Sunflowers: Complete Guide How to Grow and Harvest
This post may contain affiliate links, please see our privacy policy for more information.
Sunflowers hold a lot of strong memories for many of us! I have always been a fan of these bright, happy flowers that look like a fluffy lion’s mane. Sunflowers symbolize the sun, and they even follow its path in the sky throughout the day, a phenomenon known as heliotropism.
In this guide, I am sharing my tried-and-true tips as a Master Gardener and retired flower farmer on how to grow and harvest beautiful sunflowers!
what are sunflowers?
Sunflowers, or Helianthus annuus, is an annual plant that has a generally large flower head with a similar shape to a daisy. Sunflowers are a representation of the sun, which is where the get their name. They come in various warm shades, but they are generally light to bright yellow to deep orange. You can also find red, maroon, and brown colored sunflowers! Most commonly, sunflowers are a deep, bright yellow color with a dark brown center.
Sunflowers produce edible seeds that are delicious for snacking or using as bird feed. They are also beautiful cut flowers that will last for a long period of time in the vase, usually over a week!
how long does it take sunflowers to bloom?
There are several different types of varieties of sunflowers, and some of them bloom more quickly than others. There are single stem varieties that only produce one flower head, or maybe two or three, and there are branching varieties that continue to produce flowers after the first blooms are cut.
Most sunflower varieties bloom after 70 to 95 days. Sunflowers grow to be very high with some varieties towering at 16 feet tall! This makes them an excellent plant to utilize for some structural variety in your garden.
how to plant sunflowers:
Before you begin planting out your sunflowers, you will need to know a little bit of information on how, where, and when to plant them!
WHERE TO PLANT SUNFLOWERS:
Sunflowers love the sun! Who knew, right? Sunflowers need 6 to 8 hours of sunlight per day to grow successfully. That means a shady spot in your yard will not work well.
Sunflowers can easily blow over in strong winds. It can be helpful to plant them near a fence or the side of a building. If you plan to plant lots of sunflowers, planting them close together in a block shape can be helpful so that they can lean on each other!
If you are concerned about soil, sunflowers do better in soil that is nutrient-rich, but they can grow in just about any type of soil. If you can, amend your soil with some compost in the spring before planting to help give the flowers all of the nutrients they will need!
when to plant sunflowers:
Sunflowers can be planted as soon as the last frost date for your zone has passed. They prefer hot weather, so do not plant them if there are still light frosts predicted in your area. The soil should have warmed to at least 50° F (10° C) before sowing your seeds.
After the last frost date, sunflowers can be planted in successions every 10 days or so until about 2 months before your first fall frost date. For me in Zone 5b, that’s about every 2 weeks from early May to early August!
how to plant sunflowers:
Plant your sunflowers in freshly tilled soil about 1 to 1 1/2-inches (2.5 to 4-cm) deep and about 6-inches (15-cm) apart. I like to plant my sunflowers rows about 12 to 18-inches (30 to 45-cm) apart. Most seed packets will recommend a farther plant spacing, but this is not ideal if you plan to cut your sunflowers for arranging in vases. The farther apart your sunflowers are planted from each other, the larger their stems will be. Some will become as thick as a broom pole! For smaller stems, plant your sunflowers closer together.
When the sunflowers are about 6-inches (15-cm) tall, thin them out and leave the strongest looking contenders growing in the soil.
caring for sunflowers:
You may notice birds scratching around where you planted your sunflowers. They love to eat sunflowers seeds! If this is an issue, you can cover where you planted the seeds with netting.
Once the sunflowers have popped up, you will want to maintain them by watering regularly at the roots. They do not need a lot of water once they are firmly established, just when the soil has become hard and dry. You will want to try to water as deeply as possible so that they can last on it for longer periods of time. Drip irrigation can be helpful with this!
If your sunflowers are top heavy, you can place bamboo stakes near them and tie the stalks to the stake for support.
how to harvest sunflowers & sunflower seeds:
Harvesting sunflowers is rather easy! For most flowers, it’s recommended that you harvest in the early morning or evening hours. The sun can strip a lot of the plant’s energy and water away. When you harvest flowers in the middle of the day, they have a higher chance of wilting.
Personally, I have harvested all kinds of flowers at various parts of the day. Some are not as effected by daytime heat as others. Sunflowers are pretty strong and sturdy! They can handle being harvested in the middle of the day.
If you want your sunflowers to last as long as possible in the vase, it is best to cut them as soon as you see the first petals beginning to open on the bloom. Once cut, the sunflower will continue to open to its full bloom in the vase over time. Cutting sunflowers before they bloom fully is also a great way to make sure that the bugs do not eat all of the petals!
Cut the stalk to the length that you want, usually a bit longer than you think that you need, at a 45° angle. Snip off any leaves on the stem that would go under water. As soon as possible, place the stem into room temperature water and then arrange as you like!
my favorite sunflower varieties:
When it comes to growing sunflowers, I am a big fan of variety! They are one of my favorite flowers, and the smell of freshly cut sunflower stalks just brings me back to my first years of learning to be a farmer. I have tried growing just about every type of sunflower on the market as a retired flower farmer, and these are my favorite varieties to grow for cut bouquets and for just enjoying out in the garden:
ProCut® Series. The ProCut® Series is by Johnny’s Select Seeds, and it’s absolutely wonderful! Each sunflower has a nearly perfect uniform size and shape, and they have my absolute favorite sunflower: ProCut® Gold Lite DMR. The center is just as yellow as the petals!
Sunrich Series. This series is another with really beautiful uniform flower heads and excellent quality for life in a vase! They also have some unique colored centers, like the Sunrich Gold sunflower.
Double Blooms. If you enjoy some unique and funky-looking sunflowers, you should try planting some double blooming flowers! I love Double Quick Orange and Starburst Greenburst.
Autumn Colors. There are several beautiful autumnal colored sunflowers that come in deep reds, oranges, and even black. Try Shock-O-Lat or Desert Sun.
final thoughts:
Whether you are new to growing sunflowers or old, I hope that this guide helped you to learn how to grow your best crop of bright, happy sunnies! Sunflowers are a summer and autumn staple, at least in my book. These gorgeous sunflowers are so easy to grow and look beautiful in a vase on your table!
xoxo Kayla
