in bloom
now
through Oct
Bloom calendar
Purity
single‑flowered selection; annual cosmos
At‑a‑glance
- Group/Class: single‑flowered selection; annual cosmos
- Height × spread: 36 to 48 in (90 to 120 cm) × 20 to 40 in (50 to 100 cm)
- Bloom window: summer to frost
- Color & flower form: pure white single daisies; about 3 in heads
- Fragrance: 0 none
- USDA hardiness: grown as annual in all zones; frost tender
- Breeder / Year / Origin: unknown
- Cut‑flower notes: cut when the first petals just open; stems are flexible but serviceable; typical vase life 4 to 7 days with preservative.
- Pet safety: safe; generally non‑toxic to pets; ingestion may cause mild stomach upset.
How it differs
- Single white blooms instead of mixed colors.
- Tall habit with longer cutting stems than dwarf types.
- Light texture from finely divided foliage.
- Dependable bloom through the warm season with deadheading.
Strengths
- Combines easily in bouquets and borders.
- Flowers attract bees and other pollinators.
- Performs in average soils if drainage is good.
- Useful for continuous cutting from summer to frost.
Care in one minute
Provide full sun and well‑drained soil of low to moderate fertility.
Water to establish then water when the top inch is dry.
Pinch once to encourage branching; stake if exposed; deadhead consistently.
Direct sow after frost or transplant hardened‑off starts.
Allow some seed heads to mature if self‑seeding is welcome.
Watch‑outs
- Tall stems can lean in wind and rain without support.
- Grey mold can occur in wet periods.
- Aphids may colonize tender growth.
- Excess fertilization can reduce flowering.
Best uses (tags)
Provenance note
RHS documents Cosmos bipinnatus ‘Purity’ as a tall, pure white selection; breeder and year are not listed.
References
- Royal Horticultural Society – Cosmos bipinnatus ‘Purity’
- NC State Extension – Cosmos overview
- University of Illinois Extension – Cosmos care
- Royal Horticultural Society – Cosmos advice page
