With their iconic vibrant petals and reputation for hardiness, it’s no wonder sunflowers are one of the best selling flowers year after year. These easy to grow plants come in numerous varieties depending on what colours and sizes you need for your garden or arrangements. If you’re ready to add this staple to your summer garden, this post covers everything you need to learn about how to grow sunflowers.
Sunflowers just might be the perfect low-maintenance yet eye catching addition to your garden. These striking plants are a staple, and they’re easy to grow.
You’ll find sunflowers at the florist stand of your local farmers market and lining fences in your neighbourhood during the heat of summer into the early fall.
While the bright yellow flowers of the common sunflower (or Helianthus annuus) are classic, different variations can add contrasting colours to your garden. You can even grow a variety of sizes, making them a great choice for arrangements!
Here’s what I’ll be talking about today…
Meet the Sunflower
Native to North America, sunflowers are best known for their vibrant yellow petals, which resemble rays of sunshine.
Besides their decorative function, sunflowers can be used to increase the production of other crops, such as corn and squash, in a method similar to the Three Sisters’. This is a method of companion planting that indigenous people of North America have been doing for thousands of years.
When it comes to learning how to grow sunflowers, there are two types you should know: single-stem and branching.
Single-stem or non-branched sunflowers are recognizable by their long, straight stems, which make them useful for floral arrangements. These plants produce one flower per seed, and the sizes can vary depending on how far apart they are planted. Species of single-stem sunflowers include the Marley and Procut Bicolour varieties, as well as the Sunrich Series.
Branching sunflowers, which include the Chocolate, Greenburst, and Starburst Panache varieties, produce more flowers over a longer period of time, with multiple stems in a more bushy growth pattern. As a result, they require more room to grow.
There are also some species of perennial sunflowers.
If you are hoping for a garden that doesn’t require planting each year, these would be a great option. Though smaller than the large yellow blooms you’re used to, perennial sunflowers can still add a pop of brightness to your low-maintenance garden.
How to Grow Sunflowers
Whether you’re hoping to add a festive touch to an already established garden or sowing your first seeds, their beauty and hardiness make sunflowers a great choice. If you’re ready to get planting, this grow guide has everything you need to know.
When and Where to Plant Sunflowers
Though sunflowers are typically associated with the late summer and early fall, they can be planted in the spring as soon as the weather warms up and frost is no longer a concern.
I prefer to get my sunflowers started inside due to the fickle nature of spring in Canada and the abundance of slugs in my ecosystem. If you’re doing the same, plant your seeds 2-3 weeks before you plan to transplant them into the garden. You’ll know they’re ready to be moved outside, when your sprouts are 3-5 inches tall.
You can also plant your seeds directly in your garden. I find that when I directly seed them, either the birds eat the seeds or the slugs eat the sprouts. So make sure to protect them with netting or a cloche until they are about five inches tall.
Whether you’re planting inside or outside, make sure to fully cover your seeds with soil, as sunflowers (ironically) sprout in the dark.
Sunflowers don’t require any special soil, so whatever garden or potting soil you’ve got will do.
Light
As the name suggests, sunflowers need plenty of light. In order to thrive, they require at least 8 hours of direct sunlight. That shady spot next to your fence is not the place to plant these light-loving flowers.
Water
Sunflowers require the most water after they’re first planted, so water your sprouts often to keep the soil damp.
After your sunflowers are established, they are considered a low-maintenance, drought-resistant plant. Water them regularly, but don’t worry if the soil dries out between waterings. During intense heat, they may need some extra moisture.
Pruning
If you’re growing single-stem sunflowers, there is no need to worry about pruning.
For branching varieties, I recommend pinching your plants back to 4 leaves once they grow to be 12-18 inches. If you’re harvesting your sunflowers, cutting the blooms from the base of the stem can also help encourage new growth.
Common Pests and Diseases
Your sunflowers are most vulnerable in the early stages of germination. This is one reason to consider starting the seeds indoors and transplanting them into your garden.
However, if you’ve opted to plant your seeds directly in the ground, covering the sprouts can help protect them from birds, deer, and other animals. I like to use lightweight netting or cloche, but any sort of chicken wire or fencing will do the trick.
I also recommend changing where you plant your sunflowers each year to help prevent disease.
How to Grow Sunflowers in Containers
Planting sunflowers in pots can be a great option if you have limited outdoor space.
Many varieties will grow well in a container or bag as long as it has drainage holes. Just keep in mind these sunflowers will be smaller than those planted directly in the ground.
Look for shorter dwarf varieties such as this blend from West Coast Seeds.
How to Harvest Sunflowers
If you’re growing sunflowers in hopes of decorating your kitchen table, I highly suggest choosing a pollen-free variety to save yourself the cleanup and avoid ruining that new pastel tablecloth.
You can harvest your sunflowers as soon as the first petals start to unfurl. To extend the life of your sunflowers without adding any chemical preservatives, make sure to remove the leaves from the stem, leaving only the top leaf.
Your beautiful sunflowers will last about a week in a vase. Keep in mind that a warm environment will speed up the flower’s opening. If you’re saving them for a specific occasion, you can place them in a cooler area of your home to slow down the blooming process.
FAQs About Growing Sunflowers
Do sunflowers really track the sun?
While sunflowers do respond to light, they don’t move in the way you’re probably picturing. In other words, their heads do not rotate throughout the day along with the sun.
Contrary to popular belief, sunflowers only respond to light before they flower. During this stage, more growth occurs on the sunniest side of the stem, causing the flower to eventually tilt to one side, usually east.
How far apart do you plant sunflowers?
Spacing your seeds correctly is an important part of learning how to grow sunflowers. For branching sunflowers, 18-24 inches is the ideal space between seeds, as these types of sunflowers grow large quite quickly.
The spacing of single-stem sunflowers is up to you, as you can control the size of your sunflower blooms by changing the spacing of seeds. I find leaving 4-6 inches of space between seeds gives me the perfect flowers for bouquets. If you’re hoping for larger sunflowers, just space your seeds out more.
What is a good sunflower germination temperature?
Sunflower seeds like warm soil temperatures of about 21-25℃ for optimal growth. Make sure to wait until the weather has warmed and the overnight frost has passed. If you live in a cooler climate like I do, you may want to consider starting your seeds inside.
How long should it take for a sunflower to grow?
Once your seeds are in the ground or a pot, it won’t take long for them to start growing. You’ll likely notice sprouts poking through in just a few days.
From there, depending on the variety, your sunflowers will start blooming 2-3 months later. Some types of sunflowers take up to 110 days to grow flowers.
