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Plant care

Threadleaf Tickseed 'Moonbeam' (Moonbeam Coreopsis) care

Coreopsis verticillata

Also called Moonbeam Coreopsis, Whorled Tickseed, Thread-leaf Coreopsis.

RHS H6USDA 3-9Pet-safeIndoor 45-60 cm tall

Watering rhythm

7-10days

When the top 3-4 cm of soil is dry, roughly every 7-10 days; infrequent once established

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Light

Direct sun (at least 4-6 hours)

Soil

Well-draining, average to poor fertility loam or sandy soil

Humidity

35-55%

Temp

-20-35°C

Pet safety

Pet-safe

Mature size

45-60 cm tall

Care at a glance

Light

Most houseplants will scorch where threadleaf tickseed 'moonbeam' thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Requires full sun (minimum 6 hours daily) for the best flower production and most compact, upright growth habit. Partial shade reduces flowering significantly and causes the fine stems to lean or flop. Ideal for open, sunny borders and prairie-style plantings. 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 3-4 cm of soil is dry, roughly every 7-10 days; infrequent once established for threadleaf tickseed 'moonbeam', 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. Highly drought-tolerant and thrives in dry to average moisture soils. Overwatering and waterlogged soils cause root rot. Water deeply but infrequently to encourage deep rooting. Reduce watering in autumn as plants die back.

Soil and pot

Threadleaf Tickseed 'Moonbeam' grows best in well-draining, average to poor fertility loam or sandy soil. Thrives in lean, well-drained soils — rich, fertile soils promote excessive foliage at the expense of flowering. A neutral to slightly acidic pH of 6.0–7.0 is suitable. Avoid heavy clay unless amended generously with grit and organic matter. 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

Threadleaf Tickseed 'Moonbeam' sits happiest at around 35-55% humidity and -20-35°C (-4-95°F). Well-adapted to dry, low to moderate humidity conditions. Good air circulation helps prevent the occasional powdery mildew that affects Coreopsis in humid summers. Does not require humidity management. 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 threadleaf tickseed 'moonbeam' sparingly. Feed sparingly if at all — over-rich soil or heavy fertilising produces lush foliage and fewer flowers. A light balanced granular feed in spring in poor soils is the maximum required. Deadheading regularly is more effective than feeding for extending the bloom season. 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 threadleaf tickseed 'moonbeam' in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Powdery mildew — White coating on leaves during hot, humid summers; improve air circulation and maintain (but do not over-apply) soil moisture.
  • Floppy growth — Rich soils or too much shade cause stems to lean; grow in lean, well-drained soil in full sun.
  • Root rot — Consistently wet or waterlogged soils kill established plants; ensure free drainage.
  • Coreopsis spot (Septoria) — Small dark leaf spots appear during wet periods; remove affected foliage and improve air circulation.
  • Aster yellows — Phytoplasma disease causing distorted, yellowish growth; transmitted by leafhoppers — remove and destroy affected plants.

Companion plants

Threadleaf Tickseed 'Moonbeam' pairs well with Rudbeckia fulgida, Echinacea purpurea, Salvia nemorosa, and Hylotelephium 'Autumn Joy'. 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

Divide clumps every 2-3 years in spring to maintain vigour. The species also self-seeds freely; deadhead to prevent unwanted seedlings. Basal cuttings can be taken in spring and rooted in free-draining compost. 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

Threadleaf Tickseed 'Moonbeam' is pet-safe. Coreopsis verticillata is listed by the ASPCA as non-toxic to dogs, cats, and horses. 'Moonbeam' is a safe choice for gardens with 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.

Threadleaf Tickseed 'Moonbeam' care — frequently asked questions

What is the common name for Coreopsis verticillata?

Coreopsis verticillata is most commonly called Threadleaf Tickseed 'Moonbeam', but it is also known as Moonbeam Coreopsis, Whorled Tickseed, Thread-leaf Coreopsis. The names refer to the same species, so care instructions for Threadleaf Tickseed 'Moonbeam' apply identically to anything sold as Moonbeam Coreopsis.

How much light does threadleaf tickseed 'moonbeam' need?

Threadleaf Tickseed 'Moonbeam' grows best in direct sun (at least 4-6 hours). Requires full sun (minimum 6 hours daily) for the best flower production and most compact, upright growth habit. Partial shade reduces flowering significantly and causes the fine stems to lean or flop. Ideal for open, sunny borders and prairie-style plantings.

How often should I water threadleaf tickseed 'moonbeam'?

Water threadleaf tickseed 'moonbeam' when the top 3-4 cm of soil is dry, roughly every 7-10 days; infrequent once established. Highly drought-tolerant and thrives in dry to average moisture soils. Overwatering and waterlogged soils cause root rot. Water deeply but infrequently to encourage deep rooting. Reduce watering in autumn as plants die back. 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 threadleaf tickseed 'moonbeam' toxic to cats and dogs?

Threadleaf Tickseed 'Moonbeam' is pet-safe. Coreopsis verticillata is listed by the ASPCA as non-toxic to dogs, cats, and horses. 'Moonbeam' is a safe choice for gardens with pets.

What USDA hardiness zone does threadleaf tickseed 'moonbeam' grow in?

Threadleaf Tickseed 'Moonbeam' is rated for USDA zone 3-9 and RHS hardiness H6. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Threadleaf Tickseed 'Moonbeam' deep-dive guides

Every aspect of threadleaf tickseed 'moonbeam' care, each with its own calibrated guide:

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Related guides

Threadleaf Tickseed 'Moonbeam' is also known as Moonbeam Coreopsis, Whorled Tickseed, and Thread-leaf Coreopsis.