Growing sunflowers in pots: A step-by-step guide

Cheerful and charming, sunflowers are one of the most popular – and easiest! – annual plants to grow. There are pint-sized sunflowers that grow just a foot tall and giant varieties that reach for the sky, but you don’t need a big garden to grow sunflowers. These classic summer bloomers can be planted in plastic pots, fabric planters, or even buckets. Keep reading to learn more about growing sunflowers in pots. 

Why grow sunflowers in pots

There are many reasons to grow sunflowers in pots, but perhaps the best reason is space. Sunflower plants can take up a lot of room in the garden, but there are many compact and container-friendly varieties available to plant in pots. Sunflowers not only brighten up a sunny deck, patio, or balcony, but the blooms also attract pollinators like bees and butterflies, and can be clipped for summer bouquets. Need more reasons to plant sunflowers in pots? They’re also an easy flower to grow and drought, insect, and disease-resistant.

Selecting containers for growing sunflowers in pots

Success growing sunflowers in pots starts with choosing the best containers. I have a rag-tag collection of plastic containers, fabric pots, and terra cotta planters in my garden shed and all can be used for growing sunflowers in pots. The two biggest considerations when selecting containers is size and drainage. Start by reading the seed packet description to see how large your chosen sunflower variety will grow. Is it a dwarf sunflower? Or a single stem tall variety? Is it a large, branching sunflower? By matching the mature size of the variety to the size of the pot you can be assured you’re providing enough space for healthy root growth. I generally plant sunflowers in 7 gallon to 10 gallon fabric pots or plastic containers that are at least 10 to 12 inches in diameter.

Or perhaps you want to grow several sunflowers in a single window box or planter. Again, look to the seed packet to learn the mature size of the sunflower variety so you can figure out how far apart to space each seed. To make it easier, I’ve got a handy seed spacing guide below.

The other consideration when selecting a container is drainage. Sunflowers need well-draining soil so a pot that has ample holes for water drainage is essential. If the pot doesn’t have any drainage holes, you’ll need to add some to the bottom or choose another pot. It’s easy to add drainage holes to a plastic pot, window box, or bucket using a drill and 1/2 inch drill bit.

The best soil for growing sunflowers in pots

Sunflowers grow best in a loose potting mix amended with organic matter like compost or aged manure. When growing sunflowers in pots I fill my containers with a blend that is roughly 50% good quality potting mix and 50% compost. I also add a slow-release organic flower fertilizer to the growing medium to ensure my sunflowers have plenty of nutrients to promote healthy growth and big flowers. 

The best site for growing sunflowers

Sunflowers, as the name suggests, are light-loving plants that need full sun to grow well. The best site for growing sunflowers in pots is one that provides at least 6 to 8 hours of direct light each day. If grown in less light you may find the stalks stretch and topple over as they reach for the sun. 

Types of sunflowers to plant in pots

Sunflowers can be categorized by their flower production or height and these characteristics can help you select the best types to grow in containers. You can buy sunflower seeds from seed catalogs or pick up packets from your favorite local nursery.

Sunflowers by flower production:

• Single stem sunflowers – Single stem varieties are often grown for cut flower production as they produce one high-quality bloom per stalk. These varieties are easy to grow in pots. For a non-stop display of color all summer long, succession plant single stem sunflowers every two weeks from late spring through early to mid-summer.
• Branching sunflowers – These varieties can also be grown in pots, but they do produce sizeable plants with continuous blooms. Once again, match the pot size to the mature size of the variety. Expect up to several dozen, often smaller, flowers per stalk. The individual stems of branching sunflowers aren’t as long as single stalk varieties, but they can be cut for bouquets or left in the garden for the bees and butterflies. 

Sunflowers by height:

• Dwarf sunflowers – Sunflowers that grow between 12 to 42 inches tall are classified as dwarf varieties. They make excellent pot plants alone or in combination with other sunflower varieties or annual flowers. 
• Tall sunflowers – The height of tall sunflowers varies, but varieties that grow taller than 42 inches are considered tall sunflowers.

When to plant sunflowers in pots

Sunflowers are heat loving plants and direct seeded once the last frost has passed in spring. You can get a head start on the flowering season by sowing the seeds indoors under grow lights. Sow the seeds in 4 inch pots 2 to 3 weeks before the frost date, but don’t start them indoors too early. Pot-bound sunflower seedlings are sensitive to transplanting which can impact the mature plant and flower size. 

How to plant sunflowers in pots

When you’re ready to plant your pots, fill them with the growing medium and grab your seed packets. If you want a head-start on the blooming season, you’ll find seedlings of container-friendly varieties like Sunfinity at local nurseries.

