How to Grow Cranberries in a Pot
Cranberries are delicious berries that look beautiful too with their bright red color. The plants tend to grow in swamps and bogs, and if one doesn’t have a yard of their own, they may be disappointed with the thought that they can’t grow cranberries of their own. But the good news is that they can grow cranberries in containers!
Yes, this low-growing, trailing woody, evergreen perennial that grows along the ground forming a dense mat can grow even in containers.
Published: March 12, 2022.
What are Cranberries?
Cranberries (Vaccinium macrocarpon) belong to Ericaceae (Heath) family and are native to northeastern North America. These are vines and should not be confused with cranberry bush (Viburnum trilobum).
They occur in the US as well as Canada. It’s an evergreen, low-growing, dwarf plant growing around 8” to 10” tall and spreading around 2 to 5 feet.
Cranberry leaves are small and oval-shaped. The plant produces lovely bright pink flowers in the spring. They are pollinated by bees.
The long trailing runners running along the ground develop short vertical branches which are known as uprights. Berries grow on these uprights, although some berries grow even on the ends of the runners.
The berries ripen in the fall displaying dark red color and brown seeds inside.
Previously cranberries were grown only for ornamental purposes. However, since the time when their health benefits were found, they are produced commercially too.
Today cranberry production has reached an all-time high for their juice which is loaded with antioxidants, vitamins, and minerals. They are useful against liver disease and urinary tract infection, they lower blood pressure and improve eyesight.
American cranberry is the most popular variety and Washington, Oregon, New Jersey, Wisconsin, and Massachusetts are the highest producers of cranberry plants.
Cranberries are also grown in the provinces of British Columbia and Quebec in Canada. Actually, 98% of cranberry production comes from the US, Canada, and Chile. Some production also comes from Asia, Argentina, and central and northern Europe.
Eating raw cranberries is possible. However, they’re too acidic (tart) to eat fresh. Therefore, most of the cranberries are processed to make various products like juice, jam, sauce, muffins, cheesecakes, cookies, and dried cranberries.
Cranberries Growing Zones
Earlier it was believed that cranberries grew only in bogs and swampy areas. However, it’s clear now that they occur virtually everywhere in the wilderness, particularly in the USDA zones 2 through 7.
More than 100 varieties of cranberries grow in North America. Traditional varieties include Pilgrim, Red Star, Howes, Early Blacks, Searles, Stevens, McFarlain, and Ben Lear.
Other varieties include Mullica Queen, Crimson Queen, and Demoranville.
Out of these Ben Lear and Early Black are not recommended for beginners since they are more difficult to care for and more susceptible to diseases and insect infestation than other varieties.
When to Plant Cranberries?
One can plant cranberries at different times all through the year, depending on the age of the plant.
One can plant seedlings and cuttings throughout the fall, from October to early November, and even in the springtime from mid-April to May end.
The grower can plant a 3-year-old rooted plant sometimes in the summer, but they should be bought in pots.
How to Grow Cranberries in Containers?
Cranberries love acidic soil since they belong to the same family as that blueberries, rhododendrons, and azaleas which like acidic soil.
Their natural environment involves moist (but not waterlogged), sandy soil with organic matter and pH around 4.5 to 5.0. They prefer full sun to partial shade. They need protection from frost.
The grower has to have patience while growing cranberries because these berries fruit only after 3rd year. It’s common for growers to think that they’ve failed to create ideal soil conditions for the plant and give up.
To recreate the complex soil conditions preferred by cranberries, some growers form a shallow bed in their yard, line it with plastic having some drainage holes, and fill it with a potting mix designed for acid-loving plants to recreate a moist yet well-draining bog environment and water it often to keep the moisture levels high.
Choosing a Self-watering Container
Instead of applying the above-mentioned complicated method, there is a far easier method of using a large self-watering container, often known as ‘window boxes’ or ‘trough style planters’.
Such containers have a water reservoir at their bottom that can hold a few liters of water which keeps wicking upward keeping the soil moist.
This sub-irrigation system is actually an old method for growing plants indoors which has recently regained popularity. Cranberry roots are not deep but spread a lot hence need a wider pot.
This self-watering pot is then to be filled with a potting mix made for acid-loving plants, e.g. an azalea & camellia potting mix and an accurate amount of a slow-release acid-loving plant fertilizer (for example, slow-release azalea & camellia fertilizer granules) is to be applied in spring and fall.
Obviously one can even grow cranberries in aquaponic and hydroponic systems.
In short, cranberries don’t ask for much work. One can just keep the water reservoir of the self-watering planter topped up, feed the plants in early spring and fall and just relax and watch the plant growing.
Growers will be rewarded within around three years with their first crop of cranberries.
Also, many growers use wider raised bed planters, even with small transport wheels, for growing cranberries, strawberries, and even lettuce and other similar berries, vegetables, and fruits.
Preparing the Container
Gardening experts also advise using a large enough container with a good number of drainage holes, though they propose using self-watering containers as they would simulate a bog-like environment.
