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Plant care

Coreopsis 'Sunray' (Sunray Tickseed) care

Coreopsis grandiflora 'Sunray'

Also called Sunray Tickseed, Bigflower Coreopsis 'Sunray', Large-flowered Coreopsis.

RHS H5USDA 4-9Pet-safeIndoor 45-60 cm tall

Watering rhythm

7-10days

When the top 3-5 cm of soil is dry, roughly every 7-10 days

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Light

Direct sun (at least 4-6 hours)

Soil

Average to lean, well-drained soil

Humidity

35-65%

Temp

-10-32°C

Pet safety

Pet-safe

Mature size

45-60 cm tall

Care at a glance

Light

Most houseplants will scorch where coreopsis 'sunray' thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Requires full sun (6-8 hours minimum) to flower at its best. Insufficient light results in weak, leggy stems and poor flowering. An ideal border front or container plant in a sunny position. A plant moved abruptly from low light to direct sun bleaches in 48 hours — always acclimatise over a week.

Watering

Aim for when the top 3-5 cm of soil is dry, roughly every 7-10 days for coreopsis 'sunray', but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Moderate water needs once established. Water consistently during dry spells, especially in the first season. Avoid wet, waterlogged conditions, which cause root rot.

Soil and pot

Coreopsis 'Sunray' grows best in average to lean, well-drained soil. Performs well in average or even poor soils with good drainage. Rich soils promote lush foliage at the expense of flowers and make stems more prone to flopping. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Coreopsis 'Sunray' sits happiest at around 35-65% humidity and -10-32°C (14-90°F). Tolerates a range of humidity levels. Good airflow helps prevent foliar diseases. Avoid very humid, airless positions. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed coreopsis 'sunray' sparingly. Minimal fertiliser is needed. A single application of balanced slow-release granules in spring is sufficient. Over-fertilising causes flopping and reduces bloom number. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on coreopsis 'sunray' in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Short-lived perennial die-back — C. grandiflora can behave as a short-lived perennial in colder climates. Deadhead consistently and divide every 2-3 years to prolong the plant's life.
  • Stem rot in wet soils — Excess soil moisture, especially in winter, is the main cause of plant loss. Improve drainage or grow in raised beds.
  • Leafhoppers / aster yellows — Leafhoppers transmit aster yellows phytoplasma, causing distorted growth. Remove affected plants immediately.
  • Powdery mildew — Can occur in warm, humid spells. Improve airflow and avoid wetting foliage; treat with potassium bicarbonate if severe.
  • Slugs — Young basal growth is vulnerable in spring. Use physical barriers or organic slug control around emerging shoots.

Companion plants

Coreopsis 'Sunray' pairs well with Achillea millefolium, Gaillardia 'Burgundy', Rudbeckia hirta, and Verbena bonariensis. These are species with similar light and water needs, so you can group them in the same room or on the same shelf and water as a batch.

Propagation

Easily grown from seed sown under cover in late winter; germination is rapid. Clumps can also be divided in spring. Deadhead regularly to extend the flowering season. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Coreopsis 'Sunray' is pet-safe. Coreopsis species are listed as non-toxic to dogs and cats by the ASPCA. 'Sunray' is a cultivar of Coreopsis grandiflora and is considered safe for pets. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Coreopsis 'Sunray' care — frequently asked questions

What is the common name for Coreopsis grandiflora 'Sunray'?

Coreopsis grandiflora 'Sunray' is most commonly called Coreopsis 'Sunray', but it is also known as Sunray Tickseed, Bigflower Coreopsis 'Sunray', Large-flowered Coreopsis. The names refer to the same species, so care instructions for Coreopsis 'Sunray' apply identically to anything sold as Sunray Tickseed.

How much light does coreopsis 'sunray' need?

Coreopsis 'Sunray' grows best in direct sun (at least 4-6 hours). Requires full sun (6-8 hours minimum) to flower at its best. Insufficient light results in weak, leggy stems and poor flowering. An ideal border front or container plant in a sunny position.

How often should I water coreopsis 'sunray'?

Water coreopsis 'sunray' when the top 3-5 cm of soil is dry, roughly every 7-10 days. Moderate water needs once established. Water consistently during dry spells, especially in the first season. Avoid wet, waterlogged conditions, which cause root rot. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is coreopsis 'sunray' toxic to cats and dogs?

Coreopsis 'Sunray' is pet-safe. Coreopsis species are listed as non-toxic to dogs and cats by the ASPCA. 'Sunray' is a cultivar of Coreopsis grandiflora and is considered safe for pets.

What USDA hardiness zone does coreopsis 'sunray' grow in?

Coreopsis 'Sunray' is rated for USDA zone 4-9 and RHS hardiness H5. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Coreopsis 'Sunray' deep-dive guides

Every aspect of coreopsis 'sunray' care, each with its own calibrated guide:

Featured in these plant shortlists

Coreopsis 'Sunray' qualifies for 8 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

  • Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
  • Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
  • Best pet-safe flowering plants — Flowering houseplants the ASPCA lists as non-toxic to cats and dogs — colour and blooms in a pet home, without the worry.
  • Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
  • Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
  • Best houseplants for a cool room — Houseplants that tolerate cool conditions down to about 10°C — for an unheated spare room, hallway, porch or a home kept cool.
  • Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
  • Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
  • Browse all 30 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Coreopsis 'Sunray' is also known as Sunray Tickseed, Bigflower Coreopsis 'Sunray', and Large-flowered Coreopsis.