Horned violet (Viola cornuta) is one of the most commonly bought plants. It can be found as a flowering grave decoration, adorns public green spaces and is often planted as a low bedding plant in front gardens, for example. The plants present themselves in a lush variety of colors, ranging from white to a dark red or blue. The plants survive cool temperatures and frost. But the question still arises as to whether horned violets are hardy?
Are horned violets hardy?
Outdoors, the plants tolerate cold temperatures of up to -15°C without any problems. Up to these temperatures, they usually do not need special protection. They often even bloom again after a short period of frost when the temperatures rise again a little.
In winter, the leaves of the horned violets usually turn reddish, which means they can protect themselves better and the effort involved in preserving the leaves is also lower. In principle, this reddish color does not harm them - on the contrary, it is a sign that the plants are preparing well for the low temperatures.
Die off despite winter hardiness
Although the horned violet is hardy, it still happens again and again that the plants die off over the winter. However, the reason for this is not the frost, but side effects due to the cold. Only at temperatures below -15°C are the plants no longer hardy and can, but not always necessarily, die.
A common reason why the horned violet dies at significantly warmer temperatures is too much or too little water. Especially when the ground is frozen, moisture can no longer penetrate deep enough into the ground. It is similar when there is a downpour on frozen ground, because in this case the water cannot seep away quickly enough and the plants literally rot.
Another reason why the pansy does not survive the winter is that the plant is over-aged. In this case, a strong pruning in early autumn usually helps. In this case, gardeners must not be too hesitant. Even if the plant blooms beautifully and luxuriantly in autumn, every blossom and every leaf costs it unnecessary energy. Only a radical pruning favors new shoots in the next spring and the plant gets through the winter well.
Plant in time
So that horned violets get through the winter well, timely planting is important. The plants must be in the ground by early autumn at the latest. This is the only way they have a chance to take root and be strengthened for the cool season. Good soil preparation is also important for this:
- Loosen garden soil
- Incorporate compost
- Work in long-term fertilizer (horn shavings).
- work additional sand into heavy soils
The soil should be rich in nutrients but permeable to water. Garden soil can also be mixed with compost in pot culture. To prevent waterlogging, clay granules can be used as the bottom layer for drainage.
If horned violets are sown directly, they can be sown all year round if the ground is frost-free. In order for the plants to get through the winter well again, this should be started in spring at the latest.
tip: If the horned violets are isolated, the competition is not so strong and they develop into vigorous plants. The plants should be separated by September at the latest so that they can take root well in the soil.
winter protection
With a culture in the bed, winter protection is usually hardly necessary, since the horned violets are hardy to -15°C. It only becomes dangerous for them when they are planted on graves or in pots. Above all, there is a great risk that the sensitive, fine roots will be damaged. On beds or graves it is sufficient if the pansies are covered with a layer of fir twigs. It is important that the branches do not lie firmly on the plants.
Horned violets in pot culture need special protection:
- Cover the pot with fir branches or fleece
- Wrap the pot with a layer of cardboard
- Elevated placement of the pot so that water can run off
tip: Bubble wrap, which is often used as packaging material, is very suitable for wrapping pots and protecting them from frost.
Horned violets overwinter
Although the horned violet is hardy, it sometimes makes more sense to overwinter the plants in sheltered areas in very harsh locations. Plants in pot culture in particular can be overwintered frost-free. The winter storage should look like this:
- Temperature: maximum 10°C
- Humidity: medium (damp basements are unsuitable)
- light: bright
- regular air exchange
In their winter storage, you must keep the horned violets constantly moist, but the soil must not be dripping wet. In this case it can happen that leaves lying directly on the ground start to get mouldy. Before the pansies go into winter storage, they still need a cut. Blossoms and older leaves, especially those close to the ground, must be removed.
Overwintering in frost-free rooms, although Viola cornuta is hardy, has the advantage that the plants are stronger in spring and produce the first flowers faster.
notice: Despite the possibility of overwintering them in sheltered rooms, horned violets are not suitable as indoor plants. The high temperatures and the significantly reduced daylight cause them stress and they usually die after a few weeks in warm indoor rooms.
You should regularly check the pansies for pest infestation in their winter storage. Aphids in particular can become a problem. In this case, you can put the plants outside for a short time on frost-free days. As a result, the aphids usually flee quickly because the temperatures are still too cool for them.