Strawberries are perennial plants that with a little pruning and preparation can be successfully overwintered. Find out what to do with strawberry plants in winter here.
Strawberries (Fragaria) in the hobby garden ideally stay in the same bed for about three years. For the plants to produce good yields during these three years, they must survive the winter undamaged each year. Because the strawberry flowers already begin to form in autumn, overwintering has a significant impact on the next year’s yield.
Pruning strawberries in preparation for winter
Freshly planted strawberries are not pruned in autumn. For plants that have already borne fruit, prune back the foliage. This important step before overwintering serves as precautionary measure: by removing leaves infected with fungal diseases such as strawberry powdery mildew (Podosphaera Pannosa) or grey mould (Botrytis cinerea), it prevents the spread of diseases. Prune back the strawberry plant right after harvesting and no later than mid/late July. Do not prune late-bearing strawberry varieties. As the remaining growing season after harvest is too short for new leaves and flowers to form, pruning after mid-July would have a negative effect on flower formation and yield the following year.
When cutting back the strawberry leaves, it is essential to ensure that the crown remains undamaged. If this can be guaranteed, you can also cut them back with your lawn mower – set as high as possible – or a strimmer. However, manual pruning is still recommended, as this does not leave such large wounds through which diseases can occur, and any infected leaves will not be dispersed over the bed. Collect all the leaves and remove from the strawberry bed. They cannot be used as mulch due to fungi being able to survive on dead leaves and then pruning would be pointless. If you have a well-functioning compost heap that heats up a lot, you can add the leaves to it if they are not already visibly diseased. In addition to the leaves, remove all superfluous shoots and runners. After pruning, fertilise the strawberries straight away. A predominantly organic slow-release fertilizer, such as our Plantura Tomato Food, is ideal for this purpose. It is applied around the plants, worked into the surface and lightly watered. Thanks to its even, slow release, the plants are supplied with essential nutrients for weeks. The increased potassium content also promotes winter hardiness.
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Tip: Remove diseased and wilted leaves from the crop as soon as possible, this also applies to everbearing varieties.
Summary for cutting back strawberry plants:
- Cut the leaves off the strawberry plants after harvesting or by the middle/end of July at the latest
- Leave the leaves of very late-bearing varieties on the plant
- Take care to not damage the strawberry plant’s crown during pruning
- Do not use the leaves as mulch, rather remove and compost
- Feed strawberry plants directly after pruning
What to do with strawberry plants in winter
Strawberry plants are still very small and vulnerable the first year they are planted. Plant the strawberries by mid-August at the latest to give them a chance to grow well and survive the winter successfully. Both the roots and the flowers of the strawberry plants must be protected from frost. Because the roots are not particularly deep, they are not well insulated. When overwintering strawberry plants, it is essential to protect them from late frosts, as the flowers are sensitive, especially in spring.
Are strawberries hardy? Strawberries are perennial and hardy down to about -10 °C , but they still like a little extra protection from the cold in winter. The method varies depending on whether you are overwintering strawberries in a bed or a pot.
Overwintering strawberries in pots
Strawberries in pots or window boxes have the advantage that they are mobile. Place in a sheltered spot over the winter, ideally near a house wall and on an insulating material such as wood or polystyrene. If you live in a frost-prone area or want to be on the safe side, cover your plants with brushwood, straw or fleece when overwintering strawberries in pots and wrap the planters with jute, garden fleece or cardboard. If you have strawberry plants under a protective roof, do not forget to water them a little on frost-free days. But be careful: do not water too much, lest the water in the soil freeze during the next frost and damage the roots.
Tip: Many strawberry varieties are sensitive to late frosts – do not uncover them too early.
Overwintering strawberries in a garden bed
Strawberries in beds are exposed to their surroundings as they are not protected. As a result, they are already happy when planted in beds that are not overly exposed to the wind nor overly wet. Pay attention when choosing a spot and preparing the soil because waterlogging can cause significant frost damage to the roots of the strawberry plants in winter. If your garden is prone to waterlogging due to clayey soil, add sand to the soil to provide better drainage.
Planting strawberries in a mound bed or in raised beds about 40 cm high is another way to overwinter strawberries in poor soil by avoiding water-related damage. Depending on the region, cover the strawberry plants in the same manner as those in pots. Cover the strawberries with leaves, brushwood, or garden fleece. Do not use plastic sheeting, as this is not air-permeable and can lead to disease. In spring, do not remove the frost protection too early. Late cold snaps and late frosts can otherwise greatly damage the flowers. A black pistil is the typical symptom of flowers that have been frostbitten. Unfortunately, they will no longer bear fruit.
Protect strawberries successfully from frost:
- Place pots and planters in wind-protected locations
- For pots in covered areas, do not forget to water moderately on frost-free days
- Cover strawberry plants in pots or beds in cool regions with fleece, leaves or brushwood
- Keep the plants covered until the last late frost because strawberry flowers are sensitive to frosts in spring