By: Darcy Larum, Landscape Designer
Once purely decorative, container gardens are now pulling double duty, designed to be both aesthetic and functional. Dwarf fruit trees, vegetables, herbs, and berry producing plants like cranberries are now being added to multi-functional container designs. You may be thinking: hold on a minute, potted cranberry plants? Don’t cranberries grow in large bogs? Can you grow cranberries in a pot? Let’s learn more about growing cranberries in containers.
Not every gardener has the luxury of a huge yard to fill with plants. With so many amazing plants on the market these days, even those who do have large gardens may eventually run out of space. Lack of gardening space oftentimes leads to gardeners to try their hand at container gardening. In days of old, container plantings were generally the standard design which included a spike for height, a filler such as geranium and a trailing plant like ivy or sweet potato vine. While this classic, reliable “thriller, filler, and spiller” container design is still very popular, gardeners these days are trying out all sorts of different plants in containers.
Cranberries are low growing, evergreen plants that are native to North America. They grow wild throughout parts of Canada and the United States. They are an important commercial crop in many states. In the wild, they grow in swampy, boggy areas and cannot tolerate hot, dry climates. Hardy in zones 2-7, cranberry plants grow best in acidic soil with a pH of 4.5-5.0. If the right conditions are provided, cranberries can be grown in the home garden or containers.
A beautiful yet functional plant, cranberries spread prolifically by runners. Their flowers and fruits grow on upright canes once the plants are 3 years old. In the wild or in garden beds, canes die back after a year or two of producing berries, but new canes continually shoot up from runners as they take root. Potted cranberry plants do not usually have the room to produce these runners and new canes, so cranberries in pots will need to be replanted every few years.
Because of their spreading habit, it is recommended to plant cranberries in pots that are 12-15 inches (30.5-38 cm.) or more in diameter. Cranberries have shallow roots that only extend about 6 inches (15 cm.) into the soil, so container depth is not as important as the width.
Cranberries also grow well in trough style planters or window boxes. Being bog plants, container grown cranberry plants need soil that is consistently moist. Self-watering containers have a water reservoir from which water is constantly wicked up in to the soil, these containers work extremely well for potted cranberry plants.
Cranberries in pots grow best in rich, organic material or peat moss. They can also be planted in potting mixes for acid-loving plants. Soil pH should be tested at least once a year in spring. A slow release acidic fertilizer can be applied in spring to adjust the pH and correct any nutrient deficiencies. However, low nitrogen fertilizers are better for cranberry plants. They will also benefit from an annual addition of bone meal.
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Read more about Cranberries
Cranberries are small, trailing shrubs about 25 cm (10 inches) high. Plants produce runners from 0.3 to 1.8m long (1 to 6 feet). The vines form a thick mat over the surface of a cultivated bed. The stems are relatively thin, while leaves are green to dark green and rather small - they turn red-brown during the dormant season.
Flowers are white to light pink, around 8 mm long with a bell-shaped crown. The fruits consist of coral red berries that are sour, tart and aromatic in flavor.
Cranberries ripen from mid-August to late September. Red cranberry fruits contain organic acids, tannins, iron and other vitamins and minerals.
Cranberries reproduce by underground shoots that develop underground and develop trailing branches above the ground.
Also, it creates 'runners' – shoots that 'touches' topsoil develop roots and after some time these 'clones' can be replanted elsewhere.
Container for blackcurrants should be at least be 2 – 2.5 feet (60 - 75cm) wide and 20 - 24 inches (50 – 60 cm) deep. Smaller containers can be used too, just one would have to water more often and would have to limit the size of the plants. Also, smaller containers are easily moved around the garden, while larger containers must be positioned on the wheeled platform/stand.
Container’s bottom should have a number of drainage holes as good drainage is important. Place a 1 inch (2.5 cm) thick layer of gravel or stones over the bottom and fill the container with the soil rich in organic matter like well-rotted manure, compost and similar. Also adding well balanced NPK fertilizer with gradual release of nutrients can help the plants. Just be sure not to over-feed the plants.
However, a regular generous feeding and constant moisture, especially during the warmer months, is essential to ensure a healthy growth of the young plants.
Ben Sarek is supposed to be the best variety for growing in a container. This is because it is compact, ideal to be grown in the container. Moreover, it needs less pruning.
Varieties to Choose for Bigger Fruits
If you are passionate about bigger fruits, you can choose Big Ben, Ben Conan and Goliath, or even Laxtons Giant. The first two will give you real satisfactory results in terms of big fruits, almost twice the size of the standard fruit. They are easy to produce, reliable and frost resistant too.
Fertile soil helps further grow bigger fruits. Also the individual trusses should be thinned and also overall truss quantity should be reduced. On individual level, the trusses should not be let bear more than 3 to 4 fruits each. In this way, you can further maximize the size of individual fruits.
Watering is also an important component in producing exhibition standard fruits. Abundant amount of water at correct times given consistently is essential inconsistency in watering may give rise to split skins of fruits. On the other hand currants don’t like ‘wet feet’.
You will have to prune each plant. 3 tall canes should be set with equal distance between them in the pot. The fact is that blackcurrant fruit develops flowers best on the second year’s wood and not much on older wood. Therefore you should aim at encouraging some new canes each year which will produce fruits in their next season. After the first year of planting, many (7-8) new strong shoots should be grown by the summer end. You should not prune them in the first winter leave them to produce fruit in the following summer. Just remove weak growths if there are any, by cutting them to 1 inch (2.5 cm) above the soil.
When you grow blackcurrants in pots, you should keep them in good large containers for four to five years to grow and produce well. After this, you should repot the plant (you need not change the pot if you change it, let the new pot be slightly larger). Ideal time for that is winter.
While repotting, you can remove some of the old soil stuck to the roots. Then cut all the growth back to the base and let the plant restart and rejuvenate in the same pot with fresh new manure. After this the plant can continue in the same pot for the next four to five years.
Grow cranberries in a container that is at least 12 to 18 inches deep and wide or wider. Here are two methods: