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Rosemary has been an integral part of German kitchens for many years. The Mediterranean kitchen herb can also be found more and more often in German gardens or on the balcony or terrace. As a Mediterranean plant, rosemary does not tolerate our cold winter temperatures well or at all. Nevertheless, the following applies to overwintering: rosemary is not just rosemary, it depends on the variety.
Botanical assignment and origin
The popular culinary herb, botanically Rosmarinus officinalis, is one of two species in the genus Rosmarinus. In botany, the following subspecies are distinguished.
- Rosmarinus officinalis subsp. officinalis
- Rosmarinus officinalis subsp. palaui
- Rosmarinus officinalis subsp. valentine
All species are mainly found in the western and central Mediterranean. The plant has been cultivated in the eastern Mediterranean and on the Black Sea since ancient times. The herb was first mentioned in Central Europe in the 9th century.
Rosemary is one of the perennial plants. Depending on consumption (harvest), location and care, it can be a companion for a number of years. How it survives our winters best depends on the variety. Basically, rosemary can be divided into three overwintering groups.
- (conditionally) hardy varieties
- hardy varieties
- neither hardy nor winter hardy varieties (sensitive varieties)
Tip: No matter what variety rosemary belongs to, it should not be fertilized in winter.
Hardy or hardy?
When it comes to the overwintering of plants, the two terms "winterproof" and "hardy" appear again and again, also with rosemary. Although both terms suggest frost resistance, only hardy plants survive the German winter outdoors.Rosemary, Rosmarinus officinalis
For the hibernation of the rosemary this means:
- only a few hardy varieties
- many hardy varieties
Hardy and hardy varieties
Since there are only a few really hardy varieties, you should use the varieties as a guide when buying. Hardy varieties include the following.
- Veitshöchheim rosemary (special breeding for German conditions)
- Blue Winter (down to minus 20 degrees Celsius)
- Arp (extremely resistant to frost)
- Hill Hardy (conditionally hardy, needs protection)
Tip: If rosemary comes out of a pot from the supermarket, it is in most cases a non-hardy variety. It is better to buy hardy rosemary from a nursery.Rosemary, Rosmarinus officinalis
hardy Varieties withstand cold spells between minus 15 and minus 22 degrees Celsius, depending on the variety. winter festivals Varieties tolerate temperatures around freezing point. If the sub-zero temperatures fall into the single-digit range, they already need appropriate protection.
Tip: Hardy varieties should only spend the winter outside in the German wine-growing regions or in the mild climate zones with a cold protection of leaves and brushwood. In all other areas they should overwinter in the pot at 10 degrees Celsius.
Under no circumstances should it be harvested during the winter. The harvest time ends in mid-August, as cold can penetrate through the interfaces.Rosemary, Rosmarinus officinalis
location and other criteria
To ensure that rosemary survives the cold season well, other criteria must be considered in addition to the variety.
During the winter neither the branches nor the roots of the plants should freeze. Rosemary also needs a lot of sun in winter. Ideal locations for the rosemary are as follows.
- full sun south
- in front of walls or house walls (radiate heat)
Young rosemary is far more sensitive to frost and cold than older plants. Only from the age of three years, when the plant is deeply rooted in the ground, can it survive the cold season well.
Therefore, young plants like hardy rosemary varieties should:
- overwinter in the pot
- Frost free
- at temperatures around 10 degrees Celsius
Tip: Older plants are happy about a cold protection from brushwood and leaves. Make sure there is sufficient air circulation, because rosemary does not tolerate high humidity.
In the pot
Overwinter in the pot
Of course, hardy rosemary can also be grown in pots. With the appropriate protection, the plants can even overwinter outdoors in a sheltered location. However, he then does not tolerate a change of location between inside and outside. If you have taken him inside out of concern, he should be allowed to stay inside. Because he is then used to the warmer temperatures in the house and can no longer cope with the cold temperatures outside.
One of the most important measures for wintering outdoors is protection against:
- wet and cold
Although rosemary is a sun-worshipper, strong sunlight in winter is not good for it, because then a lot of water evaporates through the leaves. If it doesn't get water, it dries up.
wet and cold
To prevent moisture and cold from penetrating, you should protect rosemary from below and above.
For protection “from below” bodies:
- the pot in winter
- on a styrofoam mat or
- a thick plank of wood
So cold and wet cannot penetrate. Also make sure that the pot does not freeze solid to the bottom. For protection "from above", cover the soil with leaves or brushwood, because too much moisture can lead to rot in the root area and subsequently to the death of the plant.
Tip: When covering, make sure there is sufficient air circulation so that no rotting organisms can settle.
If heavy or continuous rain is announced, the plant must be additionally protected from moisture with a frame plus tarpaulin. A small canopy on the balcony or terrace is also good protection against rain. For large plants, you should also protect the branches. This works best when the plants "get under the hood".
The following are suitable as hoods:
- jute covers
- synthetic fleece
- fixed bamboo mats
- coconut carpets
Winter care in the pot
Although rosemary should be protected from moisture when overwintered in a pot outdoors, it does need to be watered from time to time.
- low watering
- Plant must not dry out
- Avoid waterlogging
If the rosemary has "got under the hood", it must be removed regularly on frost-free days to air it out.
Tip: Aerating is also an opportunity to inspect the plant for frost damage.
beginning of spring
end of hibernation
If the spring temperature rises permanently above zero degrees Celsius again, the winter protection can be removed. For rosemaries that have overwintered under the hood, you should initially only remove the hood for a few hours so that the plant can get used to the new climatic conditions again.
Rosemary sensitive to cold and frost
While hardy and, depending on the region, hardy rosemary can overwinter outdoors, many varieties, including "Salem" or "Pine Rosemary" do not survive the German winter outdoors. They're not even winterized. That is why they are also cultivated in pots.
Since all rosemary varieties love the sun, varieties that are sensitive to cold should also be kept outside during the summer. Cultivation as a pure houseplant is not recommended, since most apartments, even bright ones, are too dark for the plant. That is why the window sill is not an ideal location in summer.Rosemary, Rosmarinus officinalis
The ideal winter quarters for potted rosemary:
- is light
- has a temperature between 4 and 12 degrees Celsius
Examples of suitable locations are:
- garden or greenhouse
- bright basement
- little heated bedroom
Tip: If the winter is mild, pot rosemary can also hibernate outdoors. However, the pot must then be wrapped in protective film and the plant protected with brushwood.