With their large, bright yellow flowers, sunflowers are a real eye-catcher in any garden. No wonder, then, that they can be found in more and more gardens. The annual plants have to be sown from new ones every year. Of course, this raises the question of the right time to sow the sunflowers. As is so often the case with gardening, the answer to this depends on the weather and temperatures.
Helianthus annuus
The botanical name of the sunflower already makes it clear: it only flowers for a single year. This means: Sunflowers develop from seed to finished, flowering and fruit-bearing plant within one growing season. Their lifetime usually ends in late autumn. It does not tolerate frost and is generally very sensitive to sub-zero temperatures.
Normally a sunflower is discarded at the end of the growing season as it would not survive the winter anyway. It is therefore not possible to make a sunflower bloom again the following year. If you want to have the beautiful plants in your garden permanently, you cannot avoid sowing them again every year.
Sowing the sunflower
Sunflower seed is either bought from a garden supply store or you can use the seed collected from the previous year's plant. On the one hand, it is possible to prefer the sunflowers indoors and then transplant the young plants outdoors a few weeks later. The advantage of this approach is that the plant is more likely to start flowering earlier. On the other hand, sowing can also be done directly outdoors and at the later location. Which method you choose depends largely on your personal sensitivities.
Notice: Sowing in a protected room (apartment) takes place in a planting bowl and should take place around the beginning of March. The young plants may only be transplanted outdoors when they are strong enough and there is no longer any frost outside.
time
As already mentioned, Helianthus annuus is very sensitive to sub-zero temperatures. This affects both the finished plant and its seeds. The sunflowers may therefore only be sown outdoors when no more frost or ground frost is to be expected. This is usually the case in our latitudes at the end of April/beginning of May. Around this time, early young plants should also be placed outdoors. With an earlier date, the risk is too great that the plant will freeze to death or the seed will not germinate in the soil and then rot. A later date, on the other hand, means that the sunflower blooms later and shorter.
Exception perennial sunflowers
A sunflower is not just a sunflower. Basically, you have to distinguish between two types. Everything that has been said so far refers to the annual sunflower, namely Helianthus annuus, which has long since become the epitome of the sunflower in our gardens. In addition, however, there are other species with the perennial sunflowers, which are somewhat smaller in growth. Typical species are Helianthus atrorubens, Helianthus decapetalus or Helianthus tuberosus.
What all these species have in common is that they are perennial and therefore also hardy. The annual recurring sowing is of course not necessary for them. Instead, the plants overwinter outdoors and start growing again in the spring. Incidentally, when sowing perennial sunflowers for the first time, a time when no more frost is to be expected is also recommended.