How to Grow Sunflowers in Southern California

Sunflowers are an easy-to-grow addition to Southern California gardens and a great way to add color to outdoor living areas. Use this step-by-step guide to learn how to grow sunflowers, the benefits of growing sunflowers, and what to do with the seeds and plants after harvest.

Benefits of Growing Sunflowers

Adding sunflowers to your yard is an easy way to add height, texture, and color to your landscaping. They are a cheerful addition that complements most architecture and landscape designs. They can spruce up a lackluster patio, hide an ugly fence, or add privacy to your outdoor living areas. But did you know that they also can be used to remove radiation from soil in contaminated areas?

Before we get into how to grow sunflowers, let’s look at 16 of the benefits they offer.

1. You can plant sunflowers to protect your garden or crops by attracting birds with their vibrant colors and tasty seeds.

2. Planting sunflowers to provide afternoon shade for food plants can help them survive the heat of Southern California summers.

3. Sunflowers add height to your garden and are great for planting in the back row of borders.

4. The height of sunflowers can help you block the view of air conditioning units, trash cans, or other unsightly things in your yard.

5. A row of sunflowers can increase privacy around your outdoor living areas.

6. Sunflowers are allelopathic, which means other plants do not grow well near them. This makes them a good choice for limiting weed growth.

7. If you like to watch squirrels frolic in your yard, you can plant sunflowers to attract them.

8. Sunflowers attract pollinators to your yard, which is good for your other plants, particularly those that produce food.

9. Sunflowers attract birds to your yard, which is good for bird watching and for pest control, since they will gladly eat insects while they are visiting.

10. Sunflowers are not considered toxic to humans, dogs, cats, or horses.

11. Sunflowers provide delicious, nutritious seeds that you and your family can enjoy.

12. You can also use sunflower seeds to fill your birdfeeders or simply allow the birds to eat them right off the flower.

13. Sunflowers are used for phytoremediation, which is a process in which plants are used to remove toxins, such as heavy metals and chemicals, from contaminated soil. Soil contaminants that can be removed by sunflowers include lead, cadmium, arsenic, chromium, and zinc.

14. Sunflowers make beautiful centerpieces and floral arrangements, so they are a solid addition to a cutting garden.

15. The root systems that help sunflowers stand tall add organic matter to the soil as they die and improve the soil structure for better water retention.

16. Sunflower leaves can be used as livestock feed.

Side note: If you are planting sunflowers to help remove toxins from soil you know to be contaminated, do not put the dead flowers, leaves, or stems in your compost bin or municipal yard waste bin. Also, do not feed the seeds, leaves, or any other part of the plant to birds or livestock.

How to Grow Sunflowers in Southern California

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Plant Sunflower Seeds in a Sunny Spot

Sunflowers thrive when planted in areas that receive at least six hours of sun each day. You can plant them to shade other plants that require protection from the heat, but make sure taller varieties will not block the sun from reaching nearby plants completely.

Protect Sunflowers from the Wind

Taller varieties of sunflowers require protection from the wind to help ensure that the stalks do not bend or break. If your yard is frequently affected by wind, consider planting your sunflowers near a structure, such as a fence or shed, that can provide some protection.

Prepare the Soil

Before you plant sunflower seeds, prepare the soil by adding compost or mulch and mixing it in at least the first foot of soil. While this is not entirely necessary with sunflowers, it is always a good idea to make sure any flowering plant receives adequate nutrients to help ensure that your plants are healthy and that you and your family can enjoy bigger blossoms and a better harvest.

Know-How and When to Plant Sunflower Seeds

You can purchase sunflower seedlings at a local garden center, but is easy and less expensive to grow them from seeds. Sunflowers grow well when the seeds are planted directly in your garden, especially in areas like Southern California. Just make sure that you plant them after the last frost in spring. They grow best once the soil temperature has reached between 70 and 85 degrees.

Before planting sunflower seeds, place them in a plastic bag or food storage container with a wet paper towel for a couple of days. Do not seal the bag or container, and add water as needed to keep the paper towel moist. After a couple of days, look for the seeds that have sprouted, since these will be the best ones to plant in your garden to start seeing sunflowers soonest.

Plant seeds about one inch deep and about six inches apart in rows spaced two to three feet apart. If you are planning on cutting the flowers for use in arrangements or harvesting the seeds, plant some of your seeds every two weeks so that you will have a longer harvesting period.

Thin Sunflowers as They Grow

If you mostly plan on cutting your sunflowers for arrangements, you can allow them to grow closer together – even as close as about three inches apart – which will result in smaller flowers, but you will have more of them to adorn vases around your house.

If your main goal is to have a good harvest of seeds or to grow your sunflowers as tall as possible, you will need to thin them to about one foot apart to give each one room to grow and thrive.

