Table of contents
- lifespan
- Hardiness of cosmos flowers
- Exceptions: “perennial” tubers
- "Perennial" by seed
- frequently asked Questions
Cosmos flowers are very popular because of their large flowers and their edibility and long flowering period. But are cosmos flowers hardy and perennial? Everything you need to know about this can be found in the guide.
lifespan
In Central Europe they apply Cosmos bipinnatus (Cosmos bipinnatus) as annual flowering plants that flower until the first frost and freeze and die as a result. Theoretically, they should be sowed or planted again in the following year. However, there are exceptions and a "trick" how hobby gardeners can enjoy a Cosmea or Cosmee for several years. The varieties play a decisive role, but also the respective region in relation to the usual winter cold.
Hardiness of cosmos flowers
In principle, every ornamental basket falls under the non-hardy plants and thus under the annual plants. They belong to hardiness zone 8 to 11. Central Europe mostly has winter hardiness zones between 6 and 7. This means that for large parts of Germany the ornamental cosmos is not sufficiently hardy and would die off outdoors. With hardiness zone 8, it can tolerate a maximum of minus 12 degrees Celsius, but this requires reliable protection against the cold and a location within a milder region. These include, for example, the following with the winter hardiness zones 8a or 8b:
- Sylt
- Hamburg
- keel
- Eat
- Luedenscheid
- Dusseldorf
- Mainz
A notice:
As soon as the temperature drops below 15 degrees Celsius, a cosmea loses its flowers and dies.
Exceptions: “perennial” tubers
Perennial are some varieties that form tuberous roots that can survive the winter. The hibernation works with these similar to dahlias. These include the following varieties:
- Chocolate Cosmee (Cosmea atrosanguineus)
- Flamingo Cosmee (Cosmos peucedanifolia 'Flamingo')
- Yellow Sulfur Cosmee (Cosmos sulphureus)
For the overwintering of the root tubers, proceed as follows:
- Dig up the root bulb after the flowers have withered and before the first frost
- suitable winter quarters: Ambient temperature frost-free around 5 degrees Celsius and dark
- no winter care required
- Plant back into the bed from Eisheiligen in mid-May
- Cut back potted plants and move to winter quarters (do not dig up)
- Winter care in the bucket: water occasionally; no fertilizing
Tip:
If you live in a mild winter region and plant "perennial" cosmos plants, you can also use the mother plants entirely Cut back, leave the tubers in the bed and cover them thickly with a cold protection such as mulch, straw, leaves or brushwood cover.
"Perennial" by seed
In order to be able to enjoy its ornamental cosmos for several years even without a root tuber and thus one-year-old specimens in the following years, new plants can be grown from their seeds. After flowering in September/October, the seeds can be recognized as spindle-shaped, dark and narrow grains. These can be removed and stored as follows and placed in the ground:
- store seeds: cool, dry and dark
- durability: two to three years
- prefer indoors or a heated greenhouse from March to April
- Sow directly into the bed or tub from mid-April
- Observe: cosmos is light germinator; Only cover seeds lightly with soil when sowing
A notice:
Seeds from a mother plant do not guarantee color uniformity. Different colored flowers can also develop on the plants.
frequently asked Questions
Cosmos flowers are not palatable to snails. They avoid them, which is why they can be described as snail-resistant.
Although cosmeen are not native plants, their flowers provide nectar and pollen, which primarily provide food for bees, but also butterflies. Therefore, the jewelry basket is a real magnet for these and many other insects. Another advantage is the long flowering period until autumn, so that they represent an equally long food source for bees & Co. when most of the other flowering plants have long since faded.
Yes, that's possible, but it doesn't bring the desired success of surviving the winter months. Once the seasonal plant has withered, it inevitably dies. The first frost only contributes to speeding up this process. It will also die without a frost, although the death will then be delayed a little. It is therefore useless to move the decorative baskets before the first frost. Only the tubers, which only form in some varieties, can overwinter.
Mandy
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