When Do Sunflower Plants Bloom?

Bloom Time

• To allow themselves time to reach such towering heights, sunflowers generally bloom within two months of seed planting, with full maturity coming about a month later. Blooming starts with the long stem, followed by large, rough-textured leaves and finally the characteristic vibrant yellow and deep black flower head. You will know the flower is completely mature when its head turns down to face the ground; this isn't wilting but rather a defense mechanism to make it harder for birds to eat the sunflower's seeds.

Planting Time

• Now that you know how long sunflowers take to bloom, you can decide on a planting time. You can plant sunflowers as soon as nighttime temperatures in your area are holding steadily above 50 degrees Fahrenheit, generally in late spring. This will allow the sunflowers optimal time to reach their full heights. You can sow sunflower seeds anytime after that point as well, but they will not have as much time to grow to their tallest potential. You should always start sunflowers outdoors instead of in pots, since they spread long, thick roots needed to support their colossal height.

Planting Conditions

• Plant sunflowers in an outdoor area that receives at least six hours of sunlight per day; they will thrive in up to eight hours of full sunlight daily. Mix in a slow-release fertilizer, as well as a drainage agent such as aged compost or manure 8 inches deep into your soil before sowing seeds. Because they sprout so quickly, the sunflowers will use up nutrients and moisture in the soil soon after germinating. Space seeds about 20 inches apart for ideal growing room.

Care

• Water the soil just before you plant so that it is uniformly moist, and keep it that way for at least two weeks after planting to aid in germination. Once the plant begins to grow, water with diluted liquid fertilizer at least once per week; by the time they are about 3 feet high, they can use 4 to 5 gallons of diluted fertilizer and water each week. Be sure to follow dilution instructions of your chosen fertilizer. If it is not time to feed but the top 2 inches of soil feel dry to the touch, water with regular water.