When I began gardening in 2013, growing blueberries topped my list of garden priorities. Even though blueberries are one of the healthiest fruits you can eat, nothing beats the taste of the ones you grow yourself.
And if you’re trying to save money, growing your own blueberries will save you a lot of money over time compared to buying them at the store. Depending on how well you do, you might harvest more than you can eat. You can sell the extras to make some extra cash!
As a blueberry lover, few things disappoint more than harvesting your bushes and finding berries the size of peas. You wait all season expecting plump, juicy berries just to end up with these little nutritional teases.
So what causes small blueberries and what can you do to get bigger yields? Below I cover the major factors that stunt blueberry growth and provide tips to cultivate those large, mouthwatering berries you desire.
Pollination Problems
One of the most common reasons for blueberry runts is inadequate pollination during flowering Blueberries contain numerous ovules that get fertilized to form seeds. The more seeds that develop, the larger the berry size
Pollination issues stem from not having enough pollinator visits to the flowers. Bees play a vital role here – a single bee visit may only pollinate 1-2 flowers. It takes many trips for thorough pollination.
Poor weather is a big inhibitor of bee activity. Cold, wet, windy conditions during flowering keep bees in the hive. And since blueberry bloom time is early spring, unfavorable weather is common.
You can’t control the weather, but providing good bee habitat around your bushes is key. Having undisturbed areas, nesting sites, and supplemental floral resources will build your pollinator numbers and ensure more flower visits when weather permits.
Improper Soil Acidity
Blueberries need acidic soil with a pH between 4.2-4.8. Outside this range, the plants cannot properly take up nutrients which leads to reduced growth and yields.
Test your soil pH annually – it naturally rises over time To lower pH, apply elemental sulfur several weeks before planting and again if needed Mulch yearly with pine bark to acidify as it decomposes. Fertilize with formulations made for acid-loving plants.
Lack of Sunlight
Blueberries thrive best with full sun – at least 6 hours of direct sun daily. With less light exposure, the bushes put energy into foliage growth rather than fruit production.
Study sunlight patterns in your yard before planting. If your site gets under 6 hours of sun, look into removing obstructions like trees or buildings to increase direct light.
You can also try reflective materials like white-painted fences or galvanized steel that will redirect sunlight onto the bushes.
Improper Pruning
Pruning is vital for healthy, productive bushes. But improper pruning can stress plants, resulting in fewer and smaller berries.
Blueberries fruit on woody stems 2-6 years old. Avoid removing too many of these older canes when pruning – leave 4-6 canes per plant. Lightly trim young canes to encourage growth.
Never prune more than 20% of total bush volume in a single season. Take out old, dead, diseased and intertwined stems. Make cuts just above leaf nodes.
Age of Bushes
Don’t expect large yields from young bushes! Blueberry plants typically don’t reach full fruiting potential until their 3rd-5th year.
Be patient with new plantings, providing proper care over time. Growth and yields will slowly improve as the extensive root systems mature.
Meanwhile, older bushes eventually become less productive. Most commercial types decline after 8-10 years. Rejuvenate overmature plants by hard pruning to stimulate new cane development.
Genetics
Some blueberry varieties are naturally small-berried – an important trait for commercial growers who sell by volume. But for backyard berry lovers, seek out varieties marketed for large fruit size.
If your bushes are unlabeled, research the size ranges for common cultivated types. ‘Duke’ and ‘Bluejay’ produce extra-large berries. ‘Jersey’ is a classic mid-size berry. Small-fruit varieties include ‘Earlyblue’ and ‘Sunrise’.
When buying new bushes, check tags for expected fruit sizes. Seek descriptive terms like “Extra Large”, “Jumbo”, “Giant” to get those satisfying big berries.
Nutrient Deficiencies
Insufficient fertilization deprives bushes of nutrients needed to support fruit growth. This causes small, sparse yields with poor flavor.
Have a soil analysis done to determine specific nutrient shortages. Correct deficiencies by applying organic or synthetic fertilizers tailored to blueberries’ needs.
Provide 1-2 ounces of nitrogen per bush yearly. Acidic soils are prone to iron chlorosis – treat yellowing leaves with iron chelate supplements.
Water Stress
Blueberries require constant moisture, especially when fruit is developing. Inconsistent watering causes stress, slowing growth and reducing berry size.
Provide 1-2 inches of water per week from spring bloom through harvest. Extra water is needed during hot, dry weather.
Use drip irrigation or soaker hoses to maintain optimal soil moisture. Mulch helps retain soil moisture while preventing water loss.
Berry Plumpers
If your blueberry bushes are otherwise healthy, you can use natural plumping solutions as fruit ripens to increase size.
Applying seaweed extract mid-season provides micronutrients that boost fruit expansion. Spray plants every 2-3 weeks from green fruit stage until harvest.
Another option is a fruit plumping spray called Vintage Yield. Apply weekly starting 8 weeks after flowering to enlarge berry dimensions.
Enjoy the Treats No Matter the Size!
While tiny blueberries may not look too impressive, their sweet flavor and burst of antioxidants still makes them a nutritional powerhouse.
Try incorporating pint-sized berries into muffins, smoothies, or jams rather than eating them fresh. You’ll still reap the benefits without being disappointed in their size.
With knowledge of the various factors affecting blueberry growth, you can troubleshoot problems and pamper your bushes to reach their full potential. But even if you end up with mini berries, enjoy their tangy goodness that no size can diminish!
Other Requirements for Soil
If the pH of the soil is in line, blueberry bushes generally don’t require much. Even though they don’t need very fertile soil, soil that is full of organic matter will help them grow the most. If the pH is already in the right range for blueberries, you don’t need to fertilize them the first year. Just make sure there is a lot of organic matter around the plants.
After the first year, just as the bushes start to break dormancy, you can add an organic slow-release nitrogen source like cottonseed meal, soybean meal, or composted chicken manure. Personally, I only have to do this every couple of years. Blueberries really aren’t that picky with soil beyond the pH.
Mistake #1: Only planting one blueberry bush
Some blueberry cultivars are partially self-pollinating, but some are not. If they’re not, like rabbiteye blueberries that are grown a lot in the southern US, this means that at least two different kinds are needed to fully pollinate each other. If only one of these bushes is grown, flowers will form but berries will not.
But if you plant more than one bush of a different cultivar, even if they are partly self-pollinating (mostly northern highbush and southern highbush), you will get more berries each year.
Blueberry flowers are pollinated by bumblebees and other bees.
So, regardless of which cultivar you grow, for the best fruit production, you want at least two bushes.
However, I’d suggest planting even more if possible. The more diversity you can include, the better. It’s not just because they set a lot of fruit, though that’s a good reason. Also, different cultivars flower and fruit at different times. This can be advantageous for several reasons.
The most obvious is the longer period of harvest. If you have blueberry bushes that bear fruit early, mid-season, and late-season, you can pick them all month long.
When I planted my main blueberry planting, I chose to purchase five different cultivars. Though I didn’t plan it this way, each of them ripens at slightly different times. Not only do I get gallons of fruit from these bushes every season, but I also get fruit for two months straight.
But there’s another reason why planting cultivars with different ripening times can be advantageous. Late freezes can hurt your bushes, like they did to mine twice in 2021. The early season cultivar may be the only one that is hurt, but the later ones will still give you a big harvest.
Want to know which cultivars will grow best in your area? Read this post about growing blueberries in pots or the ground to find out more. ).
Why I don’t prune my blueberries- Small blueberry bush with lots of baby blueberries
FAQ
How do you increase the size of blueberries?
How to make blueberries grow bigger?
Why are my blueberries not getting big?
Why are my blueberries getting smaller?
Why are my berries so small?
Although there are many reasons for small berries including drought and variety selection, a common cause relates to pollination. Poor weather during flowering may inhibit bee flight, causing too few seeds to be produced. Seed number is proportional to berry size. Other causes include:
Why are my blueberries small?
The size of your blueberries can reveal a lot about the health of your plants and the conditions in which they are growing. If my blueberries are small, it could be a sign of various cultural or environmental issues, such as incorrect soil pH, inadequate watering, poor pollination, insufficient nutrients, or lack of proper pruning.
Why do blueberries shrivel up?
Berries are very few, tiny, tiny and then shrivel up. Some leaves on plants are rust-colored and dried up. Some branches are withering too. There are several problems that can contribute to these symptoms in blueberries. They are shallow-rooted plants and they are sensitive to soil pH, drought stress, and winter injury.
Why are my blueberries withering?
Some branches are withering too. There are several problems that can contribute to these symptoms in blueberries. They are shallow-rooted plants and they are sensitive to soil pH, drought stress, and winter injury. They can get stem and twig cankers and a disease called mummy berry. Have you had the soil tested?