Growing juicy plump blackberries is a dream for many gardeners. However it can be incredibly frustrating when your blackberry bush blooms yet produces little to no fruit. If you’ve nurtured your blackberry plant but it still refuses to bear berries, don’t lose hope! There are several common reasons why a blackberry bush may not fruit, but the problem can often be corrected with a few simple fixes.
Common Causes of Blackberries Not Fruiting
When blackberry bushes don’t have any fruit, these 10 things are most often to blame.
1. Viral Infection
Blackberries are prone to viral diseases like blackberry calico, tobacco ringspot virus, and black raspberry streak virus. Unfortunately, these viruses rarely display outward symptoms other than reduced yields. Infected plants may even appear more vigorous as the virus diverts energy from fruiting to vegetative growth. Viral infections cannot be cured so infected plants should be dug up, destroyed, and replaced with certified virus-free stock.
2. Fungal Disease
Fungal diseases, such as anthracnose, can stop blackberry bushes from producing fruit. Infected berries shrivel up and rot before fully ripening. Cut off and destroy any canes that are infected, and then use a fungicide on the plants. Improve airflow and sunlight exposure to discourage fungal disease development.
3. Insufficient Pollination
Blackberries must be pollinated by bees, butterflies and other insects to produce berries. Avoid applying insecticides during bloom time. Plant pollinator-friendly flowers nearby to attract more pollinators. Hand pollination is an option if natural pollination is inadequate.
4. Nutrient Deficiencies
Blackberries need proper nutrition to support growth and fruiting. Deficiencies in nitrogen, phosphorus, potassium, magnesium, iron or zinc can all limit yields. Have your soil tested and amend as needed based on recommendations. Mulch annually with compost. Foliar feeding can also provide a nutrient boost.
5. Inadequate Sunlight
Blackberries require full sun – at least 6-8 hours of direct sun per day. Bushes in too much shade or crowded by other plants won’t get enough light to fruit well. Prune or transplant blackberries to a sunnier location. Container-grown plants should be moved to the brightest spot possible.
6. Unfavorable Weather
Extreme weather can interfere with pollination and cause flower/fruit loss. Frost can damage blossoms. Excess heat can cause flowers and berries to abort or dry up. Erratic rainfall when berries are ripening causes problems. Select suitable varieties and provide proper care to help bushes tolerate weather fluctuations.
7. Improper Pruning
If you prune blackberries at the wrong time, you cut off the canes that would bear fruit. Blackberries fruit on 2-year-old floricanes. Primocanes from this season shouldn’t be pruned until late winter, when they are dormant. To help new primocanes grow, only remove old floricanes that have already produced fruit.
8. Root Damage
Root damage from diseases, nematodes, poor drainage, drought stress, or changes in cultivation can make it harder to grow fruit. Fix drainage problems, be careful not to hurt the roots when you’re planting, and make sure the bushes get enough water.
9. Poor Variety Selection
Some varieties naturally produce poorer yields. Erect blackberries like ‘Navaho’ tend to be heavier bearing than semi-erect or trailing types like ‘Marion’. Consider replanting with a more productive variety if yields are chronically disappointing.
10. Old Canes
Mature canes over 3 years old produce little fruit. Canes should be renewed by pruning out old floricanes after harvest. This stimulates new vigorous primocanes to develop each year. Allowing old declining canes to remain leads to diminished yields.
How to Get Your Blackberry Bush to Fruit
Once you’ve diagnosed the likely cause of your blackberry bush not fruiting, you can take action to get your plants producing again:
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Replace virus-infected plants and ensure new plants are certified virus-free.
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Apply fungicides to control diseases. Improve airflow and prune for better sun exposure.
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Avoid insecticides during bloom. Hand pollinate flowers if needed. Plant flowers to attract pollinators.
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Amend soil and foliar feed to correct nutrient deficiencies. Test soil to determine specific needs.
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Transplant or aggressively prune adjacent plants shading the blackberries.
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Select varieties suited for your climate. Provide wind protection, extra mulch, or irrigation as needed.
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Learn proper pruning timing and techniques. Remove only old floricanes, never current season primocanes.
