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If your blackberries are small, the reason usually comes down to one of a few common growing problems, and the good news is that most of them are easy to fix.
Small blackberries can happen for lots of reasons, from a lack of water and sunlight to poor pruning, nutrient imbalances, or simply the age of your canes.
The size of your blackberries often tells you exactly what the plant is trying to tell you.
In this post, we’ll walk through why your blackberries are small, what causes tiny fruit, and how to get bigger, juicier berries next season.
Let’s dig in.
Why Your Blackberries Are Small
Blackberries are small for a handful of very specific reasons, and once you know what to look for, you can usually trace the problem back to just one or two culprits.
Here’s a breakdown of the most common causes.
1. Not Enough Water
Blackberries need consistent moisture, especially while the fruit is swelling and ripening.
If your plants are drought-stressed during that window, the berries simply won’t size up, no matter how healthy the rest of the plant looks.
Small blackberries are often the first sign that your plants are thirsty.
Aim for about an inch of water per week, either from rain or from deep, slow watering at the base of the plant.
2. Too Much Shade
Blackberries are sun lovers, and they need at least six to eight hours of direct sunlight every day to produce fruit that’s worth picking.
When blackberries are grown in too much shade, the plant puts its energy into reaching for light instead of plumping up the berries.
That’s why small blackberries almost always show up on canes that are crowded or shaded by trees, fences, or other plants.
3. Poor Pruning Habits
Blackberries fruit on canes that are one year old, which means last year’s growth is what gives you this year’s harvest.
If you’re not pruning out the old, spent canes, your plant wastes energy on wood that will never fruit again.
That wasted energy is energy that should be going into making your blackberries bigger.
Prune out the canes that already fruited as soon as the season ends, and thin the new canes so air and light can move through the patch.
4. Nutrient Problems in the Soil
Blackberries are heavy feeders, and when they’re low on key nutrients, one of the first symptoms is small fruit.
A lack of phosphorus or potassium can lead to blackberries that stay small and never reach their full size.
On the flip side, too much nitrogen gives you a big, leafy plant with lots of green growth but tiny berries.
A soil test is the fastest way to find out what your blackberries are actually missing.
Other Reasons Blackberries Stay Small
Beyond water, sun, pruning, and nutrients, there are a few more reasons your blackberries might be smaller than you’d like.
1. The Variety You’re Growing
Some blackberry varieties just naturally produce smaller fruit than others.
If you’re growing a wild or heirloom type, small blackberries may simply be what that plant does.
Varieties like ‘Chester’ or ‘Triple Crown’ are known for producing large, sweet berries, so if size matters to you, that’s worth keeping in mind.
2. Pests and Disease
Insects like spider mites and diseases like orange rust can sap a plant’s strength and leave you with a crop of small blackberries.
Check the undersides of leaves and the new growth for signs of trouble, and treat problems early before they spread.
3. Plants That Are Too Young or Too Old
A first-year blackberry plant often gives you small fruit because it’s still establishing its root system.
Older patches that haven’t been renewed in years can also produce small blackberries as the plants run out of steam.
Sometimes the fix is as simple as patience, and sometimes it’s time to replant.
4. Overcrowded Canes
When blackberry canes are packed too tightly, they compete for water, nutrients, and sunlight.
That competition is a recipe for small blackberries across the whole patch.
Thin your canes to about four to six strong ones per plant, and you’ll notice the difference in berry size.
How to Get Bigger Blackberries Next Season
If you want to fix small blackberries, the plan is pretty straightforward.
Water deeply and consistently, especially during fruiting.
Make sure your plants get full sun and aren’t crowded by other canes or nearby trees.
Feed with a balanced fertilizer in early spring, and avoid pushing too much nitrogen.
Prune out old canes after harvest and thin the new ones so the patch can breathe.
Mulch around the base to hold moisture and keep weeds down.
Do those things consistently, and your blackberries should size up season after season.
So, Why Are My Blackberries Small?
Blackberries are small because of things like inconsistent watering, too much shade, poor pruning, nutrient imbalances, pests, or simply the variety and age of your plants.
The good news is that small blackberries are rarely a permanent problem.
Once you give your plants the water, sunlight, food, and space they need, those tiny berries turn into the big, sweet fruit you were hoping for.
So take a closer look at your patch this week, fix what’s off, and get ready for a better harvest next time.