Aromatic rosemary is one of the most popular herbs. Its botanical name is Rosmarinus officinalis and it belongs to the labiates family. The semi-shrub with needle-like leaves is a Mediterranean plant. It is predominantly found in the Mediterranean region. Since rosemary is accustomed to a sunny and warm climate, you should prepare it for the cold winter. How best to do this, we explain here.
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Winter indoors
If a particularly cold winter has been announced, it makes sense to bring the rosemary indoors. This is also true if you live in a region that is highly susceptible to frost, where temperatures drop below -10°C. If you have already had the experience of the soil in your garden freezing through to the roots, you should definitely overwinter the rosemary indoors. This is always recommended for non-hardy species and young plants – regardless of the region.
Location indoors
If you want to overwinter your rosemary in a pot indoors or outdoors, you should move it to a suitable location. In addition to unheated rooms, hallways and stairwells, a basement is also suitable under certain circumstances. The most important conditions for the choice of location are.
- cool
- 5 to 10 °C are ideal
- frost-free
- bright
Brightness is important for the following reason: rosemary is an evergreen plant and carries out photosynthesis even in the winter months. For this to run smoothly, rosemary needs plenty of light all year round.
Location outside
You can put your rosemary in a pot on the terrace or balcony under certain circumstances. In this case, you should pay attention to these points.
- Roots do not rot
- Roots do not freeze
- soil does not freeze completely
- woody branches do not freeze
Constant location
When overwintering in a pot, it is of great importance that the location remains the same throughout the winter. By this is meant that the pot is not brought from outdoors to indoors – or vice versa. The change in environmental conditions would be detrimental to the rosemary. If your plant was on the balcony for the first few weeks and you would still like to bring it indoors, you can do so as an exception. However, you should not then move it again. In the house, rosemary gets used to the higher temperatures. As a result, it is no longer as hardy. The more constant the location remains, the better.
Cold protection
Cold protection for the pot
In order for your rosemary to survive the winter well on the balcony or terrace, the pot needs cold protection. It is helpful to place the pot on a plate made of styrofoam. This way you can prevent the rosemary from getting supercooled and the bottom of the pot from freezing to the ground. Another positive effect is that the plant is thus protected from moisture from below. In addition, you can protect the plant in the pot with the following measures.
- put leaves on the soil
- put some mulch on the soil
- cover the soil with brushwood
It is important that the air permeability is still given. The protective layer should not be placed too tightly on the soil or even pressed tightly. To also protect the parts of the plant above the soil from freezing, you can cover the entire plant. However, it must also be ensured here that this protection is permeable to air.
Suitable, for example:
- Covers made of jute
- hoods made of plastic fleece
- small mats made of bamboo
- covers made of coconut
Aeration
If the rosemary in the pot is under a cover hood, you should help to ensure good ventilation. This is true even if the covers are naturally permeable to air. The covers should be removed on frost-free days. However, do not forget to put them back on the plant in time so that it is not surprised by the next frost.
Frost damage
Check for frost damage
Aeration on frost-free days is a good opportunity to inspect rosemary for damage. This will allow you to take appropriate action in a timely manner, if necessary. You should improve the cold protection or change the location if necessary. However, frost damage is also almost the only risk, as pests are very rare in winter.
Watering
During the winter dormancy rosemary needs very little water. Therefore, you should water it only rarely. However, it is important that it does not dry out completely. Ideally, you should water just enough to prevent the rosemary from drying out. Due to its origin, the Mediterranean plant can usually cope with dryness rather than wetness. You should pay attention to this when watering in winter.
- no waterlogging
- a little more when exposed to strong sunlight
- on terrace and balcony only on frost-free days
Tip: Do not forget to also water the rosemary under the protective cover on the balcony or terrace.
How to avoid waterlogging
Rosemary is very sensitive to getting too much water or waterlogging, so you should prevent it. Water only when the soil feels dry to the touch. The best way to feel this is with your fingertips. Make sure that excess water can always drain away easily. You can use a pot with holes and place it on a trivet. This is where the water can collect. Remember to remove the accumulated water at regular intervals. If your rosemary is outside in the open air, you should leave out the trivet. During a heavy rain, too much water would collect and accumulate on it.
Fertilize
Do not fertilize rosemary during the winter. Giving it additional nutrients would make the Mediterranean plant more sensitive. This would harm it in the cold season and should be avoided.
Pruning
Before or during the winter you do not need to cut the rosemary. Then it needs all its strength to overwinter. Pruning of the Mediterranean plant is recommended only in the spring. You can cut back the rosemary to 10 or 20 cm above the ground. In most cases, it sprouts quickly.
After winter dormancy
Once the winter months and the threat of frost are over, you can free the rosemary from its protective cover. It makes sense to remove the cover for only a few hours at first. This will allow the rosemary to slowly acclimate to the new environmental conditions and temperatures. If you have covered the soil in the pot with leaves or mulch, this protective layer can now be removed. This also applies to coconut mats or polystyrene sheets.