The gardener should fill the pot with acidic soil with a pH of 4.5 to 5.0. The soil should be rich in organic matter and peat moss.
In the wilderness, cranberry plants spread profusely by runners. Their upright canes will bear flowers and fruits once they complete 3 years of growth. However, the canes will die off a year after that and new canes will shoot up as they root.
Unfortunately, this can’t happen with potted cranberry plants. Therefore, the grower will have to replant their cranberry plants every few years.
Since the plants have a spreading habit, experts recommend using pots that are 12-15 inches (30.5-38 cm) or more in diameter. Since the plants have shallow roots that only go 6 inches (15 cm) deep in the soil, container depth is not as important as width.
The grower should test the soil pH every year in the spring. pH can be adjusted by adding a slow-release acidic fertilizer in the spring. This will also rectify any nutrient deficiencies.
Low-nitrogen fertilizers are good for cranberry plants and an annual application of bone meal will also benefit them.
Choosing the Right Location
The grower should place their cranberry plants in full sun for best fruit production.
Growing Cranberries from Cuttings
Growing cranberries from one-year-old cuttings or three-year-old seedlings are more popular than growing from seeds as growing from seeds is a much lengthier process.
The grower can buy rooted, one-year-old cuttings or unrooted ones that they can collect themselves. Rooting the unrooted cuttings needs patience, but for a dedicated gardener, the process can be fun.
The grower should take cuttings in very early spring or in early July from a plant that should be healthy and well-hydrated.
Time and Size of Cuttings
Using very sharp and sanitized shears, the grower should take cuttings that are 8 inches (20 cm) long. They should remove most of the leaves and any flower buds from the cutting, leaving only the top 3-4 leaves.
Using Root Hormone
The grower can dip the cut end of the cutting into a rooting hormone if desired.
Now they should insert the cut end of the cutting into a lightweight, nutrient-rich medium such as a mixture of compost and sand.
They should place the potted cutting in a warm shaded (indirect sunlight) spot in a propagator, frame, or greenhouse. The cutting should root within 8 weeks.
The grower should harden the newly rooted plant off and only then plant it in a larger container.
Growing Cranberries from Seeds
Growing cranberries from seeds need patience because they can take anywhere between 3 weeks and several months to sprout.
The grower should fill a 4-inch (10 cm) container or containers with a lime-free sterilized growing medium and firm it down and place the containers in a watering tray that is deep enough to hold 2 inches (5 cm) of water.
Then they should fill the tray with sufficient water to let the pots soak up enough to become moist. They should firm the soil again and remove any remaining water in the tray.
Now they should poke 2-3 holes in each container and place 2 cranberry seeds into each hole. They should cover them with a light layer of the growing medium.
They should place the container/s in a spot that remains at 65-70 degrees F (18-21 degrees C) for 4 weeks in bright but indirect sunlight. During this period, the growing medium should be kept consistently moist.
After 4 weeks, the grower should move the containers to a cooler spot with temperatures around 25-40 degrees F (-4 to 4 degrees C) for 6 more weeks. The period of cooling off will help jumpstart the germination process. The grower should make sure the pots are slightly damp.
After 6 weeks, the grower should transfer the containers to another spot where temperatures should be consistently 40–55 degrees F (4-13 degrees C). They should leave the containers to let the seeds germinate at this temperature while keeping them slightly moist. At this juncture, sprouting may take as short as 3 weeks to up to several months.
Growing from Seedlings
Cranberries can also be grown from seedlings which the grower can buy from a garden store or plant their own seedlings when they become old enough.
To grow seedlings in pots, they’ll need a 12- to 18-inch wide and 8-inch deep container. They should choose an ericaceous potting mix with a pH of around 4.5 to 5 and good drainage.
Since cranberry plant roots don’t grow deep, often only 4 to 6 inches, but their runners spread and need space for spreading, the grower should be extra vigilant about irrigation because pots dry out much faster than garden soil.
How to Take Care of Pot-grown Cranberries?
The grower should water their cranberry plants regularly so as to keep the soil consistently moist, though not soggy.
During the first few weeks of the growth of seedlings, they should water daily. Once seedlings are established, they should water every 2 days.
They should make sure all weeds around the cranberry plant are removed.
The gardener should prune the runners of the cranberry plants from the 3rd year of growth. From the third year onwards, they’ll have to prune the plants each spring to control the runners and promote uprights.
The grower can use a landscape rake to comb the runners so as to make them go in one direction so that they can identify the longest runners and cut them back. They should not prune the existing uprights.
The grower should fertilize their plants every 3 to 4 weeks with a slow-release fertilizer. After that, they should follow up with a balanced liquid fertilizer to promote growth.
The grower should apply a thick layer of mulch in the winter to protect the plants from snow, frost, and cold.
Pests and Diseases
Cranberries have quite a few pest enemies which can destroy them. Here they are.
Larvae feed on new growth, flowers, and fruit. Late-season flooding is good for control.
