Why Are My Blueberries So Small

If you’re asking “why are my blueberries so small,” you’re not alone. This common frustration has a few key causes, but the good news is that fixing them is straightforward. With some targeted care, you can encourage your bushes to produce the plump, juicy berries you’ve been hoping for.

Small berries are usually a sign that your plant is stressed or missing something it needs. It’s rarely just one thing. Think of it as your blueberry’s way of asking for a little more attention. Let’s look at the main reasons and how you can turn things around for a better harvest next season.

This heading covers the core problems. We’ll break each one down in detail next.

1. Not Enough Sunlight

Blueberries are sun lovers. They need full sun to produce their best and biggest fruit. “Full sun” means at least 6 to 8 hours of direct sunlight each day.

If your bush is shaded by trees, buildings, or even other plants, it won’t have the energy to swell its berries.
The plant will prioritize survival over fruit production, resulting in small, sour, or few berries.

Check the sun pattern in your garden. If needed, consider carefully transplanting the bush to a sunnier spot in late fall or early spring.

2. Incorrect Soil pH (The Biggest Culprit)

This is the most common mistake gardeners make. Blueberries require very acidic soil to thrive. The ideal pH range is between 4.5 and 5.5.

At a higher (more neutral) pH, the plant cannot access nutrients like iron, even if they are present in the soil. This is called nutrient lockout.
The bush becomes nutrient-deficient, leading to stunted growth, yellowing leaves, and tiny fruit.

Solution: Test your soil pH first. Don’t guess. You can use a home test kit or send a sample to an extension service. To lower pH, amend the soil with elemental sulfur or use an acidifying fertilizer. Coffee grounds are not strong enough to make a significant difference on their own.

3. Improper or Inadequate Watering

Blueberries have shallow, fine roots that dry out quickly. They need consistent moisture, especially during two critical periods: bloom time and when the fruits are swelling.

Letting the soil dry out completely during fruit development will absolutely result in small, shriveled berries. The plant simply can’t move enough water into the fruit.

However, they also hate “wet feet.” Soggy, poorly drained soil will cause root rot.

Aim for 1 to 2 inches of water per week, more during hot, dry spells. A layer of mulch is essential to help retain this soil moisture.

4. Lack of Proper Pruning

An overgrown, dense bush is a recipe for small berries. Without pruning, the plant produces too many berries for the energy it has, so all remain small. It also creates poor air circulation, inviting disease.

Pruning directs the plant’s energy into producing larger fruit on stronger canes. Here’s the basic approach:

Prune in late winter while the plant is dormant.
Remove any dead, damaged, or diseased wood first.
Cut out the oldest, thickest canes (more than 6 years old) at ground level to make room for new, productive growth.
Thin out weak, twiggy branches and any that cross through the center of the bush.
Aim for an open, vase-shaped structure that allows light and air into the middle.

5. Overbearing or Biennial Bearing

Sometimes a bush sets an enormous number of fruit buds. It physically cannot support them all to a large size. This is called overbearing.

Some varieties also have a tendency toward biennial bearing, meaning they produce a massive crop one year (with smaller fruit) and a very light crop the next.

Solution: Don’t be afraid to rub off some of the flower clusters in spring, especially on a young bush. This seems counterintuitive, but it allows the plant to focus its resources on fewer, high-quality berries. Thinning the fruit leads to much large individual sizes.

6. Nutrient Deficiencies

Even with the correct pH, blueberries need the right food. They are light feeders but have specific needs. A lack of key nutrients like nitrogen, potassium, or magnesium can limit fruit size.

Use a fertilizer formulated for acid-loving plants (like azalea/camellia fertilizer).
Apply fertilizer in early spring as growth begins and again lightly in late spring. Avoid fertilizing late in the season, as it can promote tender new growth that winter will damage.
Organic options like cottonseed meal or fish emulsion work very well.

7. Variety Matters

It’s important to have realistic expectations. Some blueberry varieties naturally produce smaller berries than others. For example, wild “lowbush” types have tiny, flavorful berries, while cultivated “highbush” varieties are bred for size.

If you planted a variety known for medium-sized fruit, no amount of care will make it produce giant berries. Research your specific variety to know what’s normal.

8. Pollination Issues

While many blueberries are self-fertile, they will produce a much better and larger crop with cross-pollination. Having at least two different varieties that bloom at the same time ensures better pollination.

More complete pollination leads to more seeds in each berry. And more seeds often triggers the plant to produce a larger fruit around them. If you only have one lonely bush, planting a companion can make a huge difference.

Your Action Plan for Bigger Blueberries

Start with these steps in order. Don’t try to do everything at once if your bush is established.

Test Your Soil pH. This is non-negotiable. Amend with sulfur if needed. It can take months to adjust, so be patient.
Improve Your Watering Routine. Set up a soaker hose or drip irrigation under a thick layer of acidic mulch like pine bark or wood chips. This keeps moisture consistent.
Prune Correctly and Annually. Take the time in late winter. It feels scary at first, but your bush will thank you with vigor.
Fertilize Appropriately. Use an acid-loving plant food in spring, following label rates. More is not better.
Consider Plant Age and Variety. Young bushes (under 3 years) often produce small fruit as they establish. Also, make sure you have a variety known for good-sized berries if that’s your goal.

FAQ: Blueberry Growing Problems

Q: Why are my blueberries staying small and not ripening?
A: This is almost always due to lack of sun or incorrect soil pH. The plant lacks the energy and nutrients to complete the ripening process. Test your pH and evaluate sunlight hours.

Q: How can I make my blueberries grow bigger?
A: Follow the action plan above. Focus on soil acidity, consistent watering, and annual pruning. Ensuring good pollination by planting another variety nearby also helps.

Q: What is the best fertilizer for larger blueberries?
A. A fertilizer for acid-loving plants (e.g., 10-10-10 or similar) is best. Organic options like blood meal (for nitrogen) or sulfate of potash (for potassium) can be used to address specific deficiencies shown in a soil test.

Q: Should I remove small blueberries from the bush?
A: Yes, if the bush is very young (first two years) or is overladen with fruit. Removing some green berries allows the plant to direct energy into growing the remaining fruit larger and establishing a stronger root system.

Q: Do blueberries need a lot of water to get big?
A: They need consistent moisture. Big berries are full of water, so drought stress during fruit swell will absolutely limit their size. Deep watering is better than frequent light sprinklings.

Growing plump, generous blueberries is a very achievable goal. It comes down to understanding their specific needs: acidic soil, consistent water, full sun, and regular pruning. Start by investigating the most likely culprit—soil pH—and go from there. With a few adjustments this season, you can look forward to a noticeably improved harvest next summer.