Sunflower seeds can be planted outdoors in garden soil or containers after the last spring frost. Sunflowers prefer well-drained soil and a full sun planting location but tolerate less-than-perfect conditions.
Plant each seed about ½”-1″ deep and cover the seeds lightly with garden soil. Sunflower seeds are generally spaced about 12″ – 24″ apart. Water the garden area after planting the seeds.
When to plant sunflower seeds
Sunflower seeds are generally planted in the spring after the last frost. Most gardeners use their local average last frost date as a guideline and then watch the weather forecast each spring for nighttime temperatures that remain above freezing. Sunflower seedlings are relatively tough and can survive light frosts, especially if covered overnight.
Sunflowers are usually planted from March to May. While local climates differ, most gardeners in southern areas with mild winters generally plant sunflower seeds in March-April. Gardeners in cooler climates with freezing winters generally plant sunflower seeds in April-May. Sunflower seeds can also be planted every 2-3 weeks throughout spring and early summer for a longer flowering period in the fall. Many sunflower varieties take only 2-3 months to grow from seed to flower, meaning you can plant sunflower seeds as late as July in many climates.
While sunflowers grow best when the seeds are planted outdoors in their intended growing location, seedlings can also be planted indoors in early spring. This usually results in the first sunflowers blooming a few weeks before direct-sown sunflowers bloom. Indoor-grown sunflower seedlings are usually planted from seed 2-4 weeks before the average local last frost date. The seedlings can then be transplanted outdoors once the danger of frost has passed.
Where to plant sunflower seeds
Sunflowers grow best in full sun planting locations that get at least 6-8 hours of direct sunlight each day. While they will grow in shadier spots, the plants will likely be spindly and the flowers quite small. They should also be planted in a spot where they can be watered easily as young plants. In windy climates, they may need to be staked (especially taller varieties). While they grow best in well-drained sandy loam soil, they are tolerant of heavy clay soil.
Sunflowers can also be planted nearby or in your vegetable garden as a beneficial companion plant. Sunflowers are one of the most reliable companion plants for crops that depend on insect pollination, as these bright blooms attract all sorts of pollinators and beneficial insects.
How to plant sunflower seeds
Sunflower seeds are easy to plant outside in the garden. Here are the basic steps for planting sunflower seeds:
- Clear the soil of any plant debris and rake the soil surface flat. You may also wish to apply a 1″-thick layer of organic compost to the garden soil and/or mix in a slow-release organic fertilizer.
- Make a small planting hole for the first seed. Sunflower seeds should be planted between ½”-1″ deep. Most seeds are planted a half-inch deep. Only varieties with very large seeds (like Mammoth) need to be planted a bit deeper if your soil dries out quickly.
- Make planting holes for the rest of the seeds to be sown. Sunflower plants are usually spaced between 12″-24″ apart. If you have quite a few seeds to spare, the seeds can be sown as close as 2″ apart as long as the young sprouted plants are thinned out to 12″-24″.
- Place a seed in each planting hole. Again, if you have extra seeds, you can put 2 seeds in a single hole as long as you thin out the weaker seedling once they have sprouted.
- Cover each seed with ½”-1″ of soil. Use the soil that came out of the planting hole. Gently pat the soil down. You can give the soil a gentle rake with a handheld cultivator.
- Water the planting area thoroughly after planting. Check to make sure the water is draining nicely into the soil rather than ponding on the surface.
How to plant sunflower seeds in pots
Smaller varieties of sunflowers can be grown in pots or larger planters. Most of the instructions are the same as for planting seeds directly in the outdoor garden soil, as described above. The seeds should be planted a ½” deep in the potting soil in the pot. And as with in-ground gardens, be sure to water the soil thoroughly after planting and check that water can drain out of the bottom of the pot.
When growing sunflowers in pots, be sure to use a pot that drains out excess water easily with an adequate drainage hole. You’ll also want to fill the planter with high-quality organic potting mix and position it in a sunny location on the patio. Lastly, sunflowers grown in pots generally need to be watered much more frequently than sunflowers grown in the ground as the planters tend to dry out quickly.
