Anyone can grow sunflowers. In
fact, sometimes you don't even have to plant them at all .. they
sprout up all by themselves as "volunteers." However, if you
want to have the best chance of growing a giant sunflower, here are
some gardening tips to help.
Sunflowers need full sun, 6-8 hours of direct
sunlight per day—the more the better if you are trying to grow them
to their maximum potential.
Choose a well-drained location, and
prepare your soil by digging an area of about 2-3 feet in
circumference to a depth of about 2 feet. Sunflowers are heavy
feeders and deplete the soil more than many other crops—especially
if you are growing them to reach a massive height—so the nutrient
supply must be replenished each season.
Depending on your soil, you may wish to add, in addition to
composted manure a slow release granular fertilizer—one that also contains
trace minerals-- about 8” deep into your soil. Woodland plant
geneticist Tom Heaton uses a mineral
fertilizer such as Osmocote. If you are an organic gardener, a balanced slow-release granular fish fertilizer
Sowing Seeds - When and How
Since sunflowers that are planted in
midsummer (July and August) often flower on shorter stalks, sow your giant sunflowers
earlier-as soon as all danger of frost is past and night
temperatures are above 50 degrees Fahrenheit both day and night.
To grow the largest sunflowers, it is
essential to sow seed directly into the garden, rather than start
them in pots. This is because sunflowers have long taproots that
grow quickly and become stunted if confined.
To sow seeds, water your soil, and
press seeds 1” deep about 6-8” apart. Put
snail bait in a circle around the clump if snails are a problem and
cover loosely with netting to protect emerging seedlings from birds.
If the soil is kept moist, seedlings will appear within 5-10 days.
When the plants grow to 3”, thin them to the most vigorous 3 or 4.
When they are a foot tall, thin them to 2, and when they reach 2
feet high, select the best, most vigorous candidate. The point of
this gradual thinning method is to ensure that you’re left with at
least one good seedling in the event that predators damage any of
the others. Remember, it's critical to thin back to the best single
seedling if you're going for giant sunflowers. Leaving even several
seedlings growing too close together will keep you from growing a
giant in your garden.
Water and Feeding
Feed often and water regularly. While the plant is
small, water around the root zone, about 3-4” from the plant with
about 2 gallons of properly diluted liquid fertilizer solution per
week. For larger plants, scrape out a small doughnut-shaped moat
about 18 inches around the plant and about four inches deep. Pour
several gallons of properly diluted fertilizer into the moat every
week. Sunflower roots can grow to 4 feet below the soil surface.
Avoid pouring fertilizer directly on the stems, since this can cause
them to rot.
Another feeding method for larger
plants is to make several holes by driving a steel stake into the
ground about 3-4 feet deep and about 1½ feet from the plant. Fill
the holes with properly diluted liquid fertilizer. Woodland plant
geneticist Tom Heaton uses Miracle
Grow or Schulz’s growing solution. Organic gardeners may want to use properly diluted fish emulsion or other liquid organic
Be attentive to weather
reports, especially, as your plants become taller and more
top-heavy. When heavy winds are predicted, delay watering to reduce
their chances of blowing over. Staking isn’t usually necessary for
sunflowers, but it can be helpful when it's extremely windy or if
they must be grown in conditions that are too crowded or in too much