Larvae feed on fruit from inside out, forming an entrance hole covered with webbing. The grower can spray an insecticide or hand pick and dispose of the worms.
Maggots eat leaves, forming a cupping effect. The grower should apply an insecticide during the first hatch period of the growing season, which is usually in mid to late spring.
Larvae eat up roots, runners, and stems, turning leaves brown in late summer. Insecticides in late summer to early fall can be the best treatment.
Brown, green, and big cranberry snapworms are all active cranberry pests. Larvae eat leaves, flowers, hooks, and pods.
Fortunately, they can be controlled with most insecticides.
Cranberry Flea Beetle
Also known as the red-headed flea beetle, adults skeletonize leaves during peak summer. Like several other flea beetles, these too can be controlled with certain insecticides.
Larvae hollow out flower buds before opening. Some chemical control can be effective. However, Weevils continuously keep becoming resistant to it.
These worms join leaves and tips of the vines together with webbing and cause browning of uprights. The grower can use spring flooding and insecticide for control.
Aphids and Ants
Although a rare problem, aphids may occasionally feast on cranberry plants and their honeydew (their secretion) may attract ants. By removing aphids, the grower can take care of ant problems.
A variety of sap-sucking insects including scale and spider mites feed heavily on cranberries. Spider mites are hard to notice with the naked eye but can be identified from their small spider-like threads of silk.
Scale insects are difficult to notice too, but not because of their size, but due to their camouflage.
Both these pests can be eradicated using neem oil or insecticidal soap. The grower should follow the manufacturer’s instructions.
Caterpillars love cranberries a lot. Hence the grower should keep an eye on whether moths are laying eggs in the plants. Black-headed fireworms, cranberry tipworms, cranberry fruitworm, and others can cause devastation of the plants and fruit production, particularly if the grower doesn’t notice them until they establish well.
Most caterpillars can be dealt with using targeted insecticides.
However, the grower should be sure to use them in the evening, after bees return to their hives. However, it should be remembered that some targeted insecticides have a short life, and may be required to be reapplied as new waves of caterpillars hatch.
Anyway, whenever using chemicals of any sort in the garden, be sure to read the instructions and to adhere to them!
Certain diseases too are common in cranberries.
This disease is marked by a cottony fungus that thrives inside the berries and the stem tips withering into a shepherd’s crook shape. It can be prevented by improving drainage and infected fruits of the previous year.
The attractive name of the disease comes from the fact that it causes new growth to turn thick and pink, like a rose. It can often be prevented by increasing sun exposure and airflow. If already infested, the plants should be treated with a fungicide.
Red Shoot Disease
If early growth turns frail and becomes red, the plant has been attacked by red shoot disease. Although it may seem strange, this disease is not actually serious but doesn’t have a definitive treatment.
Leaf spots can be caused by a number of bacterial and fungal issues in cranberries.
These include early leaf spot, Cladosporium leaf spot, Pyrenobotrys leaf spot, Proventuria leaf spot, and red leaf spot.
These diseases flourish in moisture and can often be prevented by watering during the day when the water gets time to evaporate and making sure the soil drains well. If the infestation has already occurred, it should be treated with a fungicide.
False Blossom Disease
This disease is transmitted by the blunt-nosed leafhopper. It causes flowers to grow erect and never turn into fruit. The grower should use insecticides if they notice any leafhopper infestation.
There are several causes for bitter and blotch rot, hard rot, scald, and viscid rot. The grower can prevent it by ensuring the vines don’t sit in water for too long. If they use flooding, they should do it only late in the season.
This disease causes leaves to turn dark brown and then light tan and stay on the vine cross the winter. It can be prevented by allowing good sun exposure and air circulation, and by using a fungicide.
In this disease, shoots die back and growths form on stems. Bacteria enter through wounds.
Therefore, this disease can be prevented by preventing damage caused by humans and winter. The grower should use sprays containing copper if the infection isn’t bad.
One can typically harvest cranberries in the fall. If the grower plants a three-year-old seedling, their plant may produce berries by the following fall.
But if they’ve planted a one-year-old cutting, they may need to wait for 3 to 4 years before the plant bears fruit.
Growers can easily identify that they are ready for harvest because they’ll turn from green to red which typically happens from September to late November, depending upon when the planting was originally done.
Once the plant starts producing berries, growers can harvest them from September to November every year. It’s important to harvest all the berries before the arrival of the first hard winter frost as they cannot tolerate temperatures below 30-degree F (-1 degree C).
After harvesting, cranberries will stay fresh for up to two months if stored in an airtight container in the refrigerator. This is a longer period of staying fresh than that of most fruits.
If cooked or made into a sauce, cranberries will stay intact in the fridge for up to a month, whereas dried cranberries (which have a texture similar to raisins) will last up to a year.
Thus, if any gardening enthusiasts were sad with the thought that they can’t grow their own cranberries, they now have a reason to cheer up. They can grow their very own cranberries and surely, they’ll enjoy the process a lot!