DIY Flower Care Flower Facts

How to Grow Sunflowers

Sunflower garden surrounded by blue flowers

Sunflowers are some of the most cheerful flowers out there, whether you’re growing them in your garden or enjoying them as sunflower bouquets. Since 2021 is the Year of the Sunflower, it’s the perfect time to start growing sunflowers at home. To help you out, we’re going to cover basic growing information including when to plant sunflowers, how to water and fertilize them, and how to harvest flowers for seeds or bouquets.

Flower Profile

Scientific name: Helianthus annuus
Native range: Present-day North America
Height: 3-30’ depending on the variety
Light requirements: 6+ hours of bright light each day
Soil: Well-aerated and well-drained with a pH between 6.0 and 7.5
When to plant: March through July

2021: Year of the Sunflower

The sunflower is here to brighten up 2021! As more and more people explore growing plants, the National Garden Bureau has declared 2021 the Year of the Sunflower. Sunflowers are easy to grow flowers, so they’re perfect for beginner gardeners.

Sunflowers are annuals, which means they bloom for one year. While this may seem like a negative, it means you get to experience the joy of planting seeds and watching sunflowers grow each year. Plus, sunflowers offer beauty as well as edible seeds.

These flowers also hold importance to Native Americans, Greeks, and more. The most common sunflower meaning relates to happiness and good luck.

When and Where to Plant Sunflowers

Closeup of sunflowers in the garden

What Time of Year to Plant

While sunflowers resemble mini suns, they don’t produce the heat necessary to ward off cold temperatures. Since they cannot handle frost, you should wait to plant sunflowers until the danger of frost has passed. Depending on your location, this can be anywhere from March to June.

Once frosts are out of the question, you can plant your sunflowers. Sow seeds every two to three weeks for a continual harvest until the first fall frost.

If you’re starting seeds indoors and then transplanting seedlings outside, you can start seeds a few weeks before the last frost date.

Choosing a Location

As we mentioned above, sunflowers need at least six hours of bright sun each day. However, they prefer 8-12 hours of full sun. Therefore, make sure your location receives plenty of sunshine.

Another thing to consider is that sunflowers can really grow! Many varieties can grow over six feet tall, so they really make a statement.

You also want to take a look at the soil and drainage. Sunflowers prefer well-drained soil. If you notice an area is always wet, avoid planting sunflowers there. If you have soil that is extremely compacted or high in clay, you can add in organic matter such as compost. This will improve soil texture and allow the soil to hold more water in times of drought.

Spacing

While you may be tempted to pack lots of plants into a small space, you should properly space your sunflowers. The precise spacing will depend on the variety of sunflower you’re growing.

In general, there are two types of sunflowers: single-bloom and branching. Single-bloom varieties grow straight up and produce one flower atop their stalk. Therefore, you only need to space them 6-8 inches apart. Branching sunflowers produce multiple flowers on multiple stalks. Since they require a bit more room, space them at least two feet apart.

If you’re unsure about how far apart you show space your plants, consult the seed packet. Seed companies should include growing information including how deep to plant the seeds and far apart to space your plants.

If you’re worried that all your seeds might not germinate, you can always plant many seeds close together and later thin seedlings. For example, you can plant a seed every four inches and later thin the seedlings so they’re eight inches apart.

Staking

Even when sunflowers grow over seven or eight feet tall, they’re often fine without a stake. Their strong root system holds them in place and keeps them from toppling over.

With that said, you should stake your sunflower if you see it start to sway and fall. Varieties with extra-large flower heads are prone to arching downwards. To stake a sunflower, pound a four to six-foot metal or wooden stake into the ground a few inches away from your flower’s stalk. Make sure at least eight inches of the stake is underground. Next, use a string to tie the stalk to the stake.

Growing Sunflowers

Sunflower seedlings sprouting

Watering

Besides being beautiful, sunflowers are also quite hardy. Once the plants become established, they can withstand periods of moderate drought. With that said, regular watering will produce the healthiest plants. Water your plants every 2-3 days if it doesn’t rain. When you water, thoroughly soak the soil to encourage the plants to develop deep roots.

While mature plants can handle periods of drought, you will need to water seeds and seedlings more often. Make sure to keep the soil moist until seeds germinate. You should also water seedlings every day until they become at least six inches tall.

Fertilizing

Sunflowers are heavy feeders; in other words, they use a lot of nutrients! Therefore, it’s a good idea to add plant fertilizer to give your sunflowers a boost. Look for a granular fertilizer designed for outdoor flowers and apply it after the plants have developed their first set of true leaves.

Avoid applying too much nitrogen, as this can lead to robust plants but no blooms.

Pruning

Sunflower plants don’t require much pruning or trimming. If you notice yellow or brown leaves, you can remove them using your hands. Make sure to wear gloves, as the leaves and stalks can irritate your skin.

If you’re growing a branching variety, you should remove flower heads after they’re done blooming. This will help the plant send energy to new buds so you can enjoy new flowers for weeks.

Mulching

Mulching the soil around your sunflowers provides a variety of benefits. It helps lock in water, so you don’t need to water as frequently. It also prevents weeds from germinating and competing with your flowers. You can use hardwood mulch, leaves, or straw to mulch your sunflowers

If you don’t want to mulch, you don’t need to. Your flowers will grow just fine, but you’ll need to water more frequently and keep an eye out for weeds.

