So far you thought ornamental onions were always and without exception perennials? If you're not mistaken. There are certain species and varieties that, exposed to the winter without protection, freeze to death outside.
Most ornamental onion species survive the winter in the ground without damage
Most species and varieties are hardy
Normally there is no need to worry about ornamental onions in winter. This plant is mostly hardy in our latitudes. The bulbs survive in the ground until spring and then sprout again. Most representatives of this plant genus tolerate temperatures down to -20 °C without any problems.
There are exceptions…
But like everywhere else in life, there are exceptions with ornamental onions, namely those that do not tolerate frosty temperatures as well. This includes, for example, the well-known Schubert's ornamental onion. These and a few less common species should be overwintered.
Overwinter ornamental onions - how does that work?
What you should know:
- frost-sensitive species should preferably not be cultivated outdoors
- saves a lot of procedures
- It is better to plant bulbs of non-hardy species in pots
- in pots: simply put them in in the autumn
- Overwintering quarters: cool between 5 and 10 °C
If you planted a frost-sensitive species outdoors, you can overwinter it by digging up the bulb in autumn. This is much more complex than overwintering a potted plant. Onions are cleaned and stored in crates with sand or ventilated wooden crates.
Prepare for winter
After flowering, the ornamental onion withdraws. The seeds form and the plant gradually wilts. By late autumn it has dried up. You are welcome to cut it back if it has already turned yellow. You should stop fertilizing in the summer. Further preparation measures for the winter time are not to be considered.
It may be useful to cover the area of the bulb on the surface of the earth with brushwood, for example. This prevents too much moisture from penetrating the soil, which could cause the bulb to rot.
tips
Varieties that are not sufficiently hardy but will tolerate some frost (e.g. 'Summer Drummer') should be planted deeper into the ground. There they are safer from frost.