Growing Blueberries in Pots and Containers
Blueberries can be easily grown in containers and flower pots; just be aware of blueberries' specific needs regarding soil, nutrients, moisture, sun exposure, etc.
When grown properly, even small varieties can yield impressive amounts of these healthy fruits per individual plant.
Updated: November 4, 2023.
How Big Do Blueberry Bushes Get
Blueberry bushes, when grown in their ideal natural environment, can reach varying sizes depending on the variety.
For instance, the highbush blueberry, a common type in North America, can grow to a mature height of 6 to 12 feet with a spread of up to 8 feet.
On the other hand, the lowbush variety, often found in colder climates, generally reaches a modest height of 1 to 2 feet.
The rabbiteye blueberry, thriving in the Southern United States, can grow up to 10 feet tall.
These sizes reflect the bushes' potential when planted in open ground with optimal conditions for root expansion and canopy development.
However, the dynamics change considerably when growing blueberries in containers. The constrained space limits root growth, which in turn impacts the overall size of the plant.
When cultivating blueberries in containers, dwarf and half-high varieties are often preferred. These cultivars are specifically bred to thrive in limited soil volumes and will typically grow to be about 1 to 2 feet tall, and sometimes up to 3 feet if the container is sufficiently large and the plant is well-cared-for.
Container-grown blueberry plants also tend to have a more compact and bushier form. This controlled growth does not just serve aesthetic purposes; it's also a practical adaptation.
A smaller, more contained root system in a pot restricts the plant's access to nutrients and water when compared to in-ground plants, thereby naturally dwarfing the bush.
It's crucial for gardeners to select containers that will accommodate the full size of the bush, keeping in mind that while the container limits the size, adequate space is still needed for the blueberry bush to flourish and produce a satisfactory yield.
Regular pruning and the correct pot size can help maintain a healthy size and shape for the blueberry bush, ensuring it remains manageable and productive within the confines of container growing.
Containers and Pots For Blueberries
Although blueberries have a relatively shallow root system, one has to use larger containers and pots. Pots with a diameter of at least 50cm (20 inches) are recommended, and if one is using long, rectangular containers, they should be at least 35-40cm wide (14-16 inches) with plants being spaced apart at least 40-50cm (16-20 inches).
Of course, these sizes and distances depend on plant sizes, and for container cultivation, low-bush types of blueberries are preferred types (for example, Sunshine Blue, Patriot, and Top Hat varieties). If one has room for larger containers, feel free to choose blueberry varieties that can grow up to or even more than 1.8m (6 feet).
However, for small gardens and similar locations, small(er) varieties are recommended.
Containers and pots for growing blueberries should have enough drainage holes since blueberries prefer moist but not soggy soil. In heavy, soggy soils, root rot can develop and kill the plants.
Blueberry Soil Mix - How To Make Acidic Soil
One of the specifics when growing blueberries is their acid soil requirement. They will grow in soils with a pH between 3.5 and 6.5, but they prefer soils with a pH between 4 and 5.
And this can sometimes be really hard to achieve in home gardens for longer periods. But, when growing plants in containers, one can choose and prepare soil for that type of plant specifically - in this case, blueberries.
There are several ways one can prepare proper soil for blueberries. One of the simplest ways is to mix two-thirds of ordinary potting mix and one-third of the potting mix designed for plants like azaleas, rhododendrons, camellias, hydrangeas, etc., or one-third of peat moss.
Also, adding pine bark, humus, and similar organic matter can help keep pH levels in the optimal 4.5 - 5 range.
One similar blueberry soil mix recipe:
- three-fifths of ordinary potting soil,
- one-fifth perlite,
- one-fifth of pine bark, shredded, at most 6mm (0.25 inch) in size.
Perlite is great for keeping the soil well aerated, and the pine bark adds organic nutrients and keeps the soil acidic.