While you could likely grow any kind of sunflower in a container as long as the container was large enough (like a whiskey barrel garden), there are some dwarf sunflower varieties that are perfect for growing in a patio planter or flower pot, including:
- Teddy Bear Sunflower
- Hella Sonnenblume Sunflower
- Suntastic Sunflower
- Suntastic Pink Bicolor Sunflower
How to plant sunflower seeds indoors
There are three common reasons for planting sunflower seeds indoors:
- To grow a dwarf sunflower in a flower pot;
- To grow a tray of sunflower microgreens;
- To grow small seedling plants for later transplanting outdoors.
For dwarf sunflowers grown in flower pots, start by choosing a short variety (such as the dwarf varieties listed in the previous section). Sunflower microgreens are most commonly planted from Black Oil Sunflower seeds. Seedling plants can be planted from whichever varieties you’d like to plant outdoors after the last frost.
Sunflowers grown indoors grow best when planted in high-quality organic potting mix. The seeds should be kept moist until germination and watered regularly afterwards. Once the seeds have sprouted, place the tiny seedlings under a bright plant light to allow for ample photosynthesis. Air circulation is also helpful for the young seedlings.
Choosing which kind of sunflower seeds to plant
There are endless varieties of sunflower available for planting. There are giant sunflowers that tower over the garden, sunflowers that branch and grow multiple flowers, specialty florist ornamental sunflowers, and tiny little dwarf sunflower varieties. Here are 5 of the best sunflower varieties to consider when you’re shopping for sunflower seeds.
1. Mammoth sunflower
The Mammoth sunflower is the classic giant sunflower variety. This heirloom was developed in Eastern Europe and is known for its large sunflower heads and high-quality sunflower seeds.
2. Lemon Queen sunflower
The Lemon Queen sunflower is the most popular sunflower for attracting beneficial pollinators to your garden. These lemon-yellow flowers are well-known favorites of bees and other beneficial insects due to their high-quality nectar.
3. Black Oil sunflower
The Black Oil sunflower is the traditional variety planted to attract birds to your yard due to the oil-rich seeds they produce. These seeds are generally packaged in large sunflower seed bags for filling bird feeders and can generally be purchased at garden centers and big-box stores. While you can certainly plant the seeds that are sold as bird food, most gardeners grow more uniform plants from seeds selected specifically for planting:
4. Teddy Bear sunflower
The Teddy Bear sunflower is a short heirloom sunflower with masses of very thin petals giving it a fluffy appearance. These puffball-type sunflowers grow to reach only 3′ high, making them a favorite in children’s gardens.
5. ProCut sunflowers
The ProCut sunflower brand is a line of specialty sunflower varieties grown mainly in cutting gardens to make floral bouquets. ProCut Sunflowers are available in a wide range of different shades.
How to grow sunflowers
Sunflowers are relatively easy to care for once the seeds have sprouted. The plants should be watered regularly while they are young, but become more drought tolerant once the plants reach several feet tall. That said, irrigating the plants generally leads to a more reliable crop of sunflowers. As with water, these plants also need ample sunlight daily to truly thrive. If your soil is nutrient-poor, you may also wish to apply a slow-release organic fertilizer at the frequency recommended on the product you choose.
Sunflower season
Sunflower season generally occurs in August to September. These two months are generally the peak of the sunflower harvest season, making this time popular for sunflower festivals and cheerful bouquets at the farmer’s market. Different varieties of sunflowers bloom at different periods, from late summer to early fall. Seedlings planted early in the spring may bloom in July in mild climates. Some farmers sow seeds every two weeks during spring and sometimes into early summer, making fresh sunflowers available in mild locations into October.
Sunflowers take between 60-110 days to grow, depending on the variety of sunflowers and local growing conditions. Dwarf Teddy Bear sunflowers take about 60 days to bloom in good conditions after the seeds are planted, while tiny Suntastic sunflowers take only 65 days to bloom. Larger 6′-tall florist sunflowers take more than 100 days to mature after being planted. Giant sunflowers like Mammoth and Titan take 110+ days to reach maturity.
