I love sunflowers—I mean, who doesn’t? They’re easily one of the best-marketed flowers globally—and you’ll find photos and emblems of them on everything from real estate brochures and biology textbooks to designer wear and summer dresses. And although they’ve become pretty pervasive in human aesthetics and culture—even symbolizing the dream of a nuke-free world—very few pay attention to how they grow.
Sunflowers need to be pollinated to produce seeds. Like many other flowering and seed-producing plants, sunflowers can cross-pollinate or self-pollinate. However, some sunflower varieties are pollenless and do not produce seeds.
I wrote this article to answer questions about pollination in sunflowers and discuss crucial points about the development of sunflowers. Keep reading to learn how sunflowers grow and produce seeds, the best varieties to keep in your garden, and how to grow and care for them correctly.
Do All Sunflowers Produce Seeds?
Sunflowers are native to the North American continent and have been cultivated by Native Americans since 1000 B.C. Their recent popularity is mainly a result of European exploration during the 1500s, and today, they’re primarily grown for their seeds as much as for their beautiful petals. However, the plant’s physiology can confuse amateurs.
Not all sunflowers produce seeds. Many varieties do not produce seeds—these are called pollenless sunflowers. Pollenless sunflowers are mutated sterile male sunflower species incapable of making seeds independently and cannot fertilize other sunflower plants.
Pollenless sunflowers are genetic mistakes that were discovered in the mid-1900s by chance, but they’ve officially been available to the general public since 1988. Although the idea of non-reproducing sunflowers might seem like the start of a lousy apocalypse movie, these pollenless varieties are important to many growers.
Even though farmers have been tinkering with plants and animals for thousands of years, pollenless sunflowers are a naturally occurring variety. Since their introduction to gardens worldwide, these seedless sunflowers have seen widespread adoption due to the fact that they don’t produce pollen during their development.
They are especially favored by gardeners that suffer from pollen allergy and enthusiasts looking to grow the plant exclusively for decorative reasons. However, widespread cultivation of the plants, especially in the wild, is usually criticized, as they offer very little to insect populations in their habitats.
Most insects, particularly bees, rely on pollen and nectar for their dietary needs. And while pollenless sunflowers are still excellent sources of nectar, bees will have to find other sources to get protein-rich pollen for their diet.
You can tell if your sunflower is pollenless by running your hand across the flower to check for pollen or examining the plant for signs of husks during its reproductive stage. If there are no signs of husks, you’re most likely working with a pollenless sunflower.
I recommend asking an experienced gardener or the shop where you purchased your seeds for a more conclusive opinion.
Pollenless sunflowers come in different varieties, shapes, and sizes. If you plan on growing one in your garden, you have more than enough options. They even come in different colors, ranging from the familiar yellow to adventurous green.
Some of the most popular pollenless varieties include Munchkin, Joker, Sunbeam, Bashful, and Double Dandy. It’s also common to see species like Starburst Lemon Aura, Zebulon, and Firecracker in many gardens.
How Do Sunflowers Grow?
Sunflowers (Helianthus) include dozens of species that come in many shapes, colors, sizes, and varieties. However, the most easily recognized species is the Helianthus Annuus, with its distinctive full yellow petals and yellow to black center (stamens). Like many plants, sunflowers need soil to grow and will flourish with minimal care.
Sunflowers grow from seeds, and it typically takes 12 to 14 weeks for the plant to fully mature from the seed stage. They are easy to grow but require 6 to 8 hours of sunlight daily, slightly alkaline soil, and a good water supply. Sunflowers typically thrive in soil with a pH of 6.0 to 7.5.
Sunflower plants start their life from an initial germination phase, optimally during mid-April to late May. They develop their roots systems during this time. The germination phase typically lasts for 8 days, enough time for the plant to grow shoots that break through the ground in search of sunlight.
The next phase is the vegetative phase. Sunflowers will grow as seedlings during this stage. The vegetative state usually lasts for 10 to 13 days after germination, and the plant will form its first leaves if it’s growing properly.
Afterward comes the reproductive phase. As you’d suspect, it’s at this stage the sunflower plant forms buds that will grow into the characteristically yellow blooms. Sunflowers take about a month to bloom, and it’s common to see fields of yellow in July and August.
