Get It Growing: Sunflowers Are Easy To Grow, Offer Variety And Thrive In Heat Of Summer

Daniel Gill, Merrill, Thomas A.  |  6/30/2007 12:14:28 AM

Get It Growing News For 07/27/07

By Dan Gill
LSU AgCenter Horticulturist

If you haven’t paid a lot of attention to sunflowers for your garden lately, you may think only of the gigantic sunflowers that reach for their namesake in the sky – towering to heights of 8 feet or more.

You also may think they only come in yellow.

The truth is that today’s gardeners have a lot of choices when selecting sunflowers for color, height and use as cut flowers. In addition, sunflowers that produce edible seeds are great for producing a late-summer crop of sunflower seeds.

Sunflowers are among the easiest flowers to grow and thrive in the heat of our summers here. In fact, as many people have noticed, sunflowers often come up from seeds put out as bird food – so how hard can they be to grow?

This quick easy growth is why children often are so delighted with sunflowers. Depending on the cultivar, sunflowers will bloom anytime from about 55 days to 75 days after planting the seeds. (Check the seed package information.)

Sunflowers can be broadly divided into those that are grown for production of edible seeds and those grown as ornamentals and for cut flowers.

You can start sunflower seeds in small containers, with drainage holes, filled with potting soil. Locate the containers in full sun to produce strong, stocky transplants. Make sure you water regularly, and never allow the soil to become dry. When the seedlings have grown to about 4 inches to 6 inches high, transplant them to sunny flower beds.

You also can sow the seeds directly into a prepared garden bed in full sun. After sowing the seeds, water the bed well, and then water the bed as needed to keep the soil moist. (Water lightly every day if the weather is dry.)

When preparing a bed for either transplants or direct-seeding, incorporate a 2-inch to 4-inch layer of organic matter (compost, rotted leaves, manure or peat moss) and a light sprinkling of general-purpose fertilizer into the bed. When planting transplants, water them in with a soluble fertilizer mixed with water so that it’s half strength.

To encourage maximum growth, fertilize with a soluble fertilizer once or twice a month, or apply a light application of the general-purpose fertilizer about six weeks after planting the bed.

A Cut Above

Sunflowers grown for cut flowers generally produce numerous flowers on a more bushy plant than those types grown for seeds, which generally produce a single, large head. The multiple flowering habit makes these cut-flower types more colorful, and they fit into traditional flowerbeds more appropriately.

While brilliant yellow always will be popular, you also can choose from creamy white, bronze, mahogany, rusty red, burgundy and orange – with some types producing flowers with more than one color.

Cut sunflower blossoms before they are fully open and place them immediately into water. The shedding of pollen is sometime a problem, and the pollen can stain fabric if it gets on it. But several cultivars for cut flowers have been bred not to produce pollen. A few pollen-free cultivars include Chianti, Strawberry Blonde and Sunny.

The Seedy Side

If you want to grow sunflowers for the delicious, nutritious seeds, make sure you choose cultivars bred for seed production, such as Mammoth Russian (also known as Mammoth, Russian Giant and Gray Stripe). These tall-growing sunflowers produce a single, enormous flower at the top of the plant.

To grow a really big seed head, make an application of general-purpose fertilizer when the flower head begins to appear.

When growing tall sunflowers, you also may want to provide a tall, strong stake driven well into the ground for support. As the seed heads mature they get heavier, and strong winds may blow the plants over if they aren’t supported.

As the seeds mature you have to make a choice about whether you want the seeds all to yourself or if you are willing to share them with the birds and squirrels. If you don’t want to share, you will have to cover the seed heads with cheesecloth or an old nylon stocking to keep the animals at bay. Watch the birds – when they start to visit, it is time to cover the heads.

Covered seed heads are ready to harvest when the bracts behind the head turn brown and the back of the head is greenish-yellow to yellow. Leave about 1 foot of stem attached and hang the seedhead in a warm, well-ventilated place. When the back is entirely brown, remove the seeds by brushing them out with your hands or a stiff brush.

Do not wash the seeds before storage, because washing might promote rot. Store the seeds in air tight containers in your refrigerator to maintain flavor and nutrition.

Share The Wealth

Sunflower seeds are excellent food for the birds and other animal life in your backyard. Once the seed head has matured, you can simply leave the plants in the garden for the animals to have fun with, or you can cut it off and let the whole head dry out as described above.

Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at A wide range of publications and a variety of other resources are available.


Contact: Dan Gill at (225) 578-2222 or
Editor: Tom Merrill at (225) 578-2263 or

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