How to Plant Sunflowers

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Sunflowers are a perfect choice. They grow in a variety of sizes and colors. They’re also easy to grow for gardeners of any skill level.

In this post, I’ll go over how to plant sunflowers. Keep reading to learn all about starting sunflower seeds!

Why Plant Sunflowers

Sunflowers are one of the easiest annual flowers to grow. They have high germination rates and mature quickly.

Pollinators love sunflowers, so they’re a good addition to any vegetable garden. Plant them as a border flower in your garden to help bees and beneficial insects pollinate your vegetables.

One of the best parts about starting sunflower seeds is being able to use them as beautiful cut flowers.

Sunflowers are upright, long-lasting, and add bright summer color to any arrangement. They pair perfectly in a vase with zinnias, cosmos, and celosia.

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Best Sunflower Varieties to Plant

Along with how to plant sunflowers, you may be wondering which variety to plant. This is a great question because, surprisingly, sunflowers aren’t one-size-fits-all.

Sunflowers are grouped by whether they produce a single-stem bloom or multiple branches of blooms.

You can also find sunflowers that are pollen-less or sunflowers that produce pollen.

Single-stem v. Multi-Branching

Single-stem sunflowers will only produce one flower, but they produce large, ideal blooms for cut flower arrangements. Grow these in succession by starting sunflower seeds every two to three weeks.

The best varieties of single-stem sunflowers – no doubt – belong to the ProCut Series.

Try classic ProCut Lemon, neutral ProCut White Nite, or colorful ProCut Plum.

Multi-branching sunflowers offer lots of small to large blooms on a single plant. These are great for gardeners who enjoy an extended harvest of sunflowers without succession planting.

Try multi-branching varieties such as Chocolate Cherry or Skyscraper.

Pollen-less v. Pollen Sunflowers

Pollen-less sunflowers are bred to be cut flowers. After a few days in a vase, you won’t find a pile of messy yellow pollen on your table. This is why they’re a go-to for florists and flower farmers.

All ProCut varieties are pollen-less.

Other sunflowers will produce pollen, but they provide plenty of food for bees and pollinators. These are best to plant if you want to benefit the rest of your vegetable garden.

Titan and Mammoth are great pollen-producing varieties.

When to Plant Sunflowers

Sunflowers are warm-season flowers, so they grow best during summer.

Starting sunflower seeds is best done when the soil has reached 70 degrees.

Because sunflowers grow so fast, you can wait until after your last anticipated frost to sow seeds. If you want a head start, sunflowers can be started indoors three to four weeks before your last anticipated frost.

Sunflowers are a great flower to grow in succession, meaning you can plant seeds every two to three weeks. This will give you blooms going into the fall.

Your last succession of sunflowers should be sown about two months before the first anticipated frost. This is commonly in late summer, around August, but it could be sooner if you have a short growing season.

This will give the sunflowers enough time to mature and produce blooms before being stunted by frost.

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How to Start Sunflowers Indoors

Learning how to start sunflowers indoors can come in handy for flower farmers. You’ll have mature sunflowers before anyone else in the neighborhood.

What You’ll Need

Set yourself up for success by having the proper seed-starting equipment.

Here are the main products I recommend for starting sunflower seeds indoors:

And don’t forget to load up on sunflower seeds! Hoss Tools has a great selection of all varieties of sunflowers. You can also check out True Leaf Market for more sunflower options.

Starting Sunflower Seeds

Starting Sunflower Seeds

Before starting sunflower seeds, you’ll need to fill your seed starting trays with seed starting mix.

The mix should be flush with the top of the tray, even when moist. This is a good indication of no air pockets, which can dehydrate a seedling.

Using a pencil or wood label, create an indention in the mix. Sunflowers should be planted at a depth of 1/2″.

Place the seed into the indention and lightly cover it with soil. Because sunflower seeds are large and have high germination rates, it’s fine to only sow one seed per cell.

Once your seeds have been sown and labeled, place them on a heat germination mat under a full-spectrum grow light. This will help warm the soil and speed up germination.

The seeds should germinate in four to 14 days, depending on soil temperature.

