Sunflowers are such a joy to grow and watch in the garden. They can reach such a towering height, and their cheerful yellow blooms always seem to light up a space. If you’re looking for an easy annual to add some drama to your garden, tall sunflower varieties should definitely be at the top of your list!
Tall sunflowers typically reach a height of 12 to 16 feet tall but can grow taller in optimal growing conditions. Popular tall sunflower varieties to grow include Mammoth Sunflower, Mongolian Giant Sunflower, Skyscraper Sunflower, and American Giant Sunflower. Some types require staking, especially in windy areas. The tallest sunflower on record reached an incredible height of 30 feet tall!
Read on to learn all about tall sunflowers and how to grow them.
Tall sunflower varieties
Growing the tallest sunflower plants starts with choosing a variety that has tall genetics. For extra-tall plants, you’ll need seeds that want to grow tall and then growing conditions that allow them to. Here are some popular tall sunflower varieties:
1. Mammoth sunflower
The Mammoth Sunflower, also called the Mammoth Grey Stripe Sunflower, is perhaps the most popular tall sunflower variety. This heirloom variety is known for its tall stalk, giant flower head, and high-quality sunflower seeds.
Mammoth Sunflowers grow to reach about 12 feet tall. Each plant grows one flower that spans 8″-12″ wide. These plants take about 75 days (2.5 months) to reach maturity after planting.
2. Mongolian Giant sunflower
The Mongolian Giant Sunflower is a classic tall sunflower variety that produces a single giant sunflower head. These sunflowers are easy to grow (and they grow fast!). The flowers attract beneficial pollinators and the seeds are excellent for eating fresh or roasted.
Mongolian Giant Sunflowers grow to reach about 14 feet tall. The flower head on each plant is usually around 16″ wide! This variety takes about 90 days (3 months) from planting to maturity.
3. Skyscraper sunflower
The Skyscraper Sunflower is an open-pollinated tall sunflower variety. This cultivar is a branching type that produces a host of blooms and large green leaves along its long main stalk, making them not only tall but also quite wide in the garden.
Skyscraper Sunflowers grow to reach about 12 feet tall. The flower heads on this variety are about 12″-14″ wide. Skyscraper Sunflower plants are quick growers, taking only 70 days after planting to reach maturity.
4. American Giant sunflower
The American Giant Sunflower is a modern hybrid sunflower variety with an extra-sturdy stalk. These tall plants grow a single heavy sunflower head at the top, yet rarely need staking. They are also very easy to grow.
American Giant Sunflowers grow to reach about 16′ tall in good growing conditions. The flower head at the top can reach 12″ across. This variety takes about 80 days (2.6 months) to reach maturity after planting.
5. Titan sunflower
The Titan Sunflower is an heirloom tall sunflower variety that remains one of the tallest sunflowers available. Selected from the Mammoth Sunflower (described above), the Titan is well-suited to home gardens as it has a sturdy root system and rarely needs staking.
Titan Sunflowers grow to reach about 14 feet tall in good growing conditions. The flower at the top of the main stalk is often about 12″ wide but can reach up to 24″ across. This variety of sunflowers takes quite a while to reach their gigantic height, usually taking about 110 days (3.6 months) to reach maturity after planting.
6. Pike’s Peak sunflower
The Pike’s Peak Sunflower is a tall sunflower variety known for having extra-large sunflower seeds. These towering giants are perfect for a fence line or a garden border.
Pike’s Peak Sunflower plants grow up to 15 feet tall. The flower heads are about 14″ wide and contain very long edible seeds. Pike’s Peak Sunflowers take about 100 days (3.3 months) to reach maturity after planting the seeds.
7. Sunzilla sunflower
The Sunzilla Sunflower is a popular giant sunflower variety for children’s gardens. These tall plants can be grown in a line to create a towering wall of sunflowers. They are well-known for attracting birds and pollinators, as well as for their edible seeds.
Sunzilla Sunflower plants can reach 16 feet tall in optimal growing conditions. The flowers grow to be about 12″ wide. Sunzilla Sunflower plants take about 90 days (3 months) to reach maturity after planting.
8. Kong sunflower
The Kong Sunflower is a newer variety that’s perfect for the perimeter of the garden or along a fence line. This hybrid variety is easy to grow and is a great choice for new gardeners. Rather than producing only one flower at the top of the stalk, this variety grows branches, blooming up along the sides of the main stalk (which is covered in green foliage).
Kong Giant Sunflowers grow to reach about 16 feet tall in good growing conditions. The flowers are about 10″ wide. Kong Sunflower plants take about 80 days to reach maturity after planting.
Planting tall sunflower seeds
Sunflower seeds should be planted outside in the ground as soon as the danger of a hard frost has passed to give them the longest possible growing season (and the tallest possible height. This is usually around March-May in most climates.
For tall sunflowers, be sure to plant the seeds in an area where the leaves of the growing sunflower plant will be in full sun. This means that the plant should receive a minimum of 6-8 hours of direct sunlight each day. Sunlight is required for photosynthesis, which is how the plant is able to grow so tall. Don’t try to grow giant sunflowers in the shade!
Tall sunflowers can be planted outdoors as seedlings, but this is disruptive to their developing roots. For the tallest sunflowers, direct seeding into outdoor soil is recommended instead of transplanting baby plants.
Dig a little hole with a shovel, no more than 1″ deep. Place the sunflower seed in the hole and replace the dirt back onto it. Then water the soil area carefully and watch to ensure that the water penetrates into the earth rather than running off away from the buried seed. Save the seed packet and make a note of the planting date and when the expected bloom time for the flower.
Caring for tall sunflowers
Keep the sunflower seeds watered as the sprouts emerge and begin to take hold. The plant will be more hardy and tolerant of dry soil once the thin stem has formed several sets of leaves. Sunflowers require moisture in order to develop since it aids in the development of each plant cell and helps the plant grow to towering heights.
Water your sunflowers once a week, unless it’s very dry or humid (more so in a very dry climate, and less so in a wet one). Check the sunflower plants on a regular basis for indications of drooping or crisped leaves from dehydration or moisture-related problems like fungus. Sunflowers are quite drought-tolerant once the plants are a few feet tall, but a lack of water will stunt their growth. Water deeply and frequently for super-tall sunflowers.
Some varieties need to be staked, especially in windy climates. Use a sturdy metal stake and tie the main sunflower stalk to the stake with twine at approximately 2-foot intervals.
For gardeners with soil poor in nutrients, a high-quality organic fertilizer can also help your plants grow tall. Slow-release granular fertilizers are easy to apply, but you can also use quick-acting water-soluble types. You can also apply a surface layer of 1″ of compost around the base of the plant as a mulch for a nutrient boost that can also help suppress weeds and moderate soil temperature and moisture.
Watch your sunflowers bloom in late summer and take note of the many beneficial pollinators and other creatures that visit them. Bees, butterflies, and more wildlife are attracted to the bright yellow petals and brown centers full of pollen.
Many varieties of tall sunflowers, especially the heirloom types like Mammoth, have delicious seeds which can be harvested in the fall for a healthy snack. Harvest sunflower seeds before the birds discover them and try them roasted with a bit of salt!