Planting, caring for & harvesting cranberries

Cranberries are found throughout the northern hemisphere and have long been used as food. We introduce the different types of cranberries and give tips on cultivation and use.

The tart and sour fruits of the cranberry were already used by the Nordic aborigines as a food rich in vitamins. The cranberry, which is in demand as a source of vitamin C in winter, is also one of the cranberries. In this article you will find information about the origin and different types of cranberries, as well as about the successful cultivation and use of the cranberry fruit.

Cranberry: flower, properties and origin

The species group of the cranberries is closely related to the blueberries (Vaccinium myrtillus and Vaccinium corymbosum) and cranberries (Vaccinium vitis–idea) related. All three berry varieties belong to the same genus (Vaccinium) and the heather family (Ericaceae). As cold and frost-tolerant bog dwellers, cranberries are found in all subpolar to moderate climate zones of the northern hemisphere around the Arctic Circle. Cranberries are ground cover, they grow low and creeping. The leaves are oblong and lanceolate, they are barely larger than 1.5 centimeters and shiny dark green. The flowers of the cranberries are typical of heather plants: small and with rolled-back petals, white to pink or reddish. They bloom between May and July. Bees and bumblebees love to pollinate the flowers. Round berries later develop from this, which turn red to dark red, sometimes shiny, by the time the cranberries are harvested - between the end of August and October. The taste of cranberries is generally sour-tart. The fruits have a very long shelf life and are mainly enjoyed processed.

The different types of cranberries

Among the cranberries there are various species that have developed in their respective homeland. They differ in growth and fruit texture. We introduce you to the four types of cranberries.

common cranberry (Vaccinium oxycoccos)

The common cranberry or swampberry is widespread in boggy, acidic locations in Great Britain, Scandinavia and northern Russia. However, it can potentially also find a suitable habitat in moor areas in many European countries, including Germany. The far-creeping subshrub has leaves that are a maximum of 1 cm long, which shine dark green in summer and turn reddish in winter. From June to July, the common cranberry flowers on long hairy flower stalks and then forms pea-sized fruits that are dark red when ripe. These taste juicy and sour, have a high vitamin C content and are used like cranberries. Common cranberries are therefore not only suitable as an ornamental plant, but also as a very high-yield crop plant.

Large fruited cranberry (Vaccinium macrocarpon)

The large-fruited cranberry is also known as cranberry or American cranberry. It originally comes from the boggy and coastal areas of Northeast America and Canada, but also grows well in this country. Commercial cultivation has long been important in the states of Oregon and Washington. The ground-covering cranberry shrub grows 10 to 30 cm high and forms long, creeping, evergreen shoots. The white-pink flowers, rolled backwards, appear from June to July, the dark red, 1 to 2 cm large, round cranberry fruit ripens from the end of September. In harsh locations, cranberries are sensitive to frost and drought, so they need a somewhat sheltered location. Cranberries are great for growing because of their size and the many varieties available, and they are a bit less specific when it comes to their site requirements.

Small-fruited cranberry (Vaccinium microcarpum)

The small-fruited cranberry is widespread in large parts of northern Europe, also in Germany, also in North America and slightly in northern Asia. In contrast to the common cranberry, it forms smaller fruits and leaves, as well as shorter shoots. The dwarf shrub is only 5 cm high and develops 30 cm long, evergreen shoots. The tiny bell-shaped flowers bloom from May to July. The juicy, sour fruits of the small-fruited cranberry later grow on long, hairless stalks, and take on a dark red color when they ripen in late autumn. After exposure to frost, the berries acquire a sweeter taste. However, the small-fruited cranberry is more ornamental than a useful plant, because it grows slowly and only produces small berries.

southern cranberry (Vaccinium erythrocarpum)

The southern cranberry (Vaccinium erythrocarpum subsp. erythrocarpum) or "Southern Mountain Cranberry" is found in the mountainous southeastern United States. As an Asian subspecies (Vaccinium erythrocarpum subsp. japonicum) but is also native to Korea, China and Japan. The deciduous shrub reaches a height of 1.5 meters. The reddish flowers with rolled-back petals that appear in June are particularly striking. Translucent, partly dark red berries with a sour, tart taste develop from this in autumn. The southern cranberry can be harvested well, because a worthwhile amount of berries comes together on the comparatively large shrub.

