They do not re-grow and blossom. These are the cultivars that are often grown for their big size, gorgeous flower heads, and delicious seeds. However, certain species of sunflowers may be cultivated as perennials, which means they will bloom again the following season. While this is possible with many different types of plants, it is not easy or common practice with sunflowers.
As far as we know, only two types of plants produce seed that can germinate and grow into new sunflowers: seeds from a single flower (monoecious) or pollen from one species on pistils of another species (polycecious). Since sunflower plants are self-pollinating, this means they must cross-pollinate to produce offspring.
Most sunflower varieties are bred to be attractive garden flowers that last for several weeks in the summer. They tend to have large, showy yellow or orange petals and a large, showy head full of these flowers. But most sunflower seeds don't yield plants that match the beauty of the parent plant. Only some of the largest-seeded varieties get picked for their seeds. The rest are discarded when the pods reach maturity.
In fact, most commercial varieties of sunflowers were developed to use their seeds rather than their flowers. The best known sunflower with its seed used for food is probably Canola oil.
Annual sunflowers die after forming flower heads and go to seed. These include American sunflower (Helianthus annuus), Portuguese sunflower (H. pannonicus), and Siberian sunflower (H. angustifolius).
While most sunflowers used for decoration go out of season when they stop flowering, some types are designed to remain in bloom all year long. These include 'Mickey Mouse' sunflower and 'Sugar Ears', which have large ears of yellow flowers surrounded by dark green foliage.
Sunflowers use photosynthesis to convert sunlight into chemical energy that plants use to produce food. The color of the petals and the size of the head are important factors in determining how much oil the plant will produce. Large-headed varieties such as 'Cosmic' and 'Imperial' can yield up to 20 gallons of oil per square yard.
The flavor of sunflower seeds is very similar to that of pumpkin seeds. They both have a mild taste that some people say tastes like chicken. However, others say they taste like nuts.
If the sunflower variety is a perennial, it will return and bloom the following year. Every year, annual varieties must be replanted. Sunflowers will also regrow if they are self-germinating, meaning they grow from seeds that fall off the plant, if the heads are left on in the winter. The plants will die back down to the ground but will come up again next season.
However, this process won't help increase the flower's size or number of flowers. If you want to grow bigger flowers or more flowers, you'll need to select for those traits when you select your seed stock. It may be possible to grow larger flowers by adding weight to the stem just above the head. This can be done by tying strings around the stems of large plants or taping heavy objects to them.
Some people claim they have success growing larger flowers by wrapping string around small plants and then removing the strings after flowering. However, there is no guarantee that these plants will produce larger seeds or even live long enough to reproduce. You should try this method on a trial basis with low-growing varieties first, because it is not recommended for growing flowers in water-restricted areas.
The best way to grow larger flowers is to select for larger plants when you select your seed stock. Larger plants will have more room to grow and develop into larger flowers without breaking off below the soil line.
Sunflowers are propagated from seed. They are sown in the spring and harvested in the fall, like do other crops. A seed starts and ends its life cycle. The seed is planted, germinates, matures, and eventually blooms. After flowering, the seed head will gradually turn brown and die.
The lifecycle of a sunflower begins with the sprouting of the seed. The seedling grows rapidly for about two weeks before becoming a stem with leaves. From this point on, the stem continues to grow until it reaches around 15 inches (38 cm) high. At this stage, the stem begins to bend over, forming a head at the end that will contain hundreds of tiny yellow or white flowers. The flower head may be as large as 18 inches (46 cm) across. As the head matures, the individual flowers turn brown and drop off the stem. New flowers will develop next year from the seed stored inside the head.
This seasonal plant needs sunlight and adequate water to survive. It prefers well-drained soil with some organic matter in the form of manure or compost. If it does not get enough light, its stem will become spindly and thin.
Sunflowers are used for food and oil. The seeds can be eaten either roasted or boiled, and they have a nutty flavor.
The majority of sunflowers are annuals, which means they only live for one year and must be transplanted the following year. Of course, depending on the sunflower type, you may obtain fewer seeds or smaller blossoms. The hubbard sunflower is a perennial that lives for two years or more in warmer climates. It can be maintained by dividing the root ball every other year.
During its first year, a sunflower produces a large head of yellow flowers that contain about 20 percent oil. This oil is used for fuel and cooking purposes. The remaining 80 percent is made up of protein, carbohydrate, and some minerals. Sunflower seed oil is very high in linoleic acid and contains few saturated fats. It is also an excellent source of vitamin E, phosphorus, magnesium, and potassium.
As it matures, each head grows larger who's shape is determined by the weather during flowering time. In warm temperatures, the heads are round while in cold conditions they become flat.
After its first season, when the plant reaches maturity, the energy stored in the root system begins to decay after which time the plant will not grow anymore. However, if the plant is kept through winter dormancy, then growth will resume the next spring.
The lifespan of a sunflower depends on how long you can keep them alive.