Do You Have Sprout the Sunflower First for It to Grow Large?

Starting in Pots

• Get a head start on the summer growing season by starting sunflower seeds in pots indoors. Fill 3- or 4-inch pots with good quality potting soil and plant one seed in each pot about 1 inch deep. Keep pots in a sunny location and transplant to the garden when they are about 6 inches tall and the final spring frost has passed. Transplant your sunflowers after the sun has left your garden for the day and protect them from slugs and snails by surrounding the young plants with iron phosphate granules.

Sunzilla

• With bright golden petals, this one ranks among the largest of all sunflowers. Plants form strong talks in order to support the enormous flower heads that form up to 16 or 17 feet above ground level. A quick grower, Sunzilla blooms in late summer or fall and does best when you plant wither seeds or young plants in soil that contains organic compost. Sunzilla makes a good privacy hedge when you plant multiple seeds 12 to 18 inches apart. If you harvest the seed heads before the local songbirds eat them, you'll have plenty of seeds for next year's planting and for snacks.

Mammoth

• This is another variety of very large sunflower, reaching a height up to 10 feet and producing flowers that measure 24 inches across. Plant seeds ½ inch deep and 4 to 6 inches apart -- you'll be thinning weak plants later, so plant as many as you want. When young plants are 4 to 6 inches tall, thin them to leave about 18 inches between individual plants. This variety, like other sunflowers, needs plenty of water during its summer growing season.

Giant Greystripe

• Although this sunflower grows to only 8 feet tall, it produces flowers that measure up to 12 inches in diameter and produce copious quantities of seeds. Seeds are good to eat raw or roasted and salted. Expect seeds to sprout within two weeks of planting -- this variety thrives best when you plant seeds directly into the garden outdoors. Help your plants to grow extra large by fertilizing them with a balanced plant food every week. After 80 to 100 days of growing, you'll be snipping the seed heads off the plant and using them for snacks, in recipes, or to feed chickens and wild birds.