Planting cranberries: location and procedure

As bog dwellers, the common cranberry and the small-fruited cranberry in particular are tied to rather special locations. All representatives of this genus need moist, acidic and sandy-humic, but not particularly nutrient-rich locations that never dry out completely. Calcareous, sandy, clayey or too dry soils are completely unsuitable for cranberries, they die there in a very short time. In these gardens, the moor dwellers can only be cultivated in pots and tubs. Cranberries and southern cranberries are slightly less demanding and can usually be planted in established bog beds. For this purpose, the top layer of earth is removed and replaced over a wide area at a height of 15 to 20 cm. The pH of the soil is lowered to 4 to 5 so that the moor dwellers feel comfortable. You can use the removed topsoil for balcony boxes, pots or raised beds. To create good site conditions for cranberries, mix rhododendron soil with approx. 10% sand and acidic materials such as bark humus, spruce needles or grape pomace. With this mixture you now replace the excavated topsoil, roll the whole thing or let it sink for two weeks.

Once the soil has been prepared, the cranberries can be planted. With young plants, place 7 to 9 pieces per square meter, which soon results in a dense meadow of cranberries. The plants are not placed lower than when they were in the pot. Water well after planting so that enough soil is washed to the roots and the cranberries can take root well. Then cover the surface of the soil between the plants with fine bark mulch. This protects the slow-growing cranberries from heavy weed growth and keeps the soil moist.

The most important care measures

Cranberries require little care. The effort is mainly limited to removing weeds in the bed. In dry summers, cranberries should be watered regularly.
The nutrient requirement of cranberries is very low, but fertilization may be necessary for mulched areas, since the degradation of bark mulch and co. by microorganisms binds nitrogen. If you are seeing slow growth and little new growth then using an organic liquid fertilizer like ours is the way to go Plantura organic flower & balcony fertilizer, recommended. However, only use the fertilizer in small doses, because cranberries can form untypical, long shoots or fewer flowers if the nutrient content is too high.
Cranberries do not need to be cut. Only diseased or senile shoots or excessively proliferating plantings should be pruned gently.

The leaves and flowers of cranberries can be damaged by late frosts in May; after budding, the temperatures must not fall below -2 °C. It is better to cover cranberry plants with fleece or jute at the time of the ice saints.

Grow cranberries

If you want to propagate your cranberries, you can do this by cutting the young shoots. To do this, cut off annual shoots about five centimeters long in summer and plant them almost entirely in a prepared soil mixture of acidic potting soil and sand. In the following weeks, the cuttings should always be kept well moist until they have formed roots and can be planted out.
Shoots lying on the ground can be used for sinkers: They also quickly form roots at the point of contact with the soil. These rooted shoots are cut off and transferred directly to a suitable location.

Are cranberries poisonous?

Cranberries are not poisonous and are hardly related to slightly poisonous relatives, such as the bog bilberry (Vaccinium uliginosum), to be confused. The latter forms dark blue, frosted berries on bushes up to 0.8 meters high, which lead to intoxicated states and dizziness after consumption of larger quantities. All cranberry species can be eaten raw, although they are often too acidic for that.

Cranberries: Harvest Time and Use

The harvest time for the various types of cranberries extends from the end of August to October. They are usually picked individually by hand. With the help of a harvest comb, such as that used in commercial cranberry cultivation, the small berries can be stripped off and collected much more easily and quickly. The berries remain in nature during the winter and can still be eaten in the following spring. The fruits of cranberries can be stored in a cool place for several months. This is due to the abundant, preservative ingredients, such as vitamin C, benzoic acid and vaccinin, but also to the protective layer of wax around the berries.

In addition to being eaten raw, the red fruits are processed into healthy cranberry juice, jam and compote. Similar to lingonberries, they are served with game dishes. By the way, cranberries do not need an additional gelling agent when they are boiled, their high pectin content allows them to thicken by themselves. In Finland and Russia, an alcoholic drink called kvass is produced from the common cranberry. Cakes and pastries can also be refined with the fresh, sour fruits. Dried cranberries keep for a long time and enrich mueslis, for example, with their high vitamin C content and refreshing acidity.

Not only cranberries can be found in our forests, they too blackberry (Rubus fruticosus) is native there. We reveal what is important when choosing the variety and planting the berries.