How Far Apart to Plant Huge Sunflower Plants?

Spacing

• The giant sunflower needs to be spaced at 20 inches to 3 feet apart with rows at about 4 feet apart. Regular-sized sunflowers still need quite a bit of room between them at 2 feet apart while miniature sunflowers should be spaced at 1 foot apart, both needing about 3 feet of space between the rows. Sow the seeds directly into the soil after the last frost in clumps of six about an inch deep. Thin seedlings, leaving the strongest seedling.

Growing Considerations

• Giant sunflowers prefer at least six to eight hours of direct sun per day. They also need well-drained soil that is nutrient-rich. Dig a hole about 2 feet deep and fill with compost and/or manure along with the soil. Regularly apply liquid fertilizer. Deeply water the sunflowers, making sure not to soak the soil and don't let the soil dry out. You will also have to stake the flowers so they don't fall over.

Animal Problems

• The giant sunflower attracts birds and squirrels that like to feast on the seeds. Consider putting a net over the area. Rabbits and deer enjoy eating the plants when they're small, so you may have to protect against them as well.

Varieties

• Mammoth is the most common variety of giant sunflower that grows from 7 to 12 feet with a flower head measuring more than a foot across. Sunzilla is a hybrid, which is chosen for its uniformity and reliability. The California Greystripe grows from 9 to 12 feet with a flower diameter of up to 13 inches. The American Giant variety is a hybrid that grows very tall -- up to 16 feet -- but with smaller flower heads at 10 inches.