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How to Grow Sunflowers

Nothing says summer quite like the bright yellow faces of sunflower plants. Growing sunflowers is easy as they are heat tolerant, resistant to pests and are remarkably tough. Seeds can be harvested in the fall and are a great snack with an irresistible flavor and satisfying crunch. 

They're excellent for appetizers, salads, desserts and other dishes. If you choose not to harvest sunflower seeds, the birds in your yard will love you! It doesn't take long to discover how growing sunflowers will perk up your garden, your dinner plate and your health. Although admired as an ornamental, sunflowers actually have an amazing variety of uses.

Choose Your Sunflower Variety and Plant in Full Sun

Consider planting sunflower seeds indoors before the last frost to get a head start on the growing season. However, the plants have long tap roots, so if you do start indoors, be sure you can plant outside by the time the seedlings have two leaves. This helps to ensure you don't damage the tap root.

Planting sunflower seeds indoors will mean the young plants need to harden before being transplanted outdoors. Put them out during the day to allow the weather to thicken the stems, but return them indoors overnight. The plants may need up to two weeks to harden before being transplanted into the ground.1

Planting sunflowers seeds in direct sunlight, or an area of your garden getting six to eight hours of sun per day, is best for the health of your plants. Choosing the right spot may be one of the most challenging parts of growing sunflowers as the plants are heliotropes and follow the sun's path across the sky.2

Interestingly, this movement is triggered by the plants internal hormones in much the same way your circadian clock is ruled by hormones. There are several varieties of sunflower plants. The taller types can cast a long shadow in your garden, so plant these on the north side of your garden plot, unless you want to supply shade for other plants.

The American Giant and a couple other varieties will grow as tall as 15 feet with flower heads spanning 1 foot across.3 However, if you don't have a large space, you still have the opportunity to plant sunflowers, since dwarf varieties will measure only 1 or 2 feet tall.4 Medium height sunflower plants will stand between 5 and 8 feet with heads up to 10 inches across. 

Some varieties produce a single large flower, while others will form several heads. Not all sunflowers have yellow flowers. Little Becka and Terracotta have red tinged flowers and Ms. Mars and Chianti grow in shades of purple.5 In other words, you have several choices to make before you begin growing your sunflower seeds.

Sunflower Plants Have Soil and Water Preferences

Although hardy and easy to grow, sunflower plants have soil and water preferences to support their growth and provide you with a strong harvest. If you've chosen a low-growing variety, give them plenty of room as they branch out. Plant your seeds no more than 1 inch deep and 6 inches apart when planting outdoors, and transplant your strongest seedlings between 6 and 8 inches apart. 

A light application of organic compost mixed into the soil at the time of planting will encourage strong roots and protect young tender plants from blowing over in the wind. Add mulch as the plants reach 6 inches to minimize weed growth and conserve water. While drought resistant, you'll have a greater sunflower seed harvest if the plants receive sufficient water.6

Consider planting sunflower seeds staggered over five to six weeks so you'll continue to enjoy blooms through the summer and get a strong harvest in the fall. Don't over fertilize the plants as they are not heavy feeders.7 Over fertilization may cause weaker stems to break once the tops get heavy with seeds.8

Once the plants are established, water thoroughly but infrequently to encourage deep rooting. As the plants grow taller, water once a week with several gallons of water unless the weather is exceptionally wet or dry and then adjust as needed. Taller plants may need bamboo supports that must be buried deep in the soil to provide enough support in windy conditions.9

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