21 Varieties Of The Tallest Sunflowers You Can Grow In The Garden

Gardening may be described as an activity that invokes serenity, but for breeders, it often signifies a purpose or a challenge. If you're neck-deep into the gardening world, you might have heard of a Fort Wayne-based landscape gardener breeding the world's tallest sunflower to date. Named 'Clover,' this hybrid variety has grown over 35 feet at the time of measurement and is still increasing — a massive, thrilling achievement, indeed. This naturally made us think about other sunflower varieties that grow to enormous sizes and can be cultivated by home gardeners. It turns out there are several options, including 'Sunzilla,' 'Mammoth,' 'Russian Mammoth,' 'California Greystripe,' 'Titan,' and 'Autumn Beauty.' While they don't reach 30 feet, they're sure to dwarf you in size, as they can mature to heights of 8 feet or more.

But before we delve any deeper, remember that growing tall sunflowers requires some planning — you can't willy-nilly scatter their seeds, hoping they'll sprout on their own. Instead, approach this systematically by starting seeds indoors and transplanting the most vigorous seedlings outdoors as soon as the soil is workable. Space them at least 2 feet apart. Otherwise, poor air flow can encourage disease. Choose their location carefully as well. You can't plant them near low-growing, sun-loving plants, as they'll be shaded by the sunflower stalks. Additionally, you'll need enough room to erect stakes to prevent the blooms from flopping over. With that established, let's explore some of the tallest sunflowers on offer in the horticultural trade for home gardeners.

Bred by UK-based Victoria Wakefield for over 30 years, the 'Giraffe' sunflower (Helianthus annuus 'Giraffe') can reach an imposing 17 feet in height. This has to do with the plant blooming late into the growing season when the days grow short, enabling it to gain more height. The treasured flowerheads make an appearance around late summer or early fall to the utter delight of bees and birds, who are starved of other food resources around this time. However, to ensure this sunflower achieves its maximum potential, get it into the beds in spring and fertilize judiciously.

Planted between April and June, depending on when your area experiences the last of its frosts, 'Sunzilla' (Helianthus annuus 'Sunzilla') can grow over 12 to 16 feet tall within one growing season. Ideal growth temperatures sit between 55 and 95 degrees Fahrenheit, making them ideal for zones 3 to 10. With full sun exposure, consistent watering, and lots of fertilization, expect this giant plant to blossom huge yellow heads in under 90 days. If you're planning to add them to your vegetable garden, team them with cucumbers or melons whose vines can climb up the tall stalks of sunflowers.

'American Giant' (Helianthus annuus 'American Giant') sunflowers make a striking appearance in sunny gardens with their 15-foot-tall stature. Around summer, a bright yellow, 12-inch-wide flower sways atop heart-shaped, dark green foliage. Neutral to alkaline soils are preferred, and clay soils are tolerated if necessary. Ensure proper drainage and ample sun exposure, or nuisance pests, such as slugs and snails, may kill the plant. Since they're heavy feeders, it's best to work compost into the soil before planting. 'American Giant' produces a sturdy stalk that can do without support in a sheltered location.

Capable of growing over 15 feet high, the 'Pike's Peak' sunflower (Helianthus annuus 'Pike's Peak') is an excellent addition to exposed areas in your garden. Its thick stalks give the plant ample support, though staking is appreciated. Unlike most tall sunflower varieties, these are multi-headed, producing about 14 flowerheads in a season. The greenish-brown disks draped in bright yellow petals carry over 1½-inch-wide seeds — possibly the largest for any sunflower. These frost-tender plants are in bloom from July to September if directly sown or transplanted in beds during early spring.

Like its namesake, the 'Kong' sunflower (Helianthus annuus 'Kong') can shoot nearly 15 feet high — 8 feet when the conditions are sub-par. It sprouts a lush, green mass of heart-shaped foliage, out of which several branches of 10-inch-wide yellow flowers pop out in the middle of the summer. You may either grow this annual as an accent or plant it en masse over 3 feet apart to create a flowering hedge. For a hedge, however, pinch the stems around the 5-foot mark so the plant becomes bushy. 'Kong' doesn't produce pollen and can be used in indoor arrangements.

