How hardy are asters in the garden and in pots? 6 hardy varieties

Asters are nature’s last blooming gift. Its shoots have risen from the earth almost unnoticed and are now shining in bright colors. Their stamina lasts all autumn, only the frost sets a natural limit for them. Then the same applies to the asters: The season is over! They are armed against the cold, only some specimens need a little help.

Winter hardy varieties

Winter hardiness is an important prerequisite for every plant to survive freezing temperatures outdoors without damage. A distinction is made between different types of winter hardiness, as not every plant can withstand the same amount of cold. With asters, however, you can rest assured that they are tough on this.

  • -23 degrees Celsius is the tolerance limit of wild asters
  • Bergastern tolerate temperatures down to – 28 degrees Celsius
  • Alpine asters and pillow asters survive down to – 40 degrees Celsius
  • Robust and smooth leaf asters can even withstand – 45 degrees Celsius
  • only so-called summer asters are an exception
  • they are not winter-proof

Sensible winter protection

Although the asters are hardy in winter, it can be advisable to protect them specifically in winter. Especially when the following factors are given:

  • the plant is one of the more sensitive varieties
  • the aster grows in the pot
  • the region has a harsh climate
  • there are long and heavy frosts
Tip: The freezing cold is not just about survival. It also tears at the plant’s strength. It therefore doesn’t hurt to include every aster in the winter protection measures if possible.

Root coverage

The aboveground plant parts of the aster die on frosty days. It is not necessary to protect them. Fresh shoots develop in spring and bloom in autumn. What is worth protecting in winter lies underground: the roots. So that the frost cannot penetrate them with full force, a thick cover made of the natural materials listed below should be placed over them.

  • dry foliage
  • Rindenmulch
  • Compost
  • brushwood
  • as well as fir branches
Tip: It doesn’t hurt to combine several covers at the same time. For example, compost can first be piled up in the root area and then covered with fir branches.

No pruning in autumn

In the fall, secateurs are often used routinely for dry parts of the plant. Granted, the bare stalks of the aster don’t exactly look delightful. From a purely visual point of view, their disappearance is not a big loss, and the garden also looks nicely tidy. But with asters it would be more appropriate to postpone the pruning to spring. The dry plant material is like a protective cloak for the perennial. It softens the cold and keeps the moisture within limits.

  • do without the autumn pruning
  • do not prune back near the ground until March
Tip:  In autumn, however, you should remove all dried-up flowers, as they tend to rot in high humidity.

Top fasters

Top fasters are hardy and can overwinter outside. But their home, the bucket, poses a special challenge. When there is frost in the air, the pot comes into contact with it from all sides. There is a risk that the potting soil will freeze through.

  • good winter location is crucial
  • it should be light, cool and sheltered from the wind
  • warm house wall is ideal
  • let old shoots stand until spring
  • do not fertilize
  • occasionally water something if the place is covered
  • do not overwinter in warm rooms
Tip: Wrap the pot in addition with fleece or jute. This isolates and thus significantly reduces the damaging effects of the cold.

The aster varieties that are planted are usually sufficiently hardy to defy the icy temperatures in this country on their own. Top fasters, however, freeze faster and depend on our protection. But a warm winter dress is easy to put on. Compared to the joy that the long-lasting flowers of the asters spread, the manageable amount of work is definitely worth it.

Kira Bellingham

I'm a homes writer and editor with more than 20 years' experience in publishing. I have worked across many titles, including Ideal Home and, of course, Homes & Gardens. My day job is as Chief Group Sub Editor across the homes and interiors titles in the group. This has given me broad experience in interiors advice on just about every subject. I'm obsessed with interiors and delighted to be part of the Homes & Gardens team.

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