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Improve drainage and irrigation. Avoid cultivating around roots.
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Switch to a productive erect blackberry variety suited for your region.
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Annually prune out floricanes older than 2 years. Train primocanes to replace them.
With a bit of detective work and attentive care, your unfruitful blackberry bush can be coaxed into producing sweet, juicy blackberries. Pay close attention to bloom and fruit development. Address issues promptly to get your plants back on track. With the right solutions applied, you’ll be rewarded with abundant blackberry harvests.
Starting Plants: Canes vs. Seeds
It’s much simpler to start your blackberries from canes or nursery plants than from seeds, and you’ll get fruit much faster. You can get bare-root or flowering canes from a nursery. You can also get canes from your neighbor, or pull wild ones from one part of your yard into another. However, I strongly recommend starting your blackberries with nursery plants. Why?.
Getting your plants from a reputable nursery means you’ll know the precise variety and characteristics of your blackberry. If you take canes from your neighbor Joe, you’ll probably get blackberries, but they may be hybrids with other nearby plants, or prone to disease. Nursery canes are usually sterile (as in, disease-free) and tend to grow bigger, sweeter fruits. I also really hate thorns, and blackberry picking is already labor-intensive enough without dodging stems that tear up my hands, so I love our thornless varieties that we got from our cool local nursery.
Something to note: your nursery blackberry plants are likely a graft (that is, the blackberry plant is attached to another similar plant to enhance the coolest parts of a blackberry), so if that’s a concern, go ahead and go the wild route. Or just ask about the plant you’re getting. However, I’m a fan of the grafts, if you can’t tell.
You can also grow canes from seeds, but it will take a lot longer than growing canes. Also, keep in mind that many blackberry plants are actually hybrids or grafts, so the blackberry you choose may not even produce fruits or fruits that are similar to those you planted.
Okay, let’s plant these buggers. You’ve got your canes. Now what?
As I mentioned before, blackberries have very shallow roots, so you don’t need to plant them very deep. You do, however, want to clear the planting area of grass and other competing plants, because of those shallow roots. To stop this competition, I suggest using sheet mulch and making sure the growing area stays well-mulched every season. Also, avoid tall grass that could hide animals that like to hang out near blackberries, like mice and snakes.
Plant the canes maybe an inch deeper than the nursery container, making sure the roots are completely covered, but not so deep that the cane disappears. Plant canes 5-6 feet apart, at least, and keep rows 5-8 feet apart.
Blackberries can grow in a lot of different types of soil, even poor clay soil. However, they do best with compost added to the soil, soil that is less dense than clay, mulching, and most importantly, good drainage. Blackberries will not thrive with wet feet.
Lifting, Pruning, and Cultivating
You’ve successfully planted your main berry brambles, and they’re alive. Hooray! Now what?
In the first year, it’s super important that you do. Not. Let your blackberries produce fruit.
I explain this in more detail in my Pruning post, but the gist is that by pruning the flowers the first year, you allow the main plant focus its energy on establishing good roots, as well as more canes for the coming years. For reference, with good pruning, cutting, and cultivating practices, your blackberry bramble can show this progression:
Okay. You’ve planted your canes. You pruned the flowers in the first year. It’s the second year, and your canes are now bursting with blackberry fruits. Major huzzah!
Your fruits will go from from green and hard, to red and softer, to a dark, nearly black (hence the name) purple and fairly soft.
Blackberries do not continue to ripen after harvest, so be sure to pick fruits that have entirely changed their final color. They also rot super fast on the plant after fully ripening (as in, within a couple of days, and less time when it’s very hot or rainy), so make sure you’re checking your bramble every day for fruit.
Pull berries very gently from the plant (ripe ones should give easily), and try not to disturb the rest of the cane, lest you accidentally knock other berries to the ground, or tear the plant.
Some things to watch out for on and around your blackberries:
- Birds. Birds love berries so much! To keep birds from eating your bramble, drape it with bird netting. We’ve used this before and it works, but it’s a pain to take down at the end of the season because it gets tangled up with the plant, and it’s not good to throw away. Keeping other, more appealing plants and leaving them for the birds is another option. That’s why we leave wild blackberries on the edges of our property. You can