Sunflowers are some of the most popular flowers to grow. And understandably – they look amazing! They bring some cheer to any garden.
Growing them isn’t too difficult either. So even if you’re someone who has been gardening for years or just getting started this guide will take you through everything you need to know to grow some gorgeous sunflowers.
Choosing the Right Sunflower Variety
Before you can begin planting your sunflower you’re going to want to choose a type. There are many varieties and some will suit your garden or situation better than others.
Popular Sunflower Varieties
- Mammoth: Known for its large size (as the name gives away). They can reach up to 12 feet tall with flower heads that are up to 12 inches across. If you want a sunflower that everyone notices in your garden then this is the one to get.
- Dwarf Sunspot: Perfect for small gardens or containers as they only reach about 2 feet in height. They are easy to manage and if you’ve got a tiny area they can really liven it up.
- Teddy Bear: A bushy type with fluffy, double blooms that look like golden pom poms. They grow about 2 to 3 feet tall and work really well along borders or in children’s gardens.
- Autumn Beauty: A bit different from some of the others, Autumn Beauties have multi branched stems and flowers that come in lots of colors.
- Velvet Queen: Known for its very distinctive dark red blooms, it reaches about 5 to 6 feet tall and stands out with the prominent colors.
- Italian White: A more sophisticated looking sunflower, the Italian White has dark centers that contrast against it’s white petals. Grows to 5 to 6 feet tall and is very elegant.
Preparing Your Garden
Sunflowers adapt well but preparing your garden beforehand won’t hurt and can make sure they really thrive.
Soil Preparation
Sunflowers prefer soil that drains well and that has a pH between 6.0 and 7.5. Prepare your soil by:
- Test the soil: Use a pH test kit to check your soil’s acidity. You want a neutral to slightly acidic pH for sunflowers.
- Fix if necessary: If your soil is too acidic add some lime to it. For soil that’s too alkaline add sulfur. Base which you add and how much on the results of testing your soil.
- Enrich the soil: Add compost or well rotted manure to improve the fertility of the soil. It will help make the soil hold on to moisture as well as giving nutrients as it breaks down.
- Tilling: Till the soil to a depth of about 12 to 15 inches to loosen it. Remove any rocks, stones or anything else that might get in the way of the roots and affect their growth.
Choosing the Right Spot
Sunflowers do best in full sunlight. You should be aiming for them to get at least 6 to 8 hours of direct sun each day. They also like spots that are sheltered and where they can’t be knocked over by any strong winds.
- Sunlight: Pick a spot that gets the most amount of sunlight. Sunflowers need that high level of light to grow tall and produce large flowers.
- Wind Protection: Sunflowers are tough but they can still be vulnerable to strong winds. To avoid this being a problem plant yours near to a fence or use windbreaks if your garden gets a lot of wind throughout.
- Space: You don’t want to overcrowd your sunflower so make sure it had enough space to grow. The taller the variety the more room they will need to spread out.
- Soil Drainage: Having good drainage is very important to prevent the roots rotting. So avoid planting in low lying areas that the water might collect in.
Planting Sunflowers
When to Plant
It’s best to plant your sunflower after the last frost. This is when the temperature of the soil will be around 50 to 60°F (10 to 15°C). This is usually between late spring and early summer.
- Check Frost Dates: Know when your area is going to get frost and make sure that you do your planting after the danger of any frost has passed.
- Soil Temperature: Use a soil thermometer to check the temperature. Sunflowers prefer warmer soil to sprout well.
- Succession Planting: For continual flowering you can plant the seeds every two weeks until the mid summer.
Planting Seeds
Plant sunflower seeds directly in the ground. To get the best results follow these steps:
- Spacing: Space the seeds about 6 inches apart for the regular sized varieties. If you’ve chosen a larger variety then make the spacing a bit bigger. 12 to 18 inches will be enough for their bigger size.
- Depth: Plant seeds about 1 inch deep. If your soil is heavier then plant the seeds a little shallower. This will give them a chance to push through the surface of the soil.
- Rows: Keep the seeds 2 to 3 inches apart if you’re planting multiple rows of them. This is to let the air circulate fully around them and give you easier access.
- Thinning: Once the seedlings are about 6 inches tall thin them to the strongest plants. Whatever the variety you’ve chosen needs space them on that basis. Thinning is important because it stops overcrowding and makes sure each plant gets enough space and nutrients.
Watering and Fertilizing
Sunflowers have deep roots and are tough. So they don’t need too much in the way of care. But getting their watering and feeding right can make a big difference to how well they grow.
Watering Tips
- Consistent moisture: Keep the soil moist (not damp). This is especially important as the seeds are germinating. And make sure you stop the soil from drying out completely between waterings.
- Deep watering: Deep watering is good because it encourages the roots to grow deeper too. This will help your sunflower to be able to get through dry spells. A deep watering once a week is better than giving them a shallow watering but doing it more often.
- Avoid overwatering:
Too much water can lead to root rot. So be sure that your soil is draining well. Check your soils moisture level by putting your finger in about inch. - Mulching: Mulching will keep the soil moist and maintain it’s temperature. So apply a layer of it to the base of your sunflower.
Fertilizing
The occasional feeding can really help sunflowers even though they aren’t massive feeders. Use a balanced fertilizer and follow these tips:
- Early growth: Apply a balanced fertilizer (10-10-10) when the plants are about 1 to 2 feet tall. This will give your sunflower the main nutrients it needs for early growth and development.
