Sunflowers are pretty big compared to most flowers, but there’s one behemoth relative of the sunflowers we all know and love.
The biggest sunflower out there is the Mongolian Giant sunflower and you won’t believe how big the seeds and blooms get!
Learn all about this variety, how to grow it, where to get high-quality seeds, and what makes it such a unique sunflower.
What is the Mongolian Giant Sunflower?
The Mongolian Giant sunflower is an heirloom variety and the largest species of sunflower.
They can reach heights of 14 feet, but it’s the blooms that are the most impressive. These sunflower heads can get as big as 18 inches across, with the characteristic bright and sunny yellow petals of their cousins.
Mongolian Giant sunflowers have a single giant bloom at the top with large green leaves all the way down. Think Jack and the Beanstalk, but with a gorgeous sunflower at the top!
The stalks of these flowers are extremely thick and woody to help support the height and weight of the bloom.
At the center of the bloom are tons of large, edible seeds, usually as long as an inch and a half. That makes these seeds the longest of any sunflower variety and the perfect snack when roasted!
Growing Mongolian Giant Sunflowers
Mongolian Giant sunflowers are so fun to grow, even if it’s just for the shock value of how huge they get. There are so many fun things you can do with them.
Because of their size, you can get strategic about where and how you grow them. They work perfectly as a border or along a fence, or even along a boring, plain garage or shed wall that could use a little color. They also make a great shade crop if you’re growing more heat-sensitive plants that don’t like full sun.
Have fun arranging them and planting a forest or play space for kids. Mongolian Giant sunflowers are so tall with such bushy leaves that little ones can let their imaginations run wild from within the foliage.
Grow them as a school project to teach students about gardening and flowers with a model that’s big enough to dig into and see all the details. Once the blooms are spent, cut the stalk at the bottom and repurpose it into a temporary fort or teepee.
These flowers are a great way to welcome pollinators to your yard, and you can also use them as a birdfeeder for your local feathered friends. Leave the blooms on the stalk or hang the heads upside down to let the birds feast on the seeds.
Grow Your Own
Set yourself up for success and see how big you can grow your Mongolian Giant sunflowers!
Wait until after the last frost in your area before you get going, and start by choosing the perfect spot. They love hot, sunny spaces and are drought and heat tolerant, so avoid areas with shade. The flowers will blossom from summer into fall.
When they get really tall, they’ll likely need some extra support to keep them upright. You can add stakes, or you can plant them strategically along fenceposts. Planting them along a wall or building also helps provide a wind block that could potentially knock them over.
Each sunflower will need plenty of room to get as big as possible, so make sure you choose a spot that can accommodate them. They do best with around 1 to 2 feet between each flower.
Mongolian Giant sunflower seeds can be direct sown or started in seed trays inside. Ideal soil temperatures are between 70 and 80 degrees F for seeds to germinate. It’s a good idea to fertilize your soil for adequate nutrients.
Gently press seeds about half an inch into the soil and cover lightly, being sure to keep the soil moist. They should sprout in 5 to 12 days.
Once your sunflowers start to reach toward the sky, water them regularly with a garden hose or irrigation. Adding mulch can help the roots maintain moisture.
As they get taller, your Mongolian Giant sunflowers may be at risk of toppling either from wind or the weight of the flower head. Add stakes as needed or tie them to posts with gardening twine if you’ve planted them along a fence.
Take advantage of trap crops like onions and squash to draw pests away from your Mongolian Giant sunflowers. Deer may also be interested in them before they really get big, so be on the lookout for nibbled leaves and add some kind of physical barrier so they can’t munch the top of the plant right off.
Your sunflower should reach maturity in about 90 days from planting. If you want to bring any of the flowers inside, harvest them before the blooms open up so you can enjoy them for as long as possible. You’ll need a very sharp knife or large shears to get through the thick stalk.
Collect the seeds after the blooms are spent. Like all sunflowers, they are annual and will need to be replanted each year so you can save some for next season. And of course, roast the rest up for a healthy and delicious snack!
Where to Find Mongolian Giant Sunflowers
Your best bet for finding Mongolian Giant sunflowers is to grow them yourself. Head to Hoss Tools for reliable, high-quality seeds.
Finding fresh flowers is a bit more challenging. Their size makes them impractical for most places to sell as cut flowers, and they don’t exactly fit neatly into a bouquet. You won’t find this variety at the grocery store.
If you aren’t able to grow them yourself but still want to admire them or get your hands on seeds for snacking, check with farmers in your community. Since they can be used as shade crops and edible seeds can be harvested, there may be someone in your area who grows them.
Mongolian Giant Sunflowers Are Larger Than Life
You really can’t believe the size of Mongolian Giant sunflowers until you see them in person.
The blooms are as beautiful as they are huge, and there are a bunch of fun things you can do with them. Despite their size, they’re easy to grow almost anywhere.
Sunflowers come in many unique varieties, so head to our Sunflower Page to see them all!