Transplanting Sunflowers

After your last anticipated frost, you can begin to harden off your sunflower seedlings. To do this, leave the seedlings out for increasing intervals of time every day.

After a week or two, the seedlings should be ready to transition to the garden.

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How to Plant Sunflowers Outdoors

To direct sow sunflower seeds, place seeds 1/2″ deep every six to 24 inches. Allow more space for larger or multi-branching varieties.

The closer your seedlings are, the smaller your sunflower blooms will be. Just be careful with planting too close together. This can decrease airflow around the flowers, inviting different diseases.

Rows should be spaced two to three feet apart. This will allow you room to come in and cut blooms for arrangements.

Thinning Out

To be on the safe side, you can always sow more sunflower seeds, then go back through and thin them out.

To do this, place a seed every three inches. Once the seedlings are two to three inches tall, thin them to every six to 24 inches. Always choose the strongest, healthiest seedling to let grow.

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Caring for Sunflowers

Water

Sunflowers have similar water needs to other warm-season vegetables. The soil should be consistently moist. This is helped by watering the sunflowers deeply every three to seven days.

Water needs are affected by temperature and rain. Always assess the top layer of soil for dryness before watering.

Once established, sunflowers do well in the heat and can often be drought-tolerant.

Fertilizer

Sunflowers’ fertilizer needs can be based on the health of your soil. If you’re growing sunflowers in rich soil filled with organic matter, your sunflowers will likely grow healthy and strong.

If you add too much fertilizer on top of good soil, the sunflowers may develop more foliage than blooms. This is a common result of too much nitrogen.

But if you suspect your sunflowers need an added boost, a slow-release fertilizer works great. These fertilizers will slowly feed plants without overwhelming them.

Common Pests and Diseases

Let’s talk about the not-so-fun part of starting sunflower seeds – pests and diseases. Sunflowers are less prone to diseases and pests than other garden plants, but it can happen.

Downy mildew is one of the most common diseases you’ll see with sunflowers. Downy mildew is a fungus that causes foliage to turn white and wither.

It’s caused by cool, wet soil that doesn’t drain well and is encouraged by high humidity. Allow sufficient air circulation between sunflowers to avoid this disease.

One of the most common sunflower pests to look out for is the sunflower moth. They appear in early summer when sunflowers are starting to bloom.

These small, silverish-gray moths will lay eggs, which feed on the head of the sunflower. This causes damaged, unsightly blooms.

To avoid these pests, stagger sunflower planting times. You can also apply an insect spray to the affected plants.

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How to Harvest Sunflowers

Every gardener looks forward to this stage of starting sunflower seeds – harvesting! Depending on the variety, sunflowers typically mature within 60 to 120 days.

A mature sunflower bloom will begin to show small sneak peeks of the flower petals.

Sunflowers should be harvested just as the bloom head begins to open. The sunflower will finish opening after being cut. This gives you the longest vase life in a harvested sunflower.

Cut the sunflower stem about two feet down from the bloom, depending on how long you want your stem to be.

Allow the harvested sunflowers to sit alone in a bucket of cool water for a few hours. This lets your sunflowers rest before being arranged with other flowers.

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How to Harvest Sunflower Seeds

You can also harvest sunflower seeds. Once the petals begin to fall off, tie a mesh bag or cheesecloth around the bloom head. As the head dries, the bag will catch any seeds that fall.

You should be able to loosen the seeds from the head once it dries completely. To speed up the drying process, cut the sunflower stem and hang it upside down in your greenhouse or garden shed.

Our blog post, How to Roast Sunflower Seeds, will go in-depth on everything to know about enjoying your sunflower seed bounty.

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Wrapping Up How to Plant Sunflowers

Learning how to plant sunflowers is a fun, easy way to add flowers to your garden! There are so many different varieties, each one having its own purpose and aesthetic. Give these garden favorites a go this season.

Do you want to learn more about seed starting? Visit the Seed Starting page on our website for more on how to start vegetables and flowers indoors.

Want to discover more about these beautiful flowers? Then keep reading about sunflowers to learn how to plant and grow them, as well as dry them for décor, and even make sunflower oil!