in bloom
now
through Sep
Bloom calendar
Mammoth Grey Stripe
Annual sunflower cultivar
At‑a‑glance
- Group/Class: Annual sunflower cultivar
- Height × spread: 8-12 ft × 2-3 ft (2.4-3.6 m × 0.6-0.9 m)
- Bloom window: mid summer to early fall
- Color & flower form: single large golden yellow ray florets with dark disk; 8-12 in heads (20-30 cm)
- Fragrance: 0 none
- USDA hardiness: grown as annual in all USDA zones
- Breeder / Year / Origin: unknown
- Cut‑flower notes: thick stems; best cut just as rays lift; typical vase life 6-12 days in clean water depending on cultivar and care
- Pet safety: safe
How it differs
- Taller than most garden sunflowers
- Usually single headed rather than freely branching
- Produces heavy edible seed heads
- Makes a seasonal screen rather than a bouquet crop
Strengths
- Impressive height and flower size
- Good seed production for wildlife and roasting
- Heat tolerant with adequate moisture
Care in one minute
Site: full sun with wind protection where possible
Soil: well‑drained soil with a slightly acidic pH of 6.0 to 6.8; loosen deeply for strong taproots
Water: deep, regular watering during dry spells
Feeding: avoid high nitrogen to limit floppy growth
Pruning: do not pinch single‑stem types
Overwintering: not applicable; warm‑season annual in North America
Watch‑outs
- Can lean or flop in wind without staking
- Birds and squirrels may damage maturing heads
- Needs ample space and sun
Best uses (tags)
Provenance note
An old grey‑striped seed form widely sold in North America; exact breeder and introduction date are not verified.
References
- USDA NRCS Plant Guide: Annual Sunflower
- Texas Master Gardeners: Sunflower ‘Mammoth’
- UMN Extension: Sunflowers
- ASPCA: Sunflower non‑toxic to pets
Similar Flowers
Enjoying our flower guides? Add YourFlowersGuide as a preferred source on Google — it helps more readers find us.
Add to Preferred Sources