How to Grow Sunflowers

by Matt Gibson

Let’s grow sunflowers! Sunflowers (Helianthus annuus) are not just an eye-catching summer flower that makes a natural choice as a showy standout in any flower garden. Sunflowers have many useful attributes aside from simply being pretty, and they are a common sight in gardens around the world for good reason. These flowers produce sunflower seeds by the truckload, and those seeds are a nutrient-rich snack that humans, birds, and other animals can enjoy.

Sunflower oil can also be harvested from sunflowers, and it has many uses in the kitchen. The sunflower’s oil is also an ingredient that can be put to use  in soap making and cosmetics. Sunflowers attract birds, bees, and other beneficial insects to your garden getaway which will help with pollination and pest control issues. The largest sunflower varieties can also be used as windbreaks and as support plants for pole beans and other plants that can use a bit of stake support when in full production.

The other perk many gardeners enjoy about growing sunflowers is the lack of effort that’s needed to encourage these garden giants to thrive. Despite their spectacular size, sunflowers are one of the easiest plants to grow. These bright beauties stand up well to heat and are also drought tolerant and resistant to most pests and diseases. Once they get going, sunflowers require very little care to thrive. In fact, over-fertilization is one of the only problems gardeners tend to face when growing sunflowers, as too much coddling can lead to stem breakage when the flowers start to grow larger and larger.

Despite the stereotype, not all sunflowers are yellow giants that will tower over the rest of your garden’s goods, though many do grow as high as 15 feet tall and have massive flower heads that can span a foot from one side to the other. Sunflowers are also available in medium-sized varieties that reach five to eight feet tall with eight- to 10-inch blooms, and there are also dwarf sizes on the market that only reach one or two feet in height. It’s true that the most common sunflowers are bright yellow in hue, but petal colors can range from burgundy or red to orange and yellow—and everywhere in between.

No matter which type of sunflowers you choose to grow, you’ll want to prepare yourself with these tips and directions. Sunflowers are sure to give your garden the showy style you’re looking for and set your beds apart from the others on the block. After planting sunflowers, you’ll also be able to stock your kitchen and bird feeders up with tasty, nutritious sunflower seeds for years to come.  

Sunflower Varieties

Mammoth: The iconic Mammoth variety is a giant yellow sunflower that is most widely grown and often harvested for sunflower seeds. These towering flowers of power can grow up to 15 feet high with spectacular flower pods that span a foot in width. 

Autumn Beauty: These medium-sized sunflowers grow up to seven feet tall and have six-inch flower heads. They are available in the traditional yellow shade as well as more unexpected tones, such as mahogany and bronze.  

Sunbeam: The Sunbeam variety, which Vincent Van Gogh popularized in his famous painting, grows around five feet tall, and its blooms are five inches wide with the traditional yellow hue.

Teddy Bear: This smallest variety of sunflower boasts five-inch blossoms in a deep golden shade of yellow set on stalks that grow anywhere from two to three feet high.

Growing Conditions for Sunflowers

Sunflowers, as their name suggests, enjoy a whole lot of sunlight. If possible, plant them in full sun on the northern side of your garden so that taller plants (if you’re growing any taller plants) don’t block the sunlight from reaching your sunflowers’ faces. Great soil will produce great-looking sunflowers, to be sure, but they’re luckily not very picky, so gardeners don’t need to worry too much about soil conditions. For optimal performance, sunflowers prefer a slightly acidic soil with a level around 6.0 to 7.5 pH, but again, they are not fussy about soil and will grow just about anywhere. Just be sure that their area has sufficient drainage, as waterlogged soil can lead to all kinds of problems all throughout your garden. Sunflowers are heavy feeders, so be sure to add in some organic matter or composted manure when preparing your planting site. 

