When To Plant Sunflowers

When To Plant Sunflowers

Last Updated On: April 19, 2022

Sunflowers are an iconic staple grown worldwide for their beauty and edible properties. A row of tall sunflowers is magnificent, and really adds a lot of visual appeal to a garden or, when grown indoors, a room. With summer quickly approaching, we thought it would be a good idea to answer the common question of when to plant sunflowers, and general tips for starting your crop off on the right foot.

This article will look in-depth at timing your sunflower planting correctly for optimal results. If you’re interested in our general overview of growing sunflowers indoors (and out), you can check that guide out here.

When To Plant Sunflowers Outdoors

When growing outdoors, the ideal planting time is early to mid spring. This depends on your local environment, in particular when your last frost date occurs.

Usually, you want to plant about 2-3 weeks after the last frost date has passed. This is also when the soil begins to warm up, which is important as sunflower seeds germinate in warm soil.

When planting, you can sow the seeds directly into the soil. Start by choosing a sunny location that gets 8 or more hours of sunlight per day. Plant them about 1” deep and space them about 8” or so apart. You can always thin the seedlings out later if this ends up being too crowded.

A quick note, when growing sunflowers outdoors, it’s usually wise to plant more than you think you’ll need. This is because sunflowers are a prime snack for a variety of critters from squirrels, to rabbits, and even deer. By planting more at the start you can offset some of your losses that will inevitably happen.

When To Plant Sunflowers Indoors

If growing indoors you have a lot more freedom on when you can start. Depending on whether you’re growing indoors permanently or moving outside will have some effect on your specific timing.

If you’re growing your sunflowers exclusively indoors then you can start them at almost any time. While it will likely be easier in summer due to the sun, it’s perfectly doable to start them in fall or even winter. In these cases, you will likely need to utilize a grow light to get your plants enough light.

If you intend to move them outdoors the best time to plant is right around your last frost date, or about 2-3 weeks before you’d sow them outdoors. This gives your plants a few weeks to grow indoors before transplanting outdoors. The timing here works well as a sunflower is ready to transplant at about the 2-3 week mark. By starting indoors, you get a few weeks head start over solely outdoors. This means you’ll have larger, fuller plants that are ready to harvest sooner than those that started their seeds outdoors.

Tips For Starting In Soil

Timing is important when starting outdoors as a late frost will damage or kill your plant. Your seeds also won’t germinate if the soil isn’t warm enough. For those reasons, you want to be sure that you’re fully into spring before you start planting or it’s likely your plant won’t grow.

As noted above, animals can be a potential problem when growing outdoors. Putting up some chicken wire, or similar fencing, can help protect your plants and seedlings. I also recommend planting a few more seeds than normal to help offset any losses.

Tips For Starting Indoors

You’ll almost certainly need a grow light if you’re starting your seeds indoors. Without one, you’re likely to get leggy and weak growth. Sunflowers need a lot of light to grow, especially in their early stages, and most homes simply won’t get enough light.

If you’re moving your plants outdoors you’ll also want to spend about 1-2 weeks acclimating them to their new environment. This involves moving them outdoors, starting in the shade for a few hours and gradually increasing both of these. This helps your plant get accustomed to the new environment, and prevents shocking the plant or exposing it to environmental factors like wind before it’s strong enough to handle them.

Basic Sunflower Care

Whether you’re growing indoors or out, the care for sunflowers is relatively similar. Sunflowers are generally pretty easy and hardy plants to grow, with a little basic care you shouldn’t have much trouble with them.


Sunlight is the biggest issue gardeners will face when growing sunflowers, especially indoors. Look to get at least 8+ hours of bright sunlight per day; they are called sunflowers after all.

Indoors, you’ll likely need a grow light to hit these amounts and to provide the intensity needed. Outdoors, make sure you choose a spot that is in direct light and remains so most of the day.


Sunflowers don’t need a lot of water, and you’ll generally need to make sure they get a decent amount 1-2 times per week. You want the soil to remain a little moist, but not constantly soaked. You can also mist the plants between waterings to keep them moist without risking overwatering.

The only exception to this is sunflower seedlings. When they’re young, sunflowers need more water. During the seedling stage look to water about 3-4 times per week.


Most sunflowers are annuals, they die back each year and will need to be replanted. There are some varieties that are perennials, so make sure that you pick the variety that you want.

Either type can add beauty to your garden, and care is very similar between the two. There are a few differences between the varieties though, many perennials only bloom in their second year for example. Do a little research on your chosen variety so you know what to expect and to ensure it matches up with your gardening goals.

Common Sunflower Issues

My Seeds Never Germinate

Often a case of being planted too soon, or in overly wet soil. Sunflowers will only germinate in warm soil after the last frost date has passed by a few weeks. Planting too soon means the seeds likely won’t get warm enough to properly germinate.

My Sunflowers Look Weak and Leggy

Not enough light is usually the issue here. Make sure you plant them in a sunny spot that gets lots of direct sunlight, or supplement with a grow light set for 8+ hours per day. Note that sunflowers like direct sunlight. If you place them in in-direct or partially shaded light you will need to get more than the 8 hours.

My Sunflowers are Missing Leaves

This is often caused by critters like deer or rabbits using your plant as a quick snack. You can set up some fencing to keep them out, or use one of the products on the market that are marketed to repel these types of animals.

My Seeds Were Dug Up Before Germination

Similar to the above, although this is likely to be smaller animals like chipmunks or squirrels that are digging up your seeds. Add barriers or use products marketed to keep these critters out of your garden.

When To Plant Sunflowers

Armed with the above knowledge you’re ready to grow beautiful sunflowers this season. Getting the timing right is crucial to a successful crop, especially if you plant to grow them outdoors. Get that right, and add a healthy dose of light, and you’re well on your way to growing beautiful sunflowers.

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