Coreopsis grandiflora Seeds | Large-flowered Coreopsis
LATIN NAME: Coreopsis grandiflora
COMMON NAME: Large-flowered Coreopsis
Plant Profile
Coreopsis grandiflora is a North American perennial of the Asteraceae, found from Quebec and Ontario south through the eastern states and west into Oklahoma and Arkansas. It grows in prairie, open woodland and along roadsides, in poor, stony ground that dries out in summer.
It makes a clump of lance-shaped leaves 40 to 60 cm high, with flower stems that rise above the foliage and carry golden daisies 5 to 6 cm across, often with a toothed or lobed ray and a darker orange centre. The flowers are produced from early summer until autumn if the plants are deadheaded, and a well-grown clump can carry fifty stems at once.
The common name tickseed refers to the seed, which is a small dark achene that resembles a tick, and the genus name comes from the Greek for bug-like, for the same reason. It ranks among the few garden perennials whose name describes its seed rather than its flower.
Science & Biotechnology
Coreopsis is a genus of about 80 species, all North American except for a few in South America and Africa, and it sits in the Coreopsideae, the same tribe as Cosmos and Bidens. The genus has been split and rejoined several times, and some species have been moved to Bidens on molecular evidence.
The yellow colour is a mixture of carotenoids and aurones, and the darker orange centre is produced by a higher concentration of the same pigments. The ray florets are sterile in some species and female in others, and the breeding of the garden forms has concentrated on doubling the ray and on producing a second flush after the first is cut back.
The F1 hybrid Early Sunrise, raised in the 1980s, was a significant step because it flowers in the first year from seed, which most perennials do not. That trait comes from a day-neutral selection and has been built into most of the modern seed strains, so a packet sown in spring gives flowers by July.
The cultivar Sunray, with fully double flowers, has been grown since the 1950s and is still the most widely sold seed strain in Europe, while Early Sunrise remains the standard for growers who want flowers in the first year. Both are selections of this species rather than hybrids, so they come reasonably true from seed. Fellow Asteraceae members here: Coreopsis basalis, Coreopsis lanceolata and Dimorphotheca sinuata.
Uses & Benefits
This is a plant for the middle of a border, a prairie planting or a wildflower meadow, where its long season and its tolerance of poor ground make it valuable. It combines well with ornamental grasses, with blue flowers such as Nepeta and Salvia, and with the tall daisies of late summer.
It ranks among the best perennials for cut flowers, since the stems are long, stiff and straight, and the flowers last a week in water. A row of it in a cutting garden will supply golden daisies from June to September for very little work.
It is also widely cultivated in China, where it has naturalised in several provinces, and it is used in municipal plantings for its drought tolerance and its long flowering season. The plant is not edible, and it has no medicinal use in Western practice, though some Coreopsis species were used by Native American groups for dyes and for medicine.
Growing from Seed
Sow under glass six to eight weeks before the last frost, at 18 to 21 °C, and dust the seed over with a little mix. The first seedlings appear in about fifteen days. The seed is large and germinates reliably, and the seedlings grow quickly.
Move them into 7 cm pots and hold them at 15 °C. Plant out after the last frost, 30 to 40 cm apart, in full sun. The plant tolerates poor, dry soil and needs no feeding; rich soil produces soft growth that flops and flowers less.
Deadhead regularly to keep the flowers coming, and cut the whole plant back by a third in midsummer if it becomes leggy, which forces a second flush in autumn. Divide clumps every three years in spring, discarding the woody centre. In a wet winter the crown can rot, so plant it in a raised bed or on a slope if your soil is heavy.
Our Take
Coreopsis is one of the most reliable perennials for a hot, dry border, and one of the cheapest to raise from seed. It flowers for four months, it takes poor soil, and it asks for nothing except sun and the occasional deadheading.
Grow it in the middle of a border, in a row for cutting, or in a meadow mix. Cut it back in midsummer for a second flush, and divide it every few years. It is not a plant that will surprise you, but it will not let you down.
Related Reading
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