Blueberries will suffer mineral deficiencies in higher pH soils - especially will suffer from iron deficiency as their ability to absorb iron decreases with higher pH. Iron-deficient blueberries have yellow leaves, grow slowly, are prone to diseases, and have very low crop yield, if any.
Blueberry soil mix should keep moisture well but also be well aerated, and any excess water should be able to drain away easily. Also, adding humus and pine bark mulch enriches the soil and keeps the acidic level in check.
Preparing the Pots and Containers for Blueberries
When preparing pots and containers for blueberries, be sure that the soil has good drainage and low pH.
Personally, the best time to prepare the pots and soil for blueberries is in autumn - during 5-6 months, the soil will settle down, and bacteria in the soil will do their task of breaking down the organic and inorganic matter and decreasing the pH.
In a suitable pot, make at least 3-4 large enough holes for good drainage. In the photo, four holes are made, and four more to go. Pots are ~24 inches (~60 cm) in diameter.
Fill one-third or one-half of the pot with potting mix and add:
- half an ounce of NPK fertilizer for blueberries,
- one tablespoon of organic fertilizer,
- half a tablespoon of sulfur.
Mix everything thoroughly and fill the rest of the pot with potting mix until the pot is almost filled.
- half an ounce of NPK fertilizer for blueberries,
- one tablespoon of organic fertilizer,
- half a tablespoon of sulfur.
Mix everything and fill the rest of the pot with soil. Add some water and cover the pot with plastic wrap so that rain can't wash away the nutrients from the pot.
Bacteria in the soil require months to convert sulfur and decrease the pH - nonetheless, in spring, before planting the blueberries, be sure to check the pH from the center of the pot.
Note: while fertilizers are added in small amounts 2-3x per year, sulfur is added every 1-3 years in small amounts, usually one tablespoon per pot, depending on the pot size and soil pH. Personally, add one good teaspoon of sulfur per 24-inch pot per year and mix it well with the rest of the soil, but very carefully.
Fertilizing Blueberries in Containers
Blueberries don't require plenty of nutrients; however, when fertilizing them, one has to try to keep pH levels around 4.5 - 5.
Use of organic fertilizers is highly recommended: compost, humus, worm casting, and similar. Also, when using artificial fertilizers, choose fertilizers for acid-loving plants - such plants prefer nitrogen in ammonia form (NH4), while typical fertilizers have nitrogen mostly in a nitrate form (NO3).
It is recommended to add fertilizers twice a year.
However, it is perhaps better (at least, I like it that way) to add smaller amounts of fertilizers more often, even on a monthly basis. This will keep nutrient levels more or less constant, and adding acidic fertilizers will keep the pH level where it should be.
If possible, use more expensive NPK fertilizer optimized for berries with gradual (slow) release of nutrients – such fertilizers feed the plants for up to 4 months and help with keeping pH around 4.5 - 5.
Watering Blueberries in Containers
Blueberries require between 3 and 5 cm (1-2 inches) of water per week. Of course, during the summer heat, water them more often - almost on a daily basis. Also, positioning the plants to be in half shade during summer heat can help; just be sure to move plants back to full sun positions after the summer is gone.
The hard water reduces the acidic level of the soil and makes it more alkaline (pH rises), inhibiting the uptake of iron and other nutrients by the blueberries - it is good practice to check the pH levels of the soil mix in containers regularly if possible on a monthly basis.
Pollination and Other Issues
Although some varieties of blueberries are self-pollinating, it is always better to have at least 3 blueberry plants for pollination and keep them close to each other. Also, having different varieties can extend the blueberry season significantly.
To protect blueberries from birds, cover the plants with a light net a few weeks before the fruits are ripe.
Root protection in containers - when growing on a garden soil patch, roots are protected by a soil layer from sun heat and winter cold, but when growing in containers, roots come in contact with the inner side of containers.
During winter, cold can damage roots in the containers - if possible, put containers away from cold winds and prevent them from freezing.