Sunflowers bloom for approximately 20 days. This time is sufficient for pollinators to do their job and fertilize the plant’s seeds. You’ll know the blooming phase is coming when the plant’s head begins to turn a lovely yellow.
The final stage in the growing cycle of a sunflower is the harvesting phase, and you’ll know the plant has reached this stage when it droops and turns a darker shade of brown. You can harvest sunflower seeds by cutting off the plant’s head and storing it in a suitable bag.
Of course, pollenless sunflowers go through all these phases but do not produce any seeds for you to harvest. Sunflowers are annual plants, and you’ll need to replant them every year if you want to keep them. Don’t worry; they usually produce more than enough seeds to start in the next growing season.
All varieties of sunflowers can grow in almost any part of the world. The reason is simple—sunflower plants are hardy, develop extensive and efficient tap root systems, and mature fast enough to brave extreme conditions.
In addition, while some flowers might shy away from the sun’s glare, sunflowers thrive in it. Most sunflowers will wither or grow pretty awkwardly if they do not get at least 6 hours of sunlight every day.
They are so sun-loving that young sunflowers will “track” the sun’s movement to ensure their petals get as much sunlight as possible. Older plants typically stop this tracking and grow with their blooms facing east, perfect for catching the first—and best—hours of sunlight.
Of course, this practice and their round shape and bright yellow colors are why they’re so aptly named.
How to Grow Sunflowers
You can quickly grow your sunflowers as long as you have access to healthy seeds, well-draining soil, and at least six hours of sunlight every day. Sunflower gardening is pretty simple since the plants do not require a lot of tending. But you’ll need to monitor and control the environmental conditions to ensure the plants thrive.
You can use a pot for sunflowers, but I recommend planting them directly in the earth.
Here’s how to grow sunflowers:
1. Get Healthy Seeds
Get healthy sunflower seeds from the year before or from a flower shop. Alternatively, you can get them from online stores. I recommend getting mammoth sunflower seeds if you’re unsure of what variety to get. These seeds grow into sturdy plants that can reach a height of up to 12 feet (3.7 meters).
2. Find a Suitable Spot in Your Garden
Find a suitable spot in your garden for your seeds. Remember that the site you choose must get 6 to 8 hours of sunlight every day if you want the sunflowers to thrive. You can also use a planter with drainage holes.
3. Make Holes and Place the Seeds
Make holes approximately 1-inch (2.5 cm) deep and place the seeds. Remember to keep a space of 4 to 6 inches (10-15 cm) between each hole.
4. Add Some Fertilizer
Add some fertilizer if the soil needs it. Remember to check that the soil pH stays between 6.0 and 7.5. I recommend using a pH meter to monitor the soil’s pH.
5. Plant a Few More Seeds to Increase the Likelihood of Success
Plant a few more seeds every two or three weeks to boost the likelihood of success and increase the number of blooms you’ll have. Seeds can fail, and spreading the planting this way will ensure your garden is filled with many sunflowers during the blooming season.
6. Water Around the Roots
Water around the roots when the first leaves start growing. Watering is essential, but take care not to water the plant directly. I recommend watering once a week, but the ideal watering frequency will depend on the weather.
7. Add a Stick for Support
Add a stick for support if the plant needs it. Some taller sunflowers may require assistance to grow, and you can use a stick or cane as support.
Harvest the sunflowers. Cut off the plant’s head about 2 inches (5 cm) below the bloom to harvest the sunflower seeds. You do not have to harvest pollenless varieties since they don’t produce seeds.
Best Time for Planting
The best time to plant sunflower seeds is between April and May. I’d recommend waiting no later than late May so that the seeds can start germinating in the right conditions.
Sunflowers need to be pollinated to produce seeds, but many pollenless varieties do not produce seeds. These sunflowers do not need pollination, but they still grow beautiful flowers. Many growers prefer these pollenless varieties and keep them exclusively for ornamental reasons.
This article is a friendly enough guide if you’re looking to get into sunflower gardening or if you’re curious about sunflowers. Although sunflower gardening might seem daunting at first, you can be sure of beautiful blooms if you follow this guide.