How to Plant Sunflowers

Plant sunflower seeds or transplant seedlings around the time of the last frost when the soil has begun to warm up a bit. Dig the soil to loosen it before planting about two feet deep, leaving spaces three feet across between specimens, as sunflowers have long taproots that need to stretch out for prolific growth. You may consider adding a slow release granular fertilizer about eight inches into the soil around the plant site, but be careful not to over fertilize, as doing so can lead to stalk breakage as your sunflowers grow tall.

Growing these tall plants near a fence or building is ideal to protect the giant blooms from being damaged in heavy winds. Plant large sunflowers in rows 30 inches apart, placing each seed one inch deep and six inches apart from each other to allow your plants plenty of breathing room during the sprouting period. You might consider staggering the planting of some of your sunflowers across five to six weeks so that you will see continuous blooms over a longer period of time as they mature. Another thing to consider is that sunflower seeds can quickly kill off grass when they fall to the ground, so make sure to plant sunflowers a good distance away from any grass that you take pride in.    

Care of Sunflowers

When sunflowers are small, water around the root zone at a distance of three to four inches away from the plant. Once they are more established, you can water sunflowers deeply but infrequently to encourage strong, healthy root systems. Unless you have experienced a lot of recent rain or had a drought in your area,  you should water each plant once per week with several gallons of water. Fertilize sunflowers very sparingly, and add bamboo stakes for support once the large varieties begin to get too tall to stand upright on their own accord.

Garden Pests and Diseases of Sunflowers

Sunflower seeds are a favorite snack of birds, squirrels and deer, so unless you don’t mind sharing your harvest, you may want to put wire or polyspun fleece barriers in place to prevent seed theft. Feasting birds will also make a mess of your garden, throwing sunflower seeds all over the ground. If you love having bird guests in your garden, you might consider harvesting sunflower seeds as soon as possible and putting them in a bird feeder to keep your planting area nice and neat. Sunflowers don’t experience a lot of pest issues. However, every now and then, small gray moths will lay eggs in the blossoms. Check the blooms once per week, and pull any worms out when you spot them. Sunflowers are generally very healthy and hardy plants, but there are a few fungal diseases that can give them some trouble. Downy mildew, rust, and powdery mildew are a few of these maladies that target sunflowers, but each of these is easily treatable by spraying on a general garden fungicide.

Harvesting Sunflowers

Keep an eye out for seed ripeness when it gets close to harvest time. The back of the flower head will turn from green to yellow and the seeds will start to brown when they are ready for removal. This change usually occurs about 30-45 days after blossoms opened. Cut the bloom down by trimming off the head about four inches below the blossom, then remove the seeds with a fork or your fingers. If birds stealing your seeds are a problem, you can cover the seed pods with a cheesecloth—or cut down the blooms early and hang them upside down indoors until the seeds are ready for harvest.

Indoor Bouquets

Early in the morning is the best time to cut sunflower heads off the main stems. Do this right before the flower buds open. This will encourage side blooms to pop up in the place of the main bloom,extending the life of the cut sunflowers. Performing the cutting during cool morning hours will help protect against possible wilting. Gently construct your bouquet in a tall vase, and fill the container with room temperature water. Change the water out daily, and make sure to choose a vase that will help support the stem against the weight of the massive sunflower pods. The sunflower should last at least one week before it begins to wilt.   

Videos About Growing Sunflowers

Like the giant sunflowers the most? This video details how to grow, harvest and maintain the biggest sunflowers available:

This helpful video shows you how to improve your garden’s soil conditions using mini sunflowers:

Not convinced that sunflowers are the right choice for you? Check out this video that informs you of the many reasons why growing sunflowers is a great choice:

Want to Learn More About Growing Sunflowers?

The Farmer’s Almanac covers How to Plant, Grow and Care for Sunflowers

Burpee covers All About Sunflowers

Gardening Know How covers Growing Sunflowers in Your Garden

Good Housekeeping covers The Best Way to Grow Beautiful Sunflowers and Harvest the Seeds

HGTV covers Growing Sunflowers: When to Plant and How to Grow Sunflowers