhead spent flowers regularly to promote continuous blooming.
Fall
In fall, reduce watering as the plant prepares for dormancy. Cut back spent foliage and apply mulch to protect roots during winter.
Winter
In winter, avoid over-watering. If in a pot, move it to a sheltered location to protect from frost, and ensure it is not exposed to extreme cold.
Toxicity & Safety
Coreopsis grandiflora is non-toxic to pets and children, making it a safe choice for gardens. No known toxic parts or symptoms of ingestion.
Good to know
How often should I water my Coreopsis grandiflora?
Water your Coreopsis grandiflora when the top inch of soil feels dry, typically every 1-2 weeks during the growing season.
Why are my Coreopsis grandiflora leaves turning yellow?
Yellow leaves can indicate over-watering or poor drainage. Check the soil moisture and ensure it drains well.
What type of soil is best for Coreopsis grandiflora?
This plant prefers sandy or loamy soil with a pH of 6.0 to 7.0 and good drainage to prevent root rot.
How can I propagate Coreopsis grandiflora?
You can propagate Coreopsis grandiflora by seeds or division. Sow seeds in spring or divide established plants in spring or fall.
What pests should I watch for on Coreopsis grandiflora?
Common pests include aphids and spider mites. Regularly inspect your plant and treat with insecticidal soap if necessary.
When should I prune my Coreopsis grandiflora?
Prune in early spring to remove dead stems and deadhead spent flowers throughout the blooming season to encourage more blooms.
Is Coreopsis grandiflora safe for pets?
Yes, Coreopsis grandiflora is non-toxic to both pets and children, making it a safe addition to your garden.
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