The Beginner's Guide to Planting Sunflower Seeds
Planting sunflower seeds is one of the most joyous things we can do. The bright flowers and tall stalks offer beauty in the garden and as cut flowers in the home. The birds and bees will thank you as well. They’re easy to grow and well worth your time. Not to mention, there’s a sunflower for every garden - whether you want flowers that are ten feet tall or three feet tall and branched, there’s a variety for you!
Benefits of Growing Sunflowers
Besides the beauty of sunflowers, there are many other reasons why you may want to include this regal crop in your garden!
Phytoremediation
Sunflowers have been shown to be effective in phytoremediation, which is the process of using plants to clean up contaminants in the environment and soil. They can take up metals, pesticides, and other pollutants and remove them from the soil. These plants, of course, should not be ingested or composted and should be disposed of in the trash.
Companion Planting
Sunflowers can assist in the growth of other plants through a practice called companion planting. Companion planting is simply the practice of interplanting different crops that may benefit each other in a myriad of ways whether it's pest control, nutrient sharing, or encouraging pollination. Sunflowers, due to their height and stature, can help to offer shade to crops that may easily become sun stressed such as beans, basil, or fall crops of lettuce, spinach, and kale. It’s also sometimes considered the fourth sister of the well known three sisters - corn, beans, and squash - as they can help hold up heavy corn stalks and protect them from wind damage. Just keep in mind, when companion planting with sunflowers, that they are heavy feeders so when planted near other heavy feeders, some extra fertilizer may be necessary for adequate development of all crops.
Understanding Sunflower Seed Germination
Sunflower seed germination is not so different from other seed germination. There are certain environmental factors that will benefit the germination rate of your sunflower seeds and some things that need to happen in order to break seed dormancy.
In order for seeds to germinate, the seed coat needs to be broken. In most cases this is done with adequate moisture. As the seed is taking up water, it begins to swell and then breaks open the seed coat. The root emerges first and takes up the job of absorbing moisture. Eventually, the cotyledons pop up! Not watering enough is the number one reason folks have trouble germinating seeds.
Preparing Your Garden for Sunflowers
Sunflowers will grow best in well-draining soils; however, they are tolerant of some clay soils. You may consider amending your soil with sand, compost, or other amendments four to six weeks before planting. They may perform better with some acidity but don’t need it in order to grow. Sunflowers are heavy feeders and so will appreciate lots of balanced fertilizers as they grow.
Best Times and Conditions for Planting Sunflowers
Sunflower seeds will typically germinate within five to 12 days from planting under the right conditions. They are a warm season annual and will appreciate being planted in soil that is between 55 and 60 degrees fahrenheit. You can also plant sunflowers inside early and transplant them after all danger of frost has passed. This would mean that your plants would flower sooner than other gardeners! Many growers will transplant sunflower seedlings but note that in general, sunflowers do not like having their roots disturbed, so they may actually grow better when direct seeded.
Whenever you’re planting sunflowers during the frost-free growing season, take note of the Days to Harvest information found on your seed packet. It can vary depending on the variety: Mammoth Grey Stripe which can reach 12 feet tall takes between 90 and 100 days to mature, whereas Sunspot Dwarf only takes between 60 and 70 days.
Sunflowers will do best when planted in full sun. Partial shade can cause sunflowers to be leggy and more leaf than flower. Sunflowers are a great example of heliotropism - which is the directional growth of a plant in response to sunlight. Sunflower heads move throughout the day, following the sun as it moves across the sky (basically magic - right?). When sunflowers are in shade, the flowering heads may droop and face the ground in an attempt to maximize sun exposure.
How to Plant Sunflower Seeds Effectively
When planting sunflower seeds, seed them about an inch deep and six inches apart. Once the seedlings are six inches tall you can thin them to be eight to 12 inches apart. The benefits of planting closer together and then thinning include getting the highest germination you can and not wasting any space, while allowing your plants to mature without competing with each other for nutrients or sunlight.
Dealing with Common Sunflower Growing Challenges
Just like any crop, sunflowers have pest and disease issues that you may come up against while you’re growing them. Luckily, with a little proaction (and the speedy germination rates if you end up needing to re-seed), you can handle anything that nature throws at you!
We love to eat sunflower seeds and many pests do too. Seeds may go missing as birds come hunting for snacks or deer may come by and eat your whole seedling or defoliate larger plants. These larger pests can be somewhat difficult to manage but straw or bird netting will help your seeds reach germination, and fencing or trap crops may save them from deer! Birds and squirrels will also love the seed heads once your plants mature but you can cover the heads with pollination bags or other white fabric to protect the seeds as they mature to harvest.
Sunflowers are susceptible to many common fungal diseases that typically come later in the season. Downy mildew, powdery mildew, and fungal rust can all affect sunflowers. These issues are best treated with proactive steps such as watering in the morning to reduce moisture sitting overnight and planting at appropriate distances to encourage airflow. If you start to notice fungal diseases showing up on your sunflower leaves, remove them and dispose of them to reduce the spread. But keep in mind! Many fungal issues will not cause problems with flower or seed production. These diseases can kill the plants but typically they show up late enough in the season that your sunflowers will still mature.
Grow Your Own Sunflowers
There are so many different varieties of sunflowers to grow whether you want unique sizes, statures, or colors. Every sunflower is perfect for beginners so just follow your grower’s heart and choose the one that calls out to you!
Chocolate Cherry
These six to seven foot sunflowers have deep burgundy to mahogany colored petals on five to eight inch flower heads. They’re a stunning cut flower with low pollen meaning they won’t powder your tabletops with (as much) yellow powder.
Sunspot Dwarf
These sweet plants reach two feet tall while offering stunning ten inch, bright yellow blooms. They’re perfect for small spaces or when you want to avoid shading out other crops.
Mammoth Grey Stripe
On the other hand, meet Mammoth Grey Stripe, the six to 12 foot tall monster of a sunflower with gorgeous, giant flower heads. These are typically grown for their meaty seeds which are great for roasting or sharing with the birds!
Carousel
This sunflower is perfect for small spaces or containers as it produces a branching, bushy pattern of sunflowers on a single plant!
Teddy Bear
By far the cuddliest sunflower! Teddy Bear Sunflowers get to be two to four feet tall and produce multiple flower heads per plant.
Growing sunflowers is easy and rewarding for a crop of seeds or cut flowers. Don’t let them intimidate you - grow sunflowers today!
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Article Written by: Hannah Gibbons |
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About the Author: Hannah Gibbons, an employee at Sow True Seed since 2020, has nearly a decade of experience in the agricultural industry. Their passion for environmental education and regenerative agriculture has been the cornerstone of their work, aimed at making gardening accessible to all. |