Can You Start Sunflower Seeds Indoors? (Yep, It’s Easy)

sunflower seedling in tray

Starting sunflower seeds indoors can be a fun and rewarding project, whether you’re doing it for the first time or are a seasoned pro. There are a few key steps to include in the process to help your sunflowers genuinely thrive.

You can start sunflowers indoors just as you would any other garden crop. A packet of seeds and a simple light setup will get you going. Plant to transplant out the seedlings after four weeks of growth indoors, and be sure to set a target planting date for after the last spring frost to ensure their survival.

In this article, you’ll get some tips on getting started and ensuring that your sunflowers make it to full bloom, plus a few ideas on how to stagger your sowings for months of flowers.

Can you start sunflowers indoors?

Starting sunflowers indoors is possible and generally relatively easy. All you need are a seed packet, grow lights, seed-starting mix, and seedling pots or another type of container. The seeds will sprout in less than a week, and within four weeks, they’ll be ready to plant in the garden.

As long as you transplant the sunflower seedlings when they are still small, they will adapt to their new environment and take off with quick growth.

What are the benefits of starting sunflower seeds indoors?

Starting sunflowers indoors does have a few benefits.

  • You can get a jump on the growing season, which is especially helpful if you live in a climate with a short growing season.
  • Sunflowers started indoors will also be less likely to fall prey to birds or squirrels who dig up the seeds.
  • You’ll have more control over the environment, so you don’t have to worry about spring rainstorms washing away your seeds or causing them to rot before they get a chance to germinate.

There are a few things to remember when starting any seed indoors. Indoor sowing requires more effort than direct sowing, and there is always the potential for problems like damping off. In addition, you’ll need to take care when transplanting the seedlings so as not to damage their delicate roots.

If you don’t have the space or inclination to sow sunflowers indoors, don’t worry! Direct sowing is almost always successful, as long as pests don’t get to your seeds. Just make sure to sow into warm soil, and you’ll have sunflower seedlings popping up in the garden in no time.

Six steps to starting sunflowers indoors

Here are the basic steps for starting sunflowers indoors:

1. Choose a warm spot in your home where you can set up a grow light and seed tray or small nursery pots.

2. Fill your containers with seed-starting mix and plant the seeds 1/2 inch deep.

3. Water the trays gently and keep the soil moist but not wet. If you are trying to germinate your sunflowers as quickly as possible, a heat mat set to 70 degrees Fahrenheit will speed up the process. 

4. Once the seedlings emerge, thin them out so that each has its own space, especially if there is more than one seed per tray cell.

5. Transplant the seedlings into the garden after all threat of frost has passed.

6. Don’t forget to harden the seedlings off in a sheltered spot to acclimate them to the outside temperatures and sun.

Test seed viability with a wet paper towel

If you have old seeds or you’re experimenting with bird seed (more on that in a moment), you can try the paper towel method to test your sunflower seed germination rate before planting them. 

To do this, place several seeds on a moistened paper towel, fold it over, and set it in a warm spot. Check the progress of the seeds every few days. If they’ve sprouted, plant them immediately. If not, try again with new seeds.

For a more in-depth guide to starting most flower seeds, bookmark this resource: Step-By-Step Guide To Starting Seeds Indoors (Plus a sample setup).

When should you start sunflower seeds indoors?

The best time to start sunflower seeds indoors is about four weeks before the last frost date in your area. This timing will give the seedlings a head start on the growing season without starting them too early, where they’ll get too large before it’s time to plant them outside.

You can plant sunflower seeds multiple times to stagger the blooming season. A neat tip from flower farmer Lisa Mason Ziegler is to start a new batch every two weeks for a continuous display of flowers from early summer until fall.

As the earlier plantings start to fade, the later sowings will just be coming into flower. This is especially critical if you’re growing sunflowers for cut flowers and want to avoid any gaps in your flower production.

If your gardening season is already underway and you want to squeeze in a crop of sunflowers before it’s too late, check out this article to see if you still have time: How Late Can You Plant Sunflowers? Check Your Zone & Date Here.

Hardening off sunflowers you started indoors

The final tip for successful seed starting is to make time to harden off your seedlings before transplanting them out to the garden. Hardening off is the process of acclimating young plants to the conditions they will encounter in their permanent home.

This means giving the sunflower seedlings time to adjust to being outside in the elements, including wind, rain, and direct sunlight. Start by placing them outdoors in a sheltered spot for a few hours each day, gradually increasing the time they spend outside until they can stay out all day long.

Make sure to keep an eye on the weather and bring them back inside if there is a danger of frost or extreme heat. Once they’ve been hardened off, your sunflowers will be ready to plant in the garden and start blooming!

For a complete guide to hardening off seedlings, bookmark this article: 7 Ways To Minimize Transplant Shock In Seedlings.

Learn more about sunflowers

Sowing sunflower seeds indoors is a great way to get a jump on the growing season, plan for continuous flowers, and ensure that your seeds don’t get eaten by pests. Make sure to harden off your seedlings before transplanting them into the garden for a beautiful display of blooms all summer long!

Here are some articles to help you along the way:

What Is The Best Soil Type For Sunflowers? (Tips For Healthy Plants)

Sunflowers Make The Best Companion Plant (17 Suggested Friends)

The Best Sunflowers For Cutting (Grown By Flower Farmers)

FAQ

Can I grow sunflowers from bird seed?

You can grow sunflowers from bird seed, but it’s best to purchase sunflower varieties specifically for planting in the garden. Bird seed is often a mix of sunflowers, millet, corn, and even peanuts, so you’ll need to pick out the sunflowers seeds to plant them.

Can I grow sunflowers from edible seeds?

If you purchase and sow whole, raw sunflower seeds with the shell on from the grocery store, you can often get those to sprout. The variety will be unknown, but chances are they’ll grow into a large, single-stem variety.

Can I grow sunflowers from roasted seeds?

Roasted sunflower seeds will not grow. The heat from the roasting process kills the embryo inside the seed that is necessary for germination. Roasted sunflowers seeds are best enjoyed as a snack!

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