Managing Pests and Disease

While it would be great if humans were the only ones who loved sunflowers, this isn’t the case. A number of pests love to snack on these plants, and sunflowers are also susceptible to several diseases. Keep an eye out for these common pests and diseases.

Cutworms

These ugly, squishy larvae love to feed on young sunflower seedlings as well as the leaves of older plants. While they can do serious damage, they’re often hard to spot since they’re most active at night.

If you notice your plants have been chewed by a critter, take a moment to dig around in mulch or weeds near the base of the plant. If you see a big brown or gray worm, squish it. If you don’t like the idea of finding and squishing these pests, you can apply diatomaceous earth near the base of your plant. While this material is harmless to humans and pets, it kills soft-bodied insects like cutworms.

Sunflower Bud Moths

While a moth might sound like a welcome guest in the garden, the larval form of these moths is not. The white worms tunnel into sunflower stems or flower buds and chow down. If they choose to attack unopened flower buds, they can prevent the development of the beautiful sunflowers you’ve been waiting for.

If you spot these pests, there isn’t a whole lot you can do besides remove them with your hands. The best solution is to remove any weeds and other plant debris where these larvae like to hide.

Downy Mildew

If you notice your plants are covered with a powdery, white substance, they are likely impacted by downy mildew. This fungus can quickly wipe out your plants.

Downy mildew occurs most frequently in wet conditions. If you live in a wet area, it’s worth looking into sunflower varieties that are resistant to downy mildew.

Growing Sunflowers for Bouquets

Bouquet of sunflowers displayed in a home

 

Cutting Sunflowers

After weeks of caring for your plants, the moment you’ve been waiting for has arrived: flowers! If you’d like to bring your flowers inside to enjoy, you want to cut them at just the right time.

One of the most important things to remember is that you shouldn’t wait until the flower heads fully open before you cut your flowers! For a long vase life, you should cut the flowers when the petals start to unfurl from the center of the flower head.

When you cut your sunflowers, make sure to use a clean and sharp knife or pair of pruning shears. Cut the stems at a 45º angle and immediately place the flowers in water. Bring the flowers out of the sun as soon as possible.

The time of day you harvest is also important. It’s best to cut sunflowers in the morning after the dew has dried but before it becomes hot. Alternatively, you can harvest in the evening once the air has cooled.

Creating Sunflower Arrangements

Some of the top tips on arranging sunflowers involve letting these big blooms shine! If you’re mixing them with other flowers, it’s best to add the sunflowers at the end. Don’t forget that closed buds will open into fuller blooms.

Since sunflower stems don’t have any leaves, you don’t need to worry about removing any foliage. However, the prickly stems can irritate some people’s skin, so you might want to wear gloves while arranging your flowers.

Harvesting Sunflower Seeds

mature sunflower plant ready for seeds to be harvested

When to Harvest Sunflower for Seeds

If you’re growing sunflowers for their delicious seeds, you’ll need to wait until the flowers develop seeds before harvesting. Leave the flowers on the plant until the petals dry. Once the petals are nice and brown, don’t wait to harvest, or critters might eat the seeds before you get a chance to. To harvest, cut the stem a few inches below the flower head.

Preserving Seeds

Once you’ve cut the flower from the stalk, place the head in a paper bag in a dry area for a few weeks. Make sure the area has good airflow, or the seeds may rot. Once the seeds are dry, remove them by running your hand over the flower head.

To help the seeds keep for as long as possible, dry them a bit more after you remove them. You can use a dehydrator or place them in a dry room with plenty of ventilation.

Once your seeds are dry, store them in an airtight container.

Cooking Ideas

While sunflower seeds are great snacks in their own right, they also lend themselves to creative uses in the kitchen. Try sprinkling them on salads, adding to bread dough, or mixing them with your favorite spices and then roasting them in the oven.

Some of Our Favorite Sunflower Varieties

Close up of Teddy Bear Sunflowers

Mammoth Russian

If you’re growing sunflowers for edible seeds, Mammoth Russian is a great choice. Plants grow up to 12 feet tall and produce big seed heads with large, delicious seeds.

Autumn Beauty

While you may think sunflowers always have yellow petals, Autumn Beauty shakes things up red, orange, yellow, and pink petals. They are a branching variety that grows 10 to 12 feet tall.

Teddy Bear

Teddy Bear is another interesting variety. It’s a dwarf sunflower that maxes out at just over three feet tall. What really sets it apart is its frilly yellow petals that resemble a teddy bear’s fur.

Soraya

Soraya is a branching variety that produces up to 25 classic-looking sunflowers that are great cut flowers. Blooms mature over a few weeks, so you’ll have a steady supply of flowers.

Time to Plant Sunflowers

Now that you know how to grow sunflowers, it’s time to plant! Pick a location, order some seeds, and get ready to enjoy these happy blooms. Their use as a symbol of peace, inclusivity, and unbridled joy reinforces the notion that everyone deserves love. Show your appreciation, affection, or a little kindness with a bouquet of sunflowers that shine extra light on their day.

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