When choosing containers and pots, be sure to stay away from dark colors - such colored containers can reach rather high temperatures during summer and can damage the plants inside, plants that come in direct contact with them, and can even cause burns on humans and pets!
Growing blueberries in containers, long story short:
- choose pots and containers according to the size and number of your plants, and plant preferably only one plant per pot,
- choose varieties according to your location,
- the soil must be acidic, should keep moist well, but also should be well aerated,
- use organic fertilizers and fertilizers with gradual release of nutrients,
- water regularly, just be sure that any excess water can drain away,
- birds like blueberries, so be sure to protect the blueberries from them.
For more on growing blueberries, feel free to check How to Grow Blueberries article.
Frequently Asked Questions (FAQ)
Here are some of the most common Frequently Asked Questions (FAQ) about growing blueberries in containers:
Can blueberries grow in pots?
Yes, blueberries can indeed be successfully grown in pots.
Container cultivation of blueberries allows for greater control over soil conditions, which is beneficial given blueberries' preference for acidic soil.
Moreover, pot-growing can mitigate the risks of soil-borne diseases and allows for mobility in optimizing sunlight exposure.
To ensure healthy growth and fruiting, it is essential to choose the right variety—typically dwarf or half-high cultivars—and a container of adequate size with proper drainage, as well as to monitor watering and feeding more closely than with in-ground planting.
Do you need two blueberry bushes to produce fruit?
Blueberry bushes are known to benefit from cross-pollination, which involves the transfer of pollen from the flowers of one blueberry bush to those of another.
This process can enhance the fruit set and size of the berries. While some blueberry varieties are self-pollinating, meaning a single bush can produce fruit on its own, the presence of a second bush of a different variety can significantly increase yield.
For instance, highbush blueberries, one of the most common types, are partially self-fertile but will produce better if cross-pollinated with another variety that flowers at the same time.
In contrast, rabbiteye blueberries require cross-pollination from another rabbiteye variety for effective fruiting.
Therefore, while it is not strictly necessary to have two blueberry bushes to produce fruit, it is generally recommended for optimal yield and berry quality.
For gardeners with limited space, especially those growing blueberries in containers, ensuring the chosen variety is self-pollinating or using a self-pollinating variety alongside another compatible type can be key to successful blueberry cultivation.
Will blueberries survive winter in pots?
Blueberries can survive winter in pots, but they require some special care due to the less insulated container environment compared to in-ground planting.
The roots of blueberry bushes are less protected from cold temperatures in pots, which can lead to freezing and damage if proper precautions are not taken.
To improve the chances of blueberries surviving the winter in pots, here are some measures that can be taken:
- Insulation: Wrap the pot with insulating materials such as burlap or bubble wrap to provide a buffer against cold temperatures. You can also place the pot against a south-facing wall to take advantage of any warmth from the building.
- Location: Move the pots to a sheltered location, like an unheated garage or shed, where they will be protected from wind and severe temperatures but still experience the necessary dormancy period.
- Mulching: Apply a thick layer of mulch over the soil surface to help insulate the roots. Organic materials such as straw, pine needles, or wood chips are suitable mulching options.
- Watering: Ensure the soil in the pot does not dry out completely, as this can increase the risk of frost damage. However, avoid overwatering as this can lead to root rot, especially in cold conditions.
- Pot Material: Use pots made of wood, thick plastic, or ceramic with a frost-resistant glaze to provide additional insulation. Avoid thin plastic or metal containers that can change temperature rapidly.
- Size of Pot: Larger pots hold more soil and, therefore, provide more insulation. Ensure your blueberries are in appropriately sized containers to buffer the root system.
These steps can help ensure that your blueberry bushes remain healthy over the winter and are ready to grow and produce fruit in the following season.
It is also important to choose blueberry varieties that are suitable for your climate and hardiness zone, as some are more cold-tolerant than others.