The lavish blooms of chrysanthemums are rarely seen in the autumn garden. There is uncertainty among home gardeners as to whether chrysanthemums are hardy and therefore thrive perennial. As a result, the colorful perennials are only allowed to appear on the balcony and terrace for a short season and are then disposed of. Find out here what the winter hardiness of winter asters actually is. A tried-and-tested guide to wintering shows the conditions under which the picturesque flowers in beds, pots and in the cemetery can stand up to frost and snow.
Instructions for wintering
As the short excursion into botanical basics shows, when caring for Asian wild species you can only assume that it is a completely winter-hardy perennial. In order for the enchanting hybrids to survive the cold season in beds, balcony boxes and pots, various requirements must be observed. The following instructions explain in detail how to do it correctly.
Location quality
Wetness is the biggest enemy of hardy chrysanthemums. If waterlogging can be reliably ruled out when choosing a location, even bitter frost will not cause any problems for the plants. In the modern interpretation of the prairie garden, in the gravel bed or rock garden, the lavish magnificent perennials are in good hands. Here, permeable, loose and yet nutrient-rich soil dominates, in which rainwater can drain off quickly. The better the garden bed simulates the conditions of a North American prairie, the more effectively your chrysanthemums will be able to withstand harsh winter weather. This is what the ideal location is like:
- Sunny to off-sunny
- Ideally warm, sheltered and with a slight slope
- Loamy-sandy to sandy-humous, preferably coarse-grained soil
- Fresh to moderately dry and with good drainage
Normal, good garden soil is modified with simple tillage so that it meets the requirements. To do this, dig the bed to a depth of around 30 cm and create drainage made of gravel or chippings at the bottom. A third of a clay-based, heavy excavation should be thinned out with sand and fine-grained gravel, which also ensures good permeability. Fill this optimized garden soil over the drainage and compact it moderately with a shovel, a board or a lawn roller.
Tip:
A suitable substrate is recommended for chrysanthemums in pots and balcony boxes. High-quality potted plant soil that is enriched with quartz sand, perlite or small-grain chippings works well. A few pieces of pottery on the bottom of the vessel act as water-conducting drainage and prevent waterlogging.
Planting time
Chrysanthemums planted in autumn have little chance of a he althy overwintering. The time is far too short to root strongly enough in the bed and substrate for sufficient winter hardiness to result. However, if you choose the weeks between the end of April and the end of May as the planting time, the time window is open long enough for the perennials until winter.
Tip:
When buying your autumn chrysanthemums, ignore any plants that come from a warm greenhouse. Instead, choose varieties that the gardener lets grow in beds and fields so that they are already used to the harsh outdoor climate as young plants.
Overwintering in the bed
Chrysanthemums are fertilized for the last time when the flowering period begins in late summer or early autumn. By applying a potassium-rich fertilizer in August/September, you will support both flowering and winter hardiness. For example, Thomaskali contains valuable potassium as well as phosphorus and magnesium. In the naturally managed ornamental garden, comfrey manure fulfills this task thanks to its natural potassium content. Potassium in particular strengthens the cell walls in the tissue and lowers the freezing point of cell water. Chrysanthemum hybrids also support you with the following precautions:
- Before the first frost, pile up the root disc with autumn leaves and conifers
- Protect the plants in wind-exposed locations with translucent, breathable fleece
- Alternatively, add brushwood or pine fronds all around
Please do not cut back the perennials after the flowering period. The withered inflorescences serve as natural winter protection. Only in February or March do you cut off all shoots down to the ground to make room for fresh growth.
Flower boxes and pots need winter protection
Planted in the bed, the root ball of a chrysanthemum is well protected from the rigors of winter. The perennials do not receive this security in the comparatively small substrate volume of balcony boxes or pots. The greatest danger here comes not from frost, but from repeated changes between freezing and thawing weather. Within a short time, the cell walls in the tissue are contracted and stretched so that they can burst. This doesn't have to be the case, because you can effectively prevent winter damage with the following measures:
- Before the onset of winter, place planters in front of a house wall that is protected from wind and rain
- Place boxes and buckets on wooden blocks or Styrofoam
- Cover the vessels with bubble wrap
- Spread autumn leaves, peat or wood shavings onto the substrate
The cover is indispensable for winter protection, but not very decorative. Wrapped with jute, burlap and colorful ribbons, the film no longer catches the eye. Coconut mats have proven themselves well in gardening practice as a winter coat for plant boxes and pots that are decorated with pretty stickers.
Tip:
Pots with a diameter of less than 30 cm are, despite all protective measures, too small for overwintering on balconies and terraces. Before the first frost, move the containers to a bright winter quarter with temperatures around 5 degrees Celsius. Alternatively, simply sink the pot and chrysanthemum into the ground in a protected location and spread a thick layer of leaves over it.