Keep in mind that the mature height of the flower stalk and the mature size of the flower head are dependant on plant spacing. If you crowd sunflowers in their containers you’ll end up with shorter plants and smaller flowers. Give them space to grow if you want full-sized plants and blooms. To direct sow, plant sunflower seeds a 1/2 inch deep. To learn how far apart to plant sunflowers, check out my handy spacing guide below:

• Single stem tall sunflowers – Space plants 8 inches apart, or grow one plant in a 3 gallon pot, or three plants in a 10 gallon pot.
• Single stem dwarf sunflowers – Space plants 6 inches apart, or grow one plant in a 1 gallon pot, or three plants in a 5 gallon pot. 
• Branching tall sunflowers – Space plants 18 to 24 inches apart or grow one plant in a 7 to 10 gallon pot.
• Branching dwarf sunflowers – Space plants 12 to 18 inches apart, or grow one plant in 3 gallon pot, or 3 plants in a 7 gallon pot.
• Giant sunflowers – Space plants 18 to 24 inches apart or grow one plant in a 10 to 15 gallon pot.

Growing sunflowers in pots

Once the seeds sprout, sunflowers need regular water to help them form sturdy stalks and large flowers. You’ll have to water sunflowers planted in pots more often than those grown in garden beds. This is because pots dry out quicker. Watering frequency depends on the weather as well as plant and pot size. I check soil moisture by sticking my index finger into the growing medium. If it’s dry an inch down I’ll water. 

Sunflowers aren’t plagued by many pests but it’s a good idea to watch for insects like aphids which can cluster on the growing tips of the plants or beneath the leaves. If you spot any aphids, knock them off the plant with a jet of water from your hose. Slugs and snails also enjoy sunflower seedlings. Handpick and dispose of these slimy creatures. I’ve also had wildlife like squirrels and chipmunks feast on the seeds of my late summer sunflowers, but I don’t mind. In fact, it’s one of the reasons I grow them! It’s fun to watch the antics of these critters as they gobble up the seed heads and leap from stalk to stalk. 

Growing giant sunflowers in pots

Can you grow giant sunflowers in pots? Yes! The keys to success are variety selection and pot size. First, choose a variety like Giganteus, Mammoth, or American Giant, whose plants can grow up to 16 feet tall and produce 10 to 12 inch diameter flowers. Next get a big pot, ideally one that holds 10 to 15 gallons of soil. Fill it with a blend of half compost and half potting mix and add a slow release organic flower fertilizer. Direct seed or transplant a giant sunflower seedling after the risk of frost has passed in late spring. Water consistently throughout the growing season to ensure the plant has ample moisture.

The best sunflowers to grow in pots

Classic sunflowers have golden-orange petals and large chocolate centers. And while these remain extremely popular, seed catalogs offer many different varieties of sunflower seeds to grow. Have fun with the diversity of flower sizes and colors. Below are some of my favorite sunflowers to grow in pots, but again, any varieties can be planted in containers if you choose the right planter. 

Dwarf Double Sungold sunflower

Shake up your deck or patio pots with Dwarf Double Sungold, a sunflower that grows just 2 to 3 feet tall. Each flower is fully doubled and packed with petals. The plants may be on the small side, but they produce a dozen or more fluffy flowers which make long-lived bouquets. 

Sunfinity sunflower

Sunfinity has been called “the next generation of sunflower” due to its  extended blooming period that lasts for much of the summer. It’s definitely a knockout in a pot! The plants grow up to 4 feet tall and 2 feet wide and can produce 50 flowers per plant. Each bloom is 3 to 4 inches in diameter. This hybrid variety is available from select seed companies as well as at local garden centres, but expect to pay several dollars per seed. 

SunBuzz sunflower

SunBuzz is a standout in pots and planters. It grows up to 20 inches tall with 4 inch diameter flowers that have bright yellow petals and deep brown centers. It’s quick to bloom and pumps out fresh flowers all summer long. To grow one SunBuzz sunflower in a pot, select a container that is at least 8 to 10 inches in diameter. If planting multiple seeds in a larger container, space them 6 to 7 inches apart. 

Solsation Flame sunflower

This ultra compact sunflower was bred for growing in pots. It has a bush-habit and grows just 18 inches tall, but produces its eye-catching two-toned flowers from mid-summer until first frost. Each bloom has bronze red petals tipped in gold and dark brown centers.

Suntastic sunflower

Suntastic is an All-America Selections winning dwarf sunflower with plants that grow a tidy one-foot tall. They’re super early to flower and perfect for pots, planters, and window boxes. The flowers reach 5 to 6 inches across and have sunny yellow petals and brown centers. This is a great sunflower for kids who can watch their potted plant go from seed to flower in just 65 days.  

Firecracker sunflower

I love the brilliant two-tone flowers of Firecracker, a branching sunflower that grows 36 to 42 inches tall. Each plant yields armfuls of the 4 to 5 inch diameter red and gold flowers. The compact, dense growth makes this a great choice for containers, but it’s also the perfect variety for a cutting garden. Why? It’s because each flower has a 16 to 24 inch long stem. Harvest the stems as each flower bud begins to open.

For further reading on growing sunflowers and other annual flowers, be sure to check out these articles:

• When to plant sunflowers: 3 easy options
• Growing marigolds from seeds
• How to grow Salpiglossis: the painted tongue flower
• Learn how to grow zinnia profusion

Are you planning on growing sunflowers in pots?