- Flowering stage: Switch to a fertilizer that is rich in phosphorus (5-10-10) as the flower buds form to help with the blooming. Phosphorus supports the flowers developing and strong root growth.
- Avoid too much nitrogen: Too much nitrogen can result in great foliage but fewer flowers. Follow the recommended dosage on the fertilizer package.
- Organic options:
You can use organic fertilizers like compost tea or fish emulsion for a more natural approach.
Supporting Your Sunflowers
Tall sunflowers can become too heavy at the top, which is especially a problem when there’s a lot of wind. So supporting your sunflower becomes important.
Staking
- Choose sturdy stakes: Use wooden or metal stakes that are at least 6 feet tall. The stake should be strong enough to support the weight of the sunflower as it grows.
- Secure gently: Tie the sunflower stem to the stake with soft twine but make sure you give it eboifh room to grow still. Don’t tie it too tightly though as this can damage the stem.
- Positioning: Place the stake about 2 to 3 inches away from the stem to avoid damaging the roots when you insert the stake into the ground.
Netting
If you’re growing multiple or patches of sunflowers you can use garden netting to support multiple plants at the same time.
- Setting up netting: Install garden stakes around the sunflower patch and drape the netting over the stakes for overall support.
- Adjust: The netting will need to be adjusted to allow for the growth of the sunflowers and so that it doesn’t restrict their movement.
Pest and Disease Management
Sunflowers are generally strong but they can still be affected by pests and diseases.
Common Pests
- Aphids: These tiny insects can be controlled with insecticidal soap or by bringing on natural predators like ladybugs. Check your plants regularly and spray the affected areas as needed.
- Caterpillars: Handpick them or use biological controls like Bacillus thuringiensis (Bt). Look for them on the undersides of the leaves and remove any you find.
- Birds: Cover the flower heads with netting if birds become a problem. You can also use shiny objects or scare devices to keep them out of your garden.
Common Diseases
- Powdery mildew: Good air circulation and not watering from overhead will help to avoid powdery mildew. Remove the affects leaves if you spot it and use fungicide if you need to.
- Rust: Make sure the sunflowers are properly spaced and don’t let the soil get waterlogged.
- Downy mildew: Similar to powdery mildew – avoid waterlogged conditions and improve the airflow. Use resistant varieties if you can.
- Fungal infections: Rotate your sunflowers annually so they don’t get soil borne fungal infections. Don’t plant sunflowers in the same spot every year.
Harvesting Sunflowers
If and when you want to harvest your sunflower then getting the timing right is the most important part.
Harvesting for Seeds
- Wait for maturity: The back of the flower head will turn yellow or brown and the seeds will be plump and loose. This is a clear sign that the seeds are mature and ready to be harvested.
- Cut the head: Use sharp scissors or pruners to cut the flower head off. You’ll want to leave about 12 inches of stem. Be careful with flower heads so you don’t lose any of the seeds.
- Drying: Hang the flower heads somewhere dry that has good ventilation until they are completely dry. Place a paper bag or cloth underneath to catch any falling seeds.
- Collect seeds: Rub the seeds off the flower head. Store them in an airtight container. If you plan to replant them then store them in a cool, dry place.
Harvesting for Floral Displays
- Cut at the right time: Harvest when the petals are just beginning to open to get the longest vase life. Flowers cut too early or too late probably won’t last as long.
- Use clean tools: Make sure your scissors or pruners are clean to prevent any diseases from being spread. Sterilize your tools before and after use.
- Immediate care: Place the cut flowers in water immediately. Use clean water and add flower preservatives to give them a longer life when in a vase.
- Recut stems: Recut the stems under water to prevent air bubbles from entering the stem which can block water uptake.
Companion Planting
Getting the companion planting right – growing plants together that help each other out – will be of benefit to your sunflowers.
Good Companions
- Cucumbers: Sunflowers provide a natural trellis for cucumbers to climb. Together this means they can support each other and it will save space in your garden.
- Squash: The large leaves of squash will keep weeds from growing around the base of sunflowers. This will keep the soil moist and reduce the competition in the soil.
- Beans: Beans fix nitrogen in the soil which can benefit sunflowers. It will contribute to them growing bigger and stronger.
- Marigolds: will keep away pests like aphids and nematodes.
Bad Companions
Avoid planting these with your sunflowers:
- Potatoes: Sunflowers can attract pests that also target potatoes. To stop infestations don’t plant these two together.
- Fennel: Always a problem as it it stops the growth of many garden plants, including sunflowers.
- Tomatoes: Both plants are susceptible to similar diseases. Keep them apart so they don’t infect each other.
Frequently Asked Questions
Can I Grow Sunflowers in Containers?
Yes. Choose a dwarf variety and use a large pot with good drainage. The container will need to be at least 12 inches deep and wide to be big enough for the roots.
How Long Do Sunflowers Take to Grow?
Most sunflowers take about 70 to 100 days to bloom. It will depend on the variety and conditions they’re grown in though.
Do Sunflowers Need Fertilizer?
Sunflowers can grow in less fertile soil. But a balanced fertilizer can help to boost their growth if your soil isn’t great
Why Are My Sunflowers Wilting?
Wilting can be due to overwatering, underwatering or root rot. See if the soil is moist enough and whether it’s draining well.
How Can I Prevent Birds from Eating My Sunflower Seeds?
Cover the flower heads with garden netting or paper bags as they mature to protect them from birds.
Final Thoughts
Growing sunflowers doesn’t need be hard. All it takes is a little care and attention and doing things the right way. Do that and you will get to enjoy sunflowers all season long.