Winter-hardy chrysanthemum varieties
The following hand-picked varieties will make your garden shine in wonderful, warm colors at the end of the season. Properly overwintered, as this guide recommends, the chrysanthemums repeat the autumnal blossom show every year.
Radiant Chrysanthemum 'Golden Yellow'
The classic variety with the blasted, golden yellow flowers is a popular cut flower for vases and bouquets. What is less known is that the chrysanthemum variety is perennial and hardy. In the right location, the extravagant flower competes with the sun.
- Growth height: 50 to 60 cm
- Flowering time: August until the first frost
'Poetry' (Chrysanthemum Indicum Hybride)
Floral splendor in poetic dimensions finds its way into the garden and on the balcony with this chrysanthemum variety. White ray florets frame a yellow center in three layers. With a diameter of 5 cm, the countless flowers attract everyone's attention. Although the plant is well hardy, the flowers turn slightly pink after the first frosty nights.
- Growth height: 40 to 50 cm
- Flowering time: October to December
‘Bees’ (Chrysanthemum hortorum)
With its warm, deep yellow, double flowers, this premium variety cheers us up on the first dull days of autumn. The chrysanthemum owes its stable stems and robust winter hardiness to temperatures of up to -17.7 degrees Celsius to several awards in perennial sightings and is therefore particularly recommended.
- Growth height: 60 to 80 cm
- Flowering period: September to November
‘White Bouquet’ (Chrysanthemum Indicum Hybride)
Creamy white pompom flowers and seductive scent long into autumn. These attributes characterize the picturesque perennial. Behind their romantic charm lies a good winter hardiness that only requires the precautions in this guide for overwintering. With its majestic size, this chrysanthemum is perfect for fence peeping, as it also provides a helpful support to prevent it from tipping over in strong autumn winds.
- Growth height: 90 to 120 cm
- Flowering period: September to November
'Mary Stroker' (Chrysanthemum rubellum)
The simple disc flowers shine in a warm ocher yellow and are enthusiastically swarmed by busy bumblebees, bees and butterflies. The perennials like to gather in small groups to add floral abundance to the late autumn garden.
- Growth height: 40 to 60 cm
- Flowering period: August to December
‘Clara Curtis’ (Chrysanthemum Zawadskii hybrid)
Native to Siberia and East Asia, this chrysanthemum trumps its counterparts in terms of winter hardiness. Even as a hybrid, the perennial can withstand temperatures of up to -23.3 degrees Celsius in the bed, provided it is given the location recommended in these instructions. Since 'Clara Curtis' is one of the first autumn chrysanthemums to develop its pink flowers, it is often combined with later-flowering varieties for a particularly long flowering period in the bed and on the balcony.
- Growth height: 70 cm
- Flowering period: July to September
Asian chrysanthemums are hardy
Within the diverse chrysanthemum genus, a small group of select species are characterized as being hardy. The focus is on the autumn chrysanthemum (Chrysanthemum indicum), which is native to North and South Korea as well as Taiwan and some Chinese provinces. The climate there is comparable to Central European conditions, at least in winter, so that the wild species can survive temperatures down to -20 degrees Celsius without harm. This category also includes the lesser-known Chrysanthemum rubellum and Chrysanthemum zawadskii, which bloom a few weeks earlier and have proven to be extra frost-resistant.
The garden chrysanthemum (Chrysanthemum x hortorum) emerged from the hardy autumn chrysanthemum and other East Asian parent plants. Thanks to its robust ancestral gallery, this species can also rely on stable frost resistance of up to -20 degrees Celsius.
In the course of cultivating autumn and garden chrysanthemums, additional species were crossed in to optimize the blooms. However, the lavish flower symphony of hybrids comes at the expense of winter hardiness, which weakens to -10 to -12 degrees Celsius.
In contrast, European species such as Chrysanthemum segetum, Chrysanthemum carinatum or Chrysanthemum paludosum arenot hardy. Their flowering period extends from spring to summer. Following seed formation and self-sowing, these annual flowers die.
Conclusion
The floral splendor of chrysanthemums is not limited to a short stint in the pot. Asian species and their hybrids certainly have the necessary winter hardiness to thrive in beds for several years. The focus is on Chrysanthemum indicum and Chrysanthemum hortorum, known as autumn chrysanthemum, garden chrysanthemum or winter aster. To ensure that overwintering is successful, these instructions explain important details from the ideal location and the best planting time to recommended varieties. If these premises are taken to heart, the effort required for winter protection in the bed is limited to a protective layer of leaves and, if necessary, a light and air-permeable fleece. Large flower boxes and pots are given a winter coat made of foil, decorated with colorful ribbons. Chrysanthemums in small pots prefer to move to a bright, frost-free winter quarters.