'Arikara' sunflower (Helianthus annuus 'Arikara') can top out at 12 feet but has a variable form, producing a single stalk or a bunch of flowering branches (which you may prune if you want the single form). The bright flowerheads have a diameter of 16 inches, while the brown discs are chock full of edible seeds. This is why this variety was widely sought after by the North Dakota-based Arikara tribe. These fast-growing annuals mature in under 70 days when started with seeds. They need about eight to 12 hours of direct sun exposure for the best growth.

With flowerheads that can be 2 feet wide, 'Titan' (Helianthus annuus 'Titan') sunflowers will become the talk of the town when they fully mature. When given about eight to 12 hours of direct sun exposure and moist, organically rich soils, these plants will surprise you with brown-eyed, yellow flowers in mid-summer. Started after frost, they mature in under 110 days and grow between 12 and 14 feet high. You can even make your own birdseed by growing these beautiful plants in your garden — snip their dried heads, dry them, and pick the plump-looking seeds.

Topping over 12 feet (14 feet if the growth conditions are optimal), the 'Mongolian Giant' sunflower (Helianthus annuus 'Mongolian Giant') is an annual variety you can easily grow in gardens. In the summer, the stalk supports a classic sunflower that's often 18 inches across. The seeds are of a considerable size and can be saved for consumption or left out for backyard birds. 'Mongolian Giant' is a fast grower, gaining over 1 inch of growth daily. So, even if you delay the planting until summer, you can still expect to see a tall plant. Watch out for slugs.

'Skyscraper' (Helianthus annuus 'Skyscraper') is a single-stalked sunflower variety that towers 12 feet high by maturity. The yellow-petaled flower in question is 14 inches wide and shows a host of golden-green seeds that birds find attractive, and you may harvest and eat them after roasting. Seed-grown plants mature in 75 days and bloom all summer long, keeping the area's bees busy. To avoid adding stakes, grow them along a fence or a wall, provided they're exposed to ample sunlight throughout the day and housed in well-draining loamy or sandy soils. Protect the seedlings from slugs by putting down barriers.

In optimal conditions, the 'Mammoth' (Helianthus annuus 'Mammoth') sunflower can grow nearly 12 feet tall. In summer, the green stalks are topped by almost 1-foot-wide yellow flowers. Both birds and squirrels delight in these seeds, so be prepared to cover the heads in plastic bags as they dry out, in case you wish to preserve a few for your midnight snacking. 'Mammoth' sunflower exhibits excellent heat and drought tolerance and can be popped at the back of annual beds in zones 2 to 11 or massed into a living hedge. You don't need to fertilize this sunflower variety unless you're dealing with poor soil.

'Russian Mammoth' sunflower (Helianthus annuus 'Russian Mammoth') is another giant sunflower variety that can mature to heights between 9 and 12 feet. In mid- or late summer, these annuals are decked in approximately 14-inch-wide, bright yellow flowers that you may cut for floral arrangements. As butterflies, bees, and birds enjoy their nectar and seeds, these make excellent additions to pollinator gardens. Although they're unconcerned about pH levels, performing just as well in alkaline soils, high organic content, and good drainage are a must. Bonus advantages: Deer dislike their foliage, and their grayish-white seeds are edible.

In ideal conditions, 'Autumn Beauty' (Helianthus annuus 'Autumn Beauty') can grow between 9 and 12 feet high. Avoid growing it in fertile or nitrogen-rich beds, or you won't get to see many flowers. When the danger of frost is past, directly sow the seeds in the soil for a pretty harvest and bee food in 85 days. Keeping to its name, the flowers on 'Autumn Beauty' show a blend of autumnal shades, including bronze, red, and orange. So, if you would like to enjoy them until frost or use the edible petals in salads, successively sow seeds every three weeks.

Adorned in classic chocolaty-eyed, yellow flowerheads, 'Mammoth Grey Stripe' sunflowers (Helianthus annuus 'Mammoth Grey Stripe') can be as high as 12 feet, or just short of 8 feet if grown in less-than-optimal conditions. Their 1-foot-wide flowers make the plant top-heavy, necessitating staking or planting alongside suitable companion plants, like lupines, that can support their weight. To minimize disease pressure, make sure to plant these annuals about 4 feet apart (their mature width size). Seeds are edible and can be safely consumed as snacks, assuming finches leave any. This heirloom variety is in bloom from summer through fall.

