- Variety Info
- Sowing Info
- Growing Info
- Learn More
Variety Info
Family: Asteraceae
Type: Sunflower (Learn more)
Native: North America
Hardiness: Annual
Exposure: Full sun
Bloom Period: Summer to frost
Plant Dimensions: 6'–12' tall
Variety Info: Up to 12"-wide flowers with yellow petals and a brown center. Single type.
Attributes: Attracts Pollinators, Cut Flower, Drought Tolerant, Heat Tolerant, Edible Flower
Sowing Info
When to Sow Outside: RECOMMENDED. 1 to 2 weeks after your average last frost date.
When to Start Inside: 2 to 4 weeks before your average last frost date. Sunflowers are senstive to root disturbance; sow in biodegradable pots that can be planted directly in the ground.
Days to Emerge: 10–15 days
Seed Depth: ¼"–½"
Seed Spacing: A group of 3 seeds every 24"
Thinning: When 3" tall, thin to 1 every 24"
Your hardiness zone is
Growing Info
Harvesting: Seeds are ready to harvest when the back of the head has dried and turned brown, about 4 weeks after the flowers have been pollinated. Petals will have wilted and fallen off, and the seeds will be plump, and colored white with gray/black stripes. Seeds ripen around the outside of the flower first; the ones in the center will ripen last. Average yield is approximately 1 pound per head.
- Chandi C.Verified BuyerRated 5 out of 5 stars12/21/25Great Seeds
Wow. I did an experiment to see if I could grow these in good soil and in awful soil and these little seeds took to both. I have one flower that is about 5 feet tall and many more still growing. So fun and easy.
Which best describes you as a gardener? BeginnerBIBotanical Interests12/22/25Hey Chandi,
Thank you so much for taking the time to share your awesome experiment with our Mammoth Sunflower seeds! We're absolutely thrilled to hear that these tough little seeds performed so well in both good and awful soil - that's exactly the kind of resilience we love to see! A 5-foot tall sunflower with many more still growing sounds incredible! We love that you found them so fun and easy to grow. Thank you for choosing us and for sharing your growing success with us. Keep on growing 🌻️
- Ryan 🌱Verified BuyerRated 5 out of 5 stars12/20/25Impressive and fun 🌻
Every seed I've planted has sprouted. Outdoors, just miracle grow, easy. The bigger the pot the bigger the flower! They make tons of roots and they're thirsty. They bring so much joy every day 🌻
Which best describes you as a gardener? BeginnerBIBotanical Interests12/22/25Hey Ryan,
Thank you so much for taking the time to share your amazing experience with our Mammoth Sunflowers! We're absolutely thrilled to hear that every single seed sprouted for you - that's incredible! Your tip about the bigger pot leading to bigger flowers is spot on, and we love that you discovered how thirsty these beauties can get with all those roots. There's nothing better than hearing that our sunflowers are bringing you joy every single day! Thank you for choosing us and for sharing your growing success with us. Keep on growing 🌻️
- Juanita L.Verified ReviewerRated 5 out of 5 stars10/29/25Second generation in my high desert garden
I harvested and saved the Mammoth seed heads last summer 2024 and some seeds of course found their way to garden beds. Growing on the edges of beds this spring they were a welcome shade from the hot dry desert climate. 2025 volunteer sunflowers were even bigger, with great seeds harvested.
Which best describes you as a gardener? IntermediateBIBotanical Interests10/31/25Hey Juanita,
Thank you so much for this fantastic 5-star review! "Second generation in my high desert garden" with those volunteer sunflowers that were "even bigger, with great seeds harvested" is exactly what we love to hear about Mammoth Sunflower Seeds - and we absolutely love that your saved seed heads naturally created an even more impressive next generation!
Wow, there's something so satisfying about those self-seeding success stories where nature takes over and rewards you with volunteer plants that actually outperform the original planting! There's nothing quite like discovering that your Mammoth Sunflowers not only thrived in that challenging high desert climate but also provided welcome shade while producing seeds that grew into even more spectacular plants the following year!
It's so wonderful that they found their way to the edges of your beds and became such helpful shade providers during those hot, dry conditions - Mammoth Sunflowers really are such generous plants that keep giving back season after season with their impressive size, practical benefits, and abundant seed production! Your multi-generational growing success and desert climate triumph will be so inspiring for other gardeners who want to discover just how adaptable and self-sustaining Mammoth Sunflower Seeds can be for creating those lasting, productive displays that just keep getting better!
Keep on growing 🌻️
- Mackenzie S.Verified BuyerRated 5 out of 5 stars1/25/255 Stars
Christmas gift for a friend.
He and his girlfriend love it.
- Allen R.Verified BuyerRated 5 out of 5 stars11/23/245 Stars
Amazing seeds throughout the couple years of growing with all kinds of plants from your business. Thank you to all your employees. Gardening keeps me from hurting people.