Join the RHS today and support our charitable work
Keep track of your plants with reminders & care tips – all to help you grow successfully
For the latest on RHS Shows in 2021, read more
RHS members get reduced ticket prices
RHS members get free access to RHS Gardens
Free entry to RHS members at selected times »
Reduced prices on RHS Garden courses and workshops
020 3176 5800
Mon – Fri | 9am – 5pm
Help us achieve our goals
Join the RHS today and support our charity
We have combined these two powerful search tools into a single Find a Plant service searching over 250,000 plant records.
Virtually all of the features of the old searches are still available and in addition we have added several new features to create a more comprehensive and user friendly search experience.
When using this search
Search by plant name, key attributes or both to find plant details and a list of
AGM plants have been through a rigorous trial and assessment programme. They are:
This plant will provide nectar and pollen for bees and the many other types of pollinating insects.
It is included in an evolving list of plants carefully researched and chosen by RHS experts. Divided into 3 groups these lists, linked below, are maintained by a team of RHS staff and are reviewed annually.
Other common names
cosmea Mexican aster
purple Mexican aster Spanish needles
Cosmos can be annuals or perennials with simple or pinnately divided leaves and large, long-stalked daisy-like flowers in summer
C. bipinnatus is a tall, bushy annual to 2.5m, with very finely divided, mid-green leaves, and large flowers to 8cm across, usually white or pink the wide outer rays surround a central disc of tightly clustered, usually yellow, inner disc florets. Flowering late summer and into autumn, until frost occurs. Many named cultivars and selections are available, including doubles, forms with tubular rays, and picotee colours
Mexico, S US
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
Aspect West-facing or South-facing
Exposure Exposed or Sheltered
MoistureMoist but well-drained
SoilChalk, Loam, Sand
pHAcid, Alkaline, Neutral
Time to ultimate height
Grow in moderately fertile, moist, but well-drained soil in full sun. Deadhead flowers to prologue flowering season. Leave a few seedheads to ripen to selfseed if required
Propagate by seed at 16°C in mid-spring under glass, or in situ in late spring
Suggested planting locations and garden types
Cottage & Informal Garden Wildflower meadow City & Courtyard Gardens Patio & Container Plants Prairie Planting Wildlife Gardens
Pruning none required
Pests Aphids and slugs may be troublesome
Susceptible to grey moulds
RHS members can get exclusive individual advice from the RHS Gardening Advice team.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.