Looking for a show-stealer for your fall garden? Giant sunflower (Helianthus giganteus) may just be it. Indigenous to the areas east of the Mississippi River, this giant plant can grow nearly 10 feet tall, sometimes reaching up to 12 feet. Since it quickly creeps along the ground via rhizomes, it can colonize the space, making it unsuitable for small yards. If you don't want it to become aggressive in the landscape, plant it in average soils or in unfertilized beds. From July through September, bright yellow flowers stand atop purple stems in zones 3 through 9.

'Giant Primrose' sunflower (Helianthus annuus 'Giant Primrose') can grow 12 feet tall in average garden soils and exhibits decent resistance to heat and drought. Since it takes only about 75 to 90 days to fully mature when grown from seeds, continue to plant it well into early summer if your growth season is long enough. In this case, you should directly sow it in the ground, as the seedlings don't transplant well. Another plus? These plants produce self-pollinating flowers that brighten a garden with effortless color, even if bees and flies are inactive.

Those looking for plants that you and your child can grow together should give 'Premier California Greystripe' sunflower (Helianthus annuus 'Premier California Greystripe') a shot. When their huge seeds are sown in early spring, these plants fully mature in about 80 to 120 days, glowing bright with 10-inch-wide, goldenish-yellow flowerheads. They're usually touted as an improved version of 'Russian Mammoth,' because their seeds exhibit a more uniform color, not that the birds would care, because the seeds are delicious regardless. They can grow between 6 and 8 feet high. Caterpillars may tatter their foliage mid-summer.

Sunforest Mix, a Burpee Seeds collection, isn't a single variety. Instead, it's a mix of three different varieties that together grow between 10 and 15 feet high. All blooms grow over 1 foot across, giving your summer-scape an instant lift. For the maximum impact, eke out a separate block where you mass plant this selection, spacing each plant at least 4 feet apart. Plant wider if creating a sunflower forest, so there's adequate space to squeeze in between the towering stalks. Be sure to offer full sun exposure and well-draining soils.

Break away from the conventional chocolaty-yellow mold of sunflowers by growing 'Candy Mountain' sunflower (Helianthus annuus 'Candy Mountain') instead. These annuals bear burgundy-pink petals that fade away into yellows atop hairy, green stems, injecting sizzling drama into the garden beds. As for their habit, each leafy node turns into a branch, producing a mountain of several single-stalked junior plants. 'Candy Mountain' can grow about 9 to 10 feet tall and is great for adding vertical interest to low-growing ornamentals. It performs well even in poor soils and can tolerate dry conditions, as it is slightly drought-tolerant.

With full sun exposure, the 'Treasure Mountain' sunflower (Helianthus 'Treasure Mountain') can be successfully grown both in dry and moist beds. This hybrid variety is very floriferous and produces a dozen flowering stalks if spaced right (about 3 feet). 'Treasure Mountain' is particularly prized for its saturated golden hues that really pair well with other ornamentals in summer beds. These self-fertile plants can grow about 8 to 10 feet tall. Consider cutting a few flowers for vase arrangements while leaving the rest for the local pollinators.

Another hybrid that breaks away from the norm, the 'Zeus' sunflower (Helianthus annuus 'Zeus') produces huge, lemony-yellow flowerheads that can be nearly 12 inches wide. After the last frosts have passed, directly sow the seeds in the spring soil and prepare yourself to be bedazzled by their sunny power after three months. These plants remain in bloom for about four to six weeks. When using these sunflowers as screens, space the plants about 1 to 2 feet apart. As they can grow 8 feet high, they're placed at the back of borders and beds.

What sets the 'Tarahumara' sunflower (Helianthus annuus 'Tarahumara') apart from its brethren is that, rather than black, it produces white seeds. In addition, its flowery discs are a musty green and not the chocolaty brown most gardeners are conventionally used to. Collected by the Tarahumara tribe, hence the name, this heirloom variety can grow between 8 and 10 feet high. Since the seeds fully mature in under 100 days, you can continue to sow this plant well into summer if you've a long growing season. The mature flowers often nod downward, preventing the birds from gaining a foothold and accessing the seeds.