If you want to harvest clean fruit, bed your strawberries on straw. Mulching helps to avoid gray mold, but it also has disadvantages.
Strawberries are originally residents of the edge of the forest. Therefore, by nature, they love soil cover, as created by the mulch layer of straw. But mulching strawberry plants has other, quite practical reasons.
Why do straw under strawberries?
A mulch layer of straw not only looks neat and helps to simulate the natural site, it has the main purpose of keeping the fruit clean and protect them from fungal diseases. If strawberries lie directly on the ground, rain and irrigation water splashes up the soil. The seeds sit on the outside of the fruit. Churned dirt easily settles in the indentations. Since the delicate fruits cannot be scrubbed like root vegetables, it is better to ensure the cleanest possible conditions as a preventive measure. If you have to wash the fruit for too long, the valuable vitamin C is also lost.
Too much moisture, however, is already harming the fruiting habit. The feared gray mold strikes more quickly on strawberries that are lying on the ground. It covers the fruit with a white-gray down until it rots. A straw base will help here, too. The strawberries are airy and can dry quickly.
The strawberry plants themselves prefer a moist soil. A layer of straw allows water to penetrate the soil, but it does not evaporate as quickly. Strawberries benefit from even moisture in two ways: they grow better and are healthier. This makes them less susceptible to fungal diseases. The positive side effect of a straw layer, that the fruits are spared from slugs because they don’t like to crawl over the bulky material, is unfortunately deceptive. In damp weather, they hide under any mulch layer.
How to mulch strawberries correctly?
The best time to put straw under the strawberries begins with flowering, depending on the variety, from late April to early June, and depends on the weather conditions. One tip is to wait until most of the petals have fallen off and the first still-green fruits are showing. The idea behind this: Allow the soil to warm up for as long as possible. This is because warm soil accelerates fruit ripening. Straw, on the other hand, insulates. In cold regions, it is therefore better to apply it later. In mild regions, but also due to climate change, the soil warms up faster. Then it may even make sense not to wait too long before applying the mulch. The insulating layer prevents the soil from drying out too quickly. However, if a rainy period is imminent, it is better to wait. Straw soaks up during prolonged rain and then no longer fulfills its actual purpose. In summary, in sunny, dry weather, spread the loosened straw around the plants at the beginning of flowering, in cool, damp weather it is better to do it a little later.
Before mulching, the soil should again be thoroughly cleared of weeds. Subsequently, the mulch layer of straw, by the way, saves further weeding. The layer should be appropriately thick, but not too thick. The rule of thumb for mulch layers is three to five cm (1.2 to 2 in). Keep in mind that as straw rots, it removes nitrogen from the soil, which perennial strawberry plants need for a good yield. Therefore, it is advisable to apply fertilizer before mulching. Because straw behaves similarly to bark mulch or sawdust, fast-flowing, mineral fertilizers have proven most effective. In home gardens, however, people often prefer organic fertilizers such as horn shavings and organic berry fertilizers or even vegan fertilizers.
Straw is provided by a variety of grains. Not all are equally suitable. The best experience has been with rye straw. It rots slowly and absorbs the least moisture. Some users, however, find straw as it is known as bedding in the horse or cow barn too coarse. If you have the option, chop the material before laying it out. Chopped and dehusked straw can be found in stores as small animal bedding. Do not use straw treated with so-called stalk shorteners between your strawberries, as is sometimes done in agriculture to increase the stability of the stalks.
After the last harvest, you can remove the straw by pruning back the strawberry plant leaves. Sometimes you hear the advice to leave the straw between the rows and work it in in the fall. In this case, special care should be taken to ensure that the soil is sufficiently fertilized. In addition, some people are bothered by the stalks flying around. For these reasons, many strawberry gardeners are looking for alternatives.
What other mulch material can you use besides straw?
Sometimes you can see wood wool as a base. The material dries faster than sawdust, which is also used. Since shavings of Miscanthus, a Chinese reed grass, have come on the market, experiments with the mulch material are underway. Between strawberries, however, it turns out to be very picky and makes harvesting difficult. It also removes nitrogen from the soil. Bark mulch is not recommended because of the nitrogen issue and an increased risk of fungal infection with poor quality bark mulch. A better mulch material is dried lawn clippings. You can also try hay. However, the grass seed it contains will scatter and increase the emergence of unwanted weeds in the strawberry bed.
Biodegradable mulch covers offer a real alternative. The cheapest alternatives are grain-based mulch films like those used for salad crops or garden mulch paper made from renewable resources. In the higher price range, you can find cover rolls made of hemp and jute or weed protection mats made of sheep’s wool, which provide a soft bed for strawberry fruits and keep them clean.
An insider tip are fern leaves. Simply place whole fronds between the rows. After harvesting, they disintegrate, so you only have to rake off the fronds.