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Protect Seeds and Plants from Wildlife

As soon as you plant sunflower seeds, any nearby rats, mice, birds, squirrels, or snails will be happy to dig them up and eat them. This means that you will need to protect your seeds and give them a chance to grow by using a barrier to keep wildlife away from them. Hardware cloth laid over the ground is a good deterrent that should do the job.

If you have deer that frequent your garden, you will also need to protect your plants from these visitors, which you can do by using chicken wire around the flowers and stalks to act as deer fencing to keep them out.

Once your flowers produce seeds, you may want to cover the flowers loosely with a material that allows for good airflow to protect the seeds from birds and squirrels. Pantyhose are a popular choice for this, since bird netting can cause injury or death to birds that get trapped under it.

Water Sunflowers Properly

Sunflower seeds take about one to two weeks to germinate. During this time, you will need to keep the soil moist. As your plants grow and become established, start reducing the number of times you water them until you are down to one day per week. Their extensive root systems make sunflowers partially drought tolerant, so one day per week should be good for most of the year. During times of drought or excessive heat, you will need to increase irrigation accordingly.

Support Tall Varieties

Taller varieties of sunflowers may need support as their height increases and the flowers begin to weigh more. Your sunflowers may also need support if you live in a windy area. You can support sunflowers by staking them or by using twine to attach them to a nearby fence, tree, or structure.

Know When to Harvest Seeds

We will discuss how to harvest and use sunflower seeds in the next section. The first step is knowing when to harvest them. Signs to look for to know when to harvest sunflower seeds include the seeds darkening in color, the small petals covering the seeds drying and shriveling, the back of the flowers turning from green to yellow-brown, and the flowers beginning to droop. When you see these changes happening, it is time to harvest the seeds and remove the stalks.

Compost Remaining Leaves and Stalks

Once you have harvested the blossoms for seeds, remove the rest of the plant, cut it into manageable pieces, and add it to your compost bin. Keep in mind that you should not add it to your compost bin if you planted the sunflowers to clean up contaminated soil. In that case, you will either place the dead sunflowers in your trash bin or, if your soil was particularly contaminated, you may need to dispose of them as hazardous waste.

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How to Harvest and Use Sunflower Seeds

Folks who are growing sunflowers to use as cut flowers can simply harvest the stems and blossoms as needed.

Those who are growing the seeds to attract wildlife to their yards can either leave the flowers uncovered for birds and squirrels to enjoy while they are on the plant or you can harvest the flowerheads and leave them around your yard with the seed side facing up so that critters can access them. Please note that this will attract all sorts of critters to your yard, including some that you might not want there, such as rats and mice.

Alternatively, you can remove the seeds from the flowers and scatter them throughout your yard, which will attract birds and squirrels but will also attract unwanted animals. The best option for sharing them with wildlife in your yard is to add them to a birdfeeder or squirrel feeder to hopefully just attract the animals you would like to see more of while not providing easy food for animals you do not want in your yard or garden.

If you are harvesting the seeds for use as food for you and your family, cut the stalks about one foot below the flowerheads. Use the attached stalk to hang the flower upside down in a warm, dry area to allow the seeds to dry for a few weeks. Moisture can cause mold growth or spoil your seeds, so be sure to choose a dry spot for drying your sunflowers.

Once the seeds have dried, remove them from the flower by using a brush to knock them loose or by rubbing two flowerheads together. Lay out parchment paper or baking sheets so that you can spread out the seeds to dry further.

If you plan on using them raw or if you are saving them to plant next year, or saving them to use in your birdfeeder over the next few months, store seeds in mason jars once they are completely dry. If you prefer roasted sunflower seeds, heat your oven to 350 degrees, spread the seeds out on baking sheets, and roast them for 10 to 15 minutes. When they are turning slightly brown, you will know they are done.

To make roasted and salted sunflower seeds, soak the seeds in saltwater overnight, drain them, pat them dry, and then spread them out on baking sheets before roasting them.

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How to Use Sunflower Seeds, Roots, Stalks, Leaves, and Petals

You can always plant sunflower seeds just for looks, but if you would like to harvest and use your sunflowers, here are some suggestions you might try.

  1. Sunflower roots, petals, and seeds can be used to make herbal teas.
  2. Add sunflower seeds to salads or eat alone to benefit from their iodine, vitamin E, iron, potassium, protein, magnesium, vitamin B, and vitamin C.
  3. Harvest sunflower seeds to add to birdfeeders to feed wild birds and attract birds to your yard.
  4. Steam sunflower leaves for a flavorful side dish.
  5. Add sunflower leaves or stalks to salads or stir-fries.
  6. Roast the seeds for a healthy snack.
  7. Harvest the seeds to make your own sunflower oil.
  8. Use the seeds to make sunflower seed butter, which is a nut-free alternative to peanut butter or almond butter.
  9. Grind sunflower seeds to make nut-free, gluten-free flour.
  10. Make sunflower milk out of the seeds.
  11. Use the seeds to make dairy-free sunflower seed cheese.