Chrysanthemums are among the most beautiful autumn plants. But what happens to the flowers after the blooming period ends? Can they overwinter outdoors or are they not frost hardy? We take a closer look at the question and explain which chrysanthemums are hardy and how you can recognize them.
Chrysanthemums belong to the family “Asteraceae”. These beautiful flowers are actually native to Asia and grow best in regions with a mild climate such as the southern parts of China and India. They were brought to Europe 3 centuries ago. Nowadays there are various varieties that decorate the home garden and balcony. However, most varieties are not winter hardy. We take a closer look at the different variants.
Chrysanthemum hybrids in pots are not frost hardy
You can find various small-growing varieties of chrysanthemums in garden centers. Most hybrids are specifically bred as annual plants and are not frost hardy. If you bought fully grown plants in full bloom in the fall, then they are most likelythe autumn chrysanthemums. They are brought to garden centers in the summer and are then available from September. Normally, flower formation is promoted by regularly removing the wilted plants. With good care and a warm autumn, this can extend into November. After the permanent frost sets in, the hybrids die. However, it is possible to overwinter indoors, but flower production will decrease over the next few years.
The winter asters can spend the winter outside
In contrast to other autumn-flowering chrysanthemum varieties, which have a compact growth and are grown as low flowers in pots, winter asters are perennials with a spreading habit and a maximum height of one meter. The winter asters are mainly available as young plants in nursery pots. You can buy these in the spring, just before planting out. However, it makes much more sense to purchase them in the fall - then the flowering perennials don't have to spend the winter in a warehouse.
The winter asters are considered hardy. However, the young plants are still somewhat sensitive to frost. You can spend the warm autumn months - September and October on the balcony or terrace. However, you must place the pots on a Styrofoam base so that the roots do not freeze overnight and wrap the pots with fleece.
Are garden chrysanthemums hardy?
You must overwinter them in an unheated room or greenhouse by November at the latest, but before the first night frost. The temperature in the winter quarters should definitely be below 7 degrees Celsius, otherwise new shoots will be encouraged. Young shoots are particularly sensitive to frost and will freeze when planted out in spring, which will of course negatively affect the growth of the plant. However, if the room temperature remains below 7 degrees Celsius, the plant will not sprout again.
The garden chrysanthemums are planted in the garden in spring and then develop their root system in the summer months. The flowering period can vary greatly from variety to variety, but for most it begins at the end of August / beginning of September and ends around November / December.
So if you planted chrysanthemums in the bed in spring, then they are the winter-hardy species. However, you have to prepare the perennials for the coming winter in autumn. To do this, do the following:
- During the flowering period, pick off the dead flowers regularly (ideally once a week).
- After the end of the flowering period, the above-ground parts of the plant dry out and the leaves and shoots turn brown. Then it's the right time to make a caring cut.
- The shoots shortened to a quarter of their length. Sickly shoots are completely removed. The plants are also raisedPests and diseaseschecked and, if necessary, treated before cutting.
- To protect the sensitive roots from frost, the flower bed is mulched with pine brushwood.
Don't confuse autumn asters and chrysanthemums!
Before you consider how to get your chrysanthemums through the winter, you should be sure that the flowers in the bed are actually chrysanthemums. All too often, autumn asters and chrysanthemums are confused. No wonder, because the two plant species are closely related and look very similar. However, they are hardy to different degrees.
- Autumn chrysanthemums in pots are not hardy. They are grown as annual flowers and are rarely overwintered indoors.
- Winter asters or garden chrysanthemums are hardy, but must be cut back in late autumn and need additional frost protection with mulch in the winter months.
- The autumn asters are very hardy and can easily withstand temperatures of up to -40 degrees Celsius. Wind, rain and snow don't affect them. The flowers are therefore not cut back after the end of the flowering period. Even more so - the shoots should definitely be left standing because they protect the roots from frost and cold.
How to recognize the autumn asters: They bloom before the garden chrysanthemums. If the flowers in the pot on the balcony or in the bed have already bloomed in mid-October, then they are probably autumn asters. However, if they only start to bloom or are in full bloom in mid-October, then they are probably garden chrysanthemums.
Also read:Which potted plants can tolerate frost? These three will add magic to your balcony or garden!
