If you want to grow sunflowers, you need to know when to plant sunflowers and what they like for growing conditions: in addition to lots of space, there are some plants they do not like to be near. Planting sunflowers is easy and the birds love these beautiful flowers.
If you want to find interesting sunflower seeds to sow, see recommended seed companies in the United States and Canada.
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Sunflowers (Helianthus) are annuals so you need to sow new seeds each year. Seeds from previous seasons may also germinate where they have landed in your garden, including fallen seeds from birdfeeders or buried by squirrels.
When to Plant Sunflowers
- If you are sowing your seeds outdoors, sow them as soon as the risk of frost has passed.
- You can also start the seeds indoors about two weeks before last frost and transplant them outdoors.
How to Find Your Frost Dates and Hardiness Zone
- Frost Dates Calculator | This calculator at Almanac.com is simple to use. Enter your city and state or province to find your first and last frost dates and number of frost-free days.
- Plant Hardiness Zone | United States and Canada
Plant hardiness zones are listed on seed packets and plant tags.
Provide Adquate Growing Space
- Sunflowers are incredible resource hogs, as you can well imagine since they need a lot of fuel to grow those massive flower heads filled with seeds.
- Check your seed packet for recommended sowing distances as this varies greatly depending on the mature size of the sunflower.
- In general, a mammoth (tall, giant) sunflower does best in good quality soil with no other plants within 24-inches (two feet) in any direction (a four-foot diameter circle of growing space).
- Smaller varieties of sunflowers are more forgiving, with some doing fine with just 6-inches of growing space (in all directions). But more is better. The better the resources, the larger the plant can grow.
Companion Planting – Good and Bad
If you’ve familiar with the idea of companion planting you know that plants are sensitive to their surroundings. Not just the soil quality, amount of sun, and moisture levels, but which other plants are growing nearby. Some get along just fine, others benefit one another, and a few compete for resources.
Simply put, sunflowers produce compounds that inhibit growth in some other plants, stopping seed germination and growth.
The two plants known to be negatively affected by sunflowers are:
- pole beans (that climb like vines)
Both may struggle if planted too close to sunflowers.
Plants that benefit from sunflowers growing nearby are:
But do allow everything enough root space, of course. Your seed packet will have sowing instructions.
- Pick a full-sun location
- Provide fertile, well-drained soil
- Allow ample space between plants: seed your seed packet for specific instructions
- Cover the soil with heavy mulch
- Add a cloche or mesh cover to protect the plant from hungry birds and critters until it is several inches tall
- Grow in-ground or in large containers
Did you ever notice this?
While young, sunflower seedlings will move to face their light source. Once blooming, they remain in place. The tracking of the sun in young sunflowers is called heliotropism. Most end up with the flower heads facing east. Good morning!
Growing Sunflowers for Cut Flowers
If you want to use your sunflowers in cut flower displays, choose the smaller single-head varieties. There are also pollen-free options available if mess or allergies are a concern.
A tall, sturdy sunflower makes a great cucumber trellis! Start the cucumber two feet away and gradually train it up the sunflower stalk as it grows.
Choosing Sunflower Seeds
With over 70 species, there are many choices: size, colours (from pale yellow to bold reds and oranges), appearance, volume of seeds they produce, number of flower heads on each stalk. The tiny ones reach about 2 feet tall. The world record for sunflower height is currently 27 feet!
You can see sunflower seeds here on Amazon or, better still, find a good local seed company listed here for the United States and Canada.
Remember to leave your sunflowers in the garden so the flowers can turn to seed. This provides nourishment for birds all through the winter.
~Melissa the Empress of Dirt ♛