Large Flower Tickseed (Coreopsis grandiflora)

Common Coreopsis, Large Flower Tickseed, Largeflower Tickseed, Tickseed

Large-flowered tickseed (Coreopsis grandiflora) is a flowering plant that blooms from late spring to early fall. The Latin name Coreopsis grandiflora means “bug view” and “large flower.” The common name refers to the small black seeds produced by the plant.

I. Appearance and Characteristics 

Coreopsis grandiflora is a North American species of perennial plant in the family Asteraceae. The common name is large-flowered tickseed. It is found in eastern Canada (Quebec, Ontario, New Brunswick) and much of the United States, especially the south-central part of the country (Oklahoma, Arkansas, etc.). The species is widely cultivated in China and naturalized there.

The Latin specific epithet grandiflora means large-flowered. The plant attracts bees and butterflies.

In the UK the cultivar ‘Early Sunrise’ has received the Royal Horticultural Society’s Award of Garden Merit.

The large-flowered tickseed typically reaches a height of 1 to 3 feet and can spread about 1 to 2 feet wide. It has a moderate growth rate, averaging a few inches per month during the growing season. The roots are fibrous and do not typically cause problems with invasiveness or damage to structures. The stems are erect, slender, and ribbed, often branching in the upper part of the plant. They are green to reddish in color and can be either glabrous or pubescent.

The leaves of Coreopsis grandiflora are simple, lanceolate to oblong in shape, and arranged oppositely along the stem. They can be up to 3 inches long, with entire margins and a slightly leathery texture. Botanically, the leaves are sessile or short-petiolate and can exhibit a glabrous or sparsely pubescent surface.

The flowers of Coreopsis grandiflora are its most distinguishing feature. They are bright yellow with a toothed, lobed appearance, typically 1.5 to 2.5 inches in diameter. The bloom period extends from early summer to early fall, with peak flowering in midsummer. The flowers are borne on long peduncles and are composed of a central disc of tubular florets surrounded by a fringe of ray florets.

The fruit of Coreopsis grandiflora is a small, dry achene that is equipped with a pappus of scales, aiding in wind dispersal.

II. How to Grow and Care

Sunlight

Large-flowered tickseed requires sufficient sunlight and prefers direct sunlight, so it is good for sunny gardens or balconies. To grow indoors, at least 6 hours of sunlight is needed. For maximum blooming, over 12 hours of sunlight is best.

Large-flowered tickseed can survive in partially-shaded environments. However, excessive shade can result in decreased photosynthetic rate, slow growth rate, produce thin, weak stems, difficulty in branching, and fewer flowers. Your plant will be healthier in a bright place.

Temperature 

Large-flowered tickseed grows on grasslands or plains with a very dry environment. It likes a warm and dry growing environment, though it tolerates occasional wet weather. It grows best between 10 to 30 ℃. Cold temperatures result in slow growth. Sufficient water is required during germination, but adult plants have no special requirement for humidity.

Watering

Keep the soil slightly moist but without accumulated water until it grows into an adult plant. After that, large-flowered tickseed will be very drought-tolerant. It can be watered once a week, which helps grow new roots. Keep the soil moist to a depth of 2.5 cm when checked with fingers. Excessive water causes spindling.

It is best to water large-flowered tickseed in the morning so the leaves are kept dry during the day. This prevents sunburn and bacteria growth. Use rainwater or distilled water rather than tap water. Tap water contains a lot of calcium, magnesium, and other mineral salts, and long-term use tends to cause soil compaction and poor air permeability, causing poor growth.

Soil

Large-flowered tickseed adapts to most soil; some varieties even tolerate dry and rocky soil. However, it prefers moist, loose, permeable, well-drained sandy loam, with a pH value of 5.5-6.5. Add a permeable and loose medium, such as sphagnum moss and coco coir, to garden soil and organic matter to increase water retention. An example of a culture medium formula is 1/2 coco coir + 1/4 garden soil + 1/4 vermiculite or river sand. NPK fertilizer and organic fertilizer should be added in spring.

Fertilizing

There is basically no need for fertilizer. In fact, excessive fertilizer inhibits blooming. If the soil is good, just add some NPK fertilizer or organic fertilizer in spring.

Planting Instructions

Plant large-flowered tickseed in spring or fall; in subsequent years, rely on natural seeding. Its natural seeding range is 30 to 61 cm, and its lifespan is three to five years. When it starts to bloom less, its life is ending, and it should be replaced with new plants. Sow indoors 4-6 weeks before the last frost. The germination temperature should be 16 to 25℃.

During germination, the medium should be kept moist and the air humidity should be kept at 90%-95%, and then gradually reduced after germination. Germination takes four to six days. When two or three true leaves grow out, transplant to a garden or pot. After transplanting, water thoroughly to keep the root system and soil in close contact. The whole seedling period takes 4-5 weeks, and 13-15 weeks are needed from sowing to blooming.

Pruning

Cutting back the top of a declining perennial to the ground or near ground level will promote vigorous new growth, rejuvenating the plant. To encourage continuous blooming, you can cut back during the growing season, staggering sections of your coreopsis flower patch weekly.

Deadheading or removing the wilted bloom and stem can keep the plant blooming throughout summer and fall. The plant will not form new flower buds on a stem that holds a faded flower.

Propagation

Sowing or division propagation can be performed at home. The germination rate of seeds is above 50%, and seeds can germinate in 4-6 days. Many tender branches on its creeping stem can also be used for cuttage in summer.

Transplanting 

For the best success with large-flowered tickseed, transplant it during the ideal season of early-to-mid spring when temperatures are mild. Choose a location with well-draining soil and adequate sun exposure. Gently handle the roots during transplanting to ensure its growth and establishment.

Pests and Diseases

Large-flowered tickseed is relatively pest-free but can occasionally be affected by aphids (Aphidoidea) and leafhoppers (Cicadellidae). These insects can be managed with insecticidal soap or neem oil. The plant may also experience issues with powdery mildew or root rot in overly moist conditions. Ensuring proper drainage and air circulation can help prevent these problems.

Potting and Repotting 

Coreopsis grandiflora can be grown in containers. If you start them in seedling containers, you can size them up and transplant them into larger ones. Coreopsis need containers at least 8 to 10 inches deep and wide with ample drainage holes. This plant’s roots do not tolerate soggy, standing water.

After several years, if the plant’s roots appear to grow out of drainage holes, it’s time to divide the plant, as noted in the section about propagation. Once divided, replant the divided part in its container and backfill the rest with fresh soil.

Place the container in a spot with at least six to eight hours of full sun. In the hot summer months, give more water than if it’s in the ground. Containers heat up, and water evaporates from potting soil much sooner than in-ground plants.

Overwintering

Coreopsis grandiflora are hardy plants. You don’t have to give these plants winter protection, but if you have the perennial variety that returns annually, you can keep the roots healthy by ensuring the plant receives regular water up until the first frost. Cut back the stems down to the ground. Insulate the roots by layering 2 to 3 inches of mulch at the soil surface. Remove the mulch after the threat of frost is over.

III. Uses and Benefits 

Large-flowered tickseed is often found in informal or cottage gardens. Its large flowers and ease of growing work particularly well when plantd in large, dramatic drifts. This self-seeding plant is a good flower for beds and borders. Cranesbill and lavender make great companion plants because of their contrasting coloring.

IV. Harvesting and Storage

Generally speaking, large-flowered tickseed can bloom twice a year, once in spring or summer and once in fall. Its flowers can be appreciated for a long time. If it is not harvested, it can bloom for as long as one or two months. After harvest, the vase life of a single flower is between three and seven days. Use sharp gardening scissors to cut at the base of the stem, and prune the base of the stem obliquely at 45° to increase the water absorption area. Put it in a vase with clean water.

Large Flower Tickseed (Coreopsis grandiflora) Details

Common name Common Coreopsis, Large Flower Tickseed, Largeflower Tickseed, Tickseed
Botanical name Coreopsis grandiflora
Plant type Herbaceous Perennial
Hardiness zone 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Medium
Harvest time Summer
Height 1 ft. 0 in. - 3 ft. 0 in.
Width 1 ft. 0 in. - 3 ft. 0 in.
Sunlight Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil condition Clay
Flower color Gold/Yellow
Leaf color Green