Sunflowers come from North and Central America. There are two main types. Helianthus annuus is not hardy and is therefore only kept as an annual plant. Perennial sunflowers, on the other hand, are mostly hardy and bloom in the garden for many years.
Is the sunflower hardy?
Some sunflower species, such as perennial sunflowers, are hardy and do not require winter protection. Annual sunflowers, on the other hand, are not hardy and should therefore be removed in autumn or overwintered indoors.
Annual sunflowers are not hardy
Annual sunflowers cannot survive subzero temperatures. But it's not worth overwintering them indoors, as they only thrive for one year anyway and have to be sown again the next year.
Once the sunflower blossoms have faded, the popular sunflower seeds ripen inside. In autumn you harvest the seeds or cut the flowers to dry.
The kernels can be used as bird food in winter (€15.00 on Amazon). They can also be roasted as a snack or used in the kitchen for baking. It's also worth saving a few seeds for sowing next year.
Overwintering sunflower perennials
Most sunflower perennials are hardy. Like the Jerusalem artichoke, they do not need any winter protection at all.
Cut off more sensitive varieties above the ground in autumn. If available, cover it with a layer of mature compost or pile up some leaves. In spring, remove the leaf cover so that the sun can warm the earth better.
Some perennials are not hardy. They need to be dug up in the fall and overwintered indoors. It is best if you only cultivate such varieties in pots.
- Dig up perennials
- Put in pot with garden soil
- Set up cool but frost-free
- Give some water occasionally
Do not fertilize from September onwards
You should stop fertilizing perennial sunflowers from September at the latest. The fertilizer increases the risk that the perennials will not survive the winter.
Do not sow and plant sunflowers until spring
Since annual sunflowers cannot tolerate frost at all, you can only sow them outdoors when the ground is warm enough.
You should wait until the end of May to plant early sunflowers outdoors. Before that, the risk of night frosts is still too great.
Tips & Tricks
Annual sunflowers usually only have one or a few flowers. Once these have faded, the plant's time is over. It can then be cut leaving the root in the ground.