Skyscraper Sunflower (Mongolian Giant)

Mongolian Giant Sunflower is a magnificent, towering heirloom known for its impressive height and enormous golden blooms. These giants can soar 12–14 feet tall, creating a stunning natural backdrop, while their dramatic flower heads often span 14–18 inches across, glowing with vibrant yellow petals and a bold chocolate center. Gardeners adore this variety for its ability to transform any outdoor space into a cheerful summer spectacle, attract pollinators from near and far, and produce an abundance of large, nutritious seeds perfect for snacking or feeding backyard wildlife. Growing your own Mongolian Giants adds a sense of accomplishment as you watch each sturdy stalk rise day by day, and they make a fun, interactive project for kids and adults alike. Their impressive size makes them an eye-catching choice for borders and fences, and they remain surprisingly easy to grow—even for beginners—thriving in most sunny locations with minimal care. Add these towering beauties to your garden for a showstopper that brings joy, color, and life all season long.

Also Known As: Mongolian Sunflower, Russian Sunflower, Titan Sunflower, Mammoth Sunflower, Mongol Giant Sunflower, Skyscraper Sunflower, Siberian Giant Sunflower, Mongolia Sunflower Seeds, Giant Heritage Sunflower, Heirloom Mongolian Giant Sunflower.

Plant Name:	Sunflower, Mongolian Giant
Latin Name:	Helianthus annuus
Days to Germinate:	7-14
Days to Bloom:	100-120
Plant Height:	10 - 14 Feet
Spread:	2 - 3 Feet
Bloom Diameter:	14 - 18 Inches
Growth Habit:	Upright
USDA Zones:	2-11
Lifespan:	Annual
Brand:	TomorrowSeeds
Sunlight:	Full Sun, Partial Shade
Pollination:	Heirloom, Open-Pollinated
GMO:	No
Fungicide-Treated Seeds*:	No
Seeds Packed For**:	2026

*Fungicide-treated seeds protect the seedlings from diseases until they are up and growing. Do not eat treated seeds.
**Seeds are freshly packed for the growing season of the year listed. Seeds are still viable beyond pack date. Store in a cool and dry location such as the refrigerator or basement to best preserve germination rates.

Planting Instructions:

Soil Preparation:

Choose an area with heavy, well-draining soil that receives at least 6 hours of sunlight each day. Remove weeds, large rocks, and litter from the planting area. Leave small weeds and dead grass, they will enrich the soil when turned under. Spade or till the soil 6-8 inches deep. Loosening the soil will help the plant establish strong roots. If the soil is heavy or clay-like, mix in some sand or compost to improve drainage. Optionally, form rows of soil beds 4-6 inches high and at least 2-3 feet apart. This formation of ridges will help with drainage, ensure good airflow, and make harvesting for cut flowers easier. Lay down 1/2"-3/4" peat moss, sawdust, or potting soil, the soil surface. This layer is beneficial for flower seeds because it can the improve the germination environment and prevent soil crusting.

Planting:

Starting Indoors: For earlier Sunflower blooms, you may optionally start planting indoors in containers 4-6 weeks before the last expected frost date in Spring, keeping seedlings at least 65F. Harden off then transplant seedlings outdoors in a sunny location when temperatures are consistently above 60F. To transplant seedlings, prepare a transplant hole outdoors in a sunny location. Remove the plants carefully from the pots or flats and set them in the transplant holes, burying some of the stem in the ground. Pack the soil loosely around the plant and leave a slightly sunken area around each plant to hold water. Water the plants after transplanting.

Directly Sowing: If directly sowing outdoors, plant after all danger of frost has passed in spring and soil temperatures reach at least 60F. Fall planting is not recommended unless planting outdoors in environments with mild, frost-free winters for a head start in the following spring, or planting indoors with supplemental grow lights.

To plant, make holes 1-2 inches deep and spaced 18-24 inches apart down the rows of raised beds.In small plots, flower seeds may be scattered then covered with soil. Once seedlings emerge, plants can separated and spaced 18-24 inches apart to allow room for mature plants to spread and prevent overcrowding. Water after planting.

Planting Depth:	1-2 inches
Within-Row Spacing:	18-24 inches
Between-Row Spacing:	2-3 feet

Care During the Season:

Sunflowers are relatively drought-tolerant once established and require minimal care but thrive with full sun for at least 6-8 hours daily and regular watering, especially during dry spells. Water deeply at the base of sunflower plants. Fertilization is usually unnecessary if the soil is already nutrient-rich, but for poor soil, a balanced fertilizer at planting and once again midway through the growing season can help promote healthy growth. While sunflowers are hardy, larger plants may need staking to prevent them from falling over in windy conditions. To harvest, once the sunflowers bloom and the flower heads mature, leave the seeds to ripen fully while still attached to the plant. Harvest the flower heads when the petals start to dry and the seeds appear plump and firm, cutting the head with a portion of the stem. Properly dried flower heads can be stored for seed saving or enjoyed as beautiful dried arrangements.