How Long Do Sunflowers Bloom?

What are the Stages of Sunflower Development? How long is the Vegetative and Reproductive Phase? When and How Long do Sunflowers Bloom? What is the Pollination Phase?
how long do sunflowers bloom

Sunflowers are tall and strong plants with beautiful and vibrant flowers. Sunflowers are sun lovers and their blooming season generally starts in mid-summer. Depending upon their type and growing conditions, the blooming of their flowers may vary. You must have wondered how long do sunflowers bloom and when do sunflowers bloom? In this article, we will be covering that and much more about sunflowers. 

1. What are the Stages of Sunflower Development?

Field of tall sunflowers: how long do sunflowers bloom 1

Every plant goes through various stages in its lifespan, from germination to its eventual death. Similarly, the sunflower also goes through five stages during its life cycle. These stages can be divided into,

  • Germination phase,
  • Vegetative phase,
  • Reproductive phase,
  • Blooming phase,
  • Harvesting phase. (See What is a Toadstool?)

2. What happens in the Germination Phase?

A man sowing the seeds.

This is the first phase of sunflower plant life. It begins when you plant the seeds and lasts up to eight days. In sunflowers, germination takes place from mid-April to late May, but this may vary based on when you plant the seeds. In this phase, the root and shoot system of the seeds starts developing rapidly. The shoots pop out of the soil and wait for sunlight to start the process of photosynthesis. (See How to Grow Purple Sunflowers?)

3. How Long is the Vegetative Phase?

The vegetative phase begins after the end of the germination phase. Around the 13th day of planting the seeds, you will notice that the plant is still a seedling. The period when the new shoot system is developing is known as the vegetative phase. This phase is divided into numbers depending on the growth of the plant, like vegetative phase number one or two.

  • When the plant develops its first leaf, it is vegetative phase one (V1).
  • Continuing from V1, when the plant grows two leaves that are 2 cm (about 0.79 in) in length, it is said to be in vegetative phase number 2 (V2) and this process and phases keep going.
  • Between V2 to V8 at distinct stages, several post-emergence herbicides are applied to the plant. For the seeds planted in April or May, the vegetative phase begins in May or early June. (See Does All Fruit Grow on Trees?)

4. What happens in the Reproductive Phase?

A new unbloomed sunflower with star-like appearance: how long do sunflowers bloom 2

In the sunflower plant, the reproductive phase begins when a bud appears in the cluster of leaves.

  • In the first stage, these buds have a star-like appearance. The reproductive phase usually begins in June and ends in July or August, depending upon the time seeds were planted.
  • These buds soon become a complete sunflower marking the end of the reproduction phase. A sunflower can take up to thirty days to reach its full bloom.
  • This phase is divided into nine stages depending on the flower’s development. Stages one to four consist of the time when the buds appear and before they start flowering.
  • In stage five, you will see several stages of flowering of a flower from the bud. Stage six marks the completion of the flowering process and stage nine is physiological maturity.
  • The harvesting phase begins after stage nine and is marked by the death of flowers and the removal of seeds. In the next segments, read about how long do sunflowers bloom. (See How to Make a Sunflower Garden?)

5. When do Sunflowers Bloom?

You need to understand blooming before you get to know how long do sunflowers bloom.

  • The blooming phase begins after the reproductive phase when the flowers have fully bloomed. 
  • They are heliotropic. The young sunflowers during their blooming phase follow the sun from east to west and they turn back towards the east when it sets down. The stems become strong enough to carry their flowers from east to west as the flower reaches its full bloom. However, a mature sunflower does not follow the direction of the sun. It permanently faces east until it dies.
  • Flowers in this phase can be put into vases, bouquets, and several other types of decorations. Yellowness developing at the back of the head of a sunflower is a sign that the seeds are ripening and the flower is about to die. (See Do Sunflowers Need Full Sun?)

6. How Long do Sunflowers Bloom?

Field of dunflowers.

The blooming phase lasts only for twenty days during which the sunflower stays alive. The time and duration of blooming vary from flower to flower. You can keep a precise record by measuring their growth weekly. The Giant Single head variety of sunflower blooms during late summer and lasts for 2 to 3 weeks. Now you know.

Small and multi-headed varieties along with perennials usually bloom at the beginning of the summer. If you regularly cut the flowers then they will keep on flowering throughout the summer. (See What Would Happen if There was No Sunlight?)

7. What is the Pollination Phase?

Close shot of the center of a sunflower and a bee doing the pollination process: how long do sunflowers bloom 3

As you how long do sunflowers bloom, now it is time for the pollination phase. Bees and other pollinators start the process of pollination and fertilization of seeds takes place during this phase.

This phase begins on day 65 and lasts up to the 85th day. The large brown center of sunflowers contains thousands of discs filled with nectar. When bees, the main pollinators, sit in the center of sunflowers to drink the nectar, these seeds get stuck in their bodies. They fly from one flower to another and the pollen gets transferred. After the pollen reaches the new flower, pollination and fertilization begin. Sunflowers, like other flowers, pollinate in two ways, self-pollination, and pollination by pollinators. But sunflowers have a safety mechanism that ensures that pollination and fertilization do not fail. (See What’s the difference between annuals and perennials?)

8. What happens in the Seed Development Phase?

After pollination, the seeds are fertilized and they start ripening. This process takes place around day 85 to day 105 but can last up to the 125th day. This is the stage when the back of the flower starts turning yellow after the flower is completely bloomed. Several birds, insects, and bugs are attracted to these ripening seeds. If you want to harvest these seeds, make sure you protect them or they will be feasted upon. (See What are the Types of Sunflower Seeds?)

9. What is the Harvesting Phase?

What happens in the seed development phase

Towards the end of the blooming phase, the petals of the sunflowers will get dry and fall off. This is the time to remove the seeds from the flower’s head.

  • The flower reaches this stage after 110 to 125 days after the seeds have been planted. In case the flower is on the plant, cut it off below the flower head.
  • Keep it in a dry container for the seeds to fall off, but not all of them will fall themselves. If the seeds were planted in May then the sunflower will dry off in mid-August.
  • In late August or early September, you can harvest the sunflower seeds from the flowers. You can replant them if you want a new batch. (See How many Seeds does a Strawberry have?)

In this article, we covered questions like how long do sunflowers bloom and when do sunflowers bloom. We hope you enjoyed learning about the fascinating world of sunflowers. (Also read 34 Medicinal Plants Worth Your Garden Space)

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