Gladioli are often planted in the garden because of the colorful diversity of varieties and the characteristic flowers. The ornamental plants are sun worshipers that are persistent in Central Europe, but cannot be left in the bed over the winter. The tubers must be dug up and stored in suitable places before the onset of winter. Overwintering outdoors is attractive to many gardeners because of the high amount of work involved. Now the question arises: Can you overwinter gladioli outside?
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Is it possible to hibernate gladioli outdoors?
Gladioli have a permanent place in numerous gardens because of their abundance of flowers, which is particularly evident in the varieties. Despite the easy-care species, a great deal of effort is required as soon as winter comes. At temperatures below 4°C, the tubers of the iris family (bot. Iridaceae) can no longer be stored outdoors and have to be laboriously extracted from the ground and stored in a warm place. Depending on the size of the bed, this work can take a lot of time. Many gardeners wonder if it is possible to store gladioli outside over the winter. Fortunately, the tubers can overwinter outside as long as the following points are observed:
- hardy gladiolus used
- Winter protection available
- allows air circulation
Otherwise nothing stands in the way of wintering outdoors. The preparation is much easier as long as you have planted the right gladioli. Classic varieties and species are not suitable for this, especially those that produce a lot of flowers. Once winter arrives, they are simply too weak to withstand the temperatures.
Hardy gladioli
As already explained in the previous section, it is above all the hardy Gladiolus varieties that are suitable for overwintering outdoors. You have the choice of a manageable number of varieties, which are mainly bred from these two species:
- Gladiolus nanus
- Gladiolus primulinus
Most of the commercially available dwarf gladioli are cultivated from these. Due to their properties, they are much more suitable for wintering outside than their larger relatives. The following characteristics are the reason for the better frost hardiness, which makes it possible to overwinter the tubers outdoors:
- small-flowered
- earlier heyday
- generally more robust
Dwarf gladioli use significantly less energy to flower and have more time left until winter, making the bulbs more resilient to winter and cool temperatures. For this very reason, they are suitable for overwintering, even down to temperatures of -20°C to -25°C. Of course, they need winter protection, but moving indoors is not necessary. You can use the following five varieties:
- Dwarf Gladiolus ‘Galaxian’
- Dwarf Gladiolus ‘Vulcano’
- Cottage-Gladiole ‚Claudia‘
- Dwarf Gladiolus ‘Las Vegas’
- Dwarf Gladiolus ‘Elvira’
Of course, there are other dwarf gladioli that are “hardy”. Just look around a bit, because there are always new varieties being introduced by breeders. As an alternative to the hardy gladioli, you can use native species that naturally overwinter in the ground. This includes:
- Marsh gladiolus (bot. Gladiolus palustris)
- Meadow gladiolus (bot. Gladiolus imbricatus)
Due to the significantly lower amount of flowers, the native representatives are rarely cultivated in the garden. If you prefer much harder plants, you should use these species.
Overwintering gladioli outside: instructions
Overwintering gladioli is largely done by the plants themselves if they are hardy. However, since they are delicate plants, they need some support to keep from freezing to death or rotting. For this reason, they receive winter protection that protects against the cold and provides the tubers with sufficient fresh air. If the tubers do not get enough fresh oxygen during the cold season, they will rot and will not bloom in spring. A winter shelter made of the following materials is used to allow the gladioli to get enough air:
- compost (not fully rotted)
- Reisigzweige
- foliage (dry)
Timing is important when applying. As soon as the temperatures drop below 4°C or the first night frosts appear, take care of the winter protection. Simply apply a layer of one of the materials mentioned. Make sure it’s not too dense, especially if you’re using the compost. The layer should not be too thin so that moisture and cold do not penetrate inside. More effort is no longer necessary, because next year the tubers will hopefully sprout again by themselves. The above-ground parts of the plant will die off over the winter. You can remove these before applying the winter protection so that the tubers can still gather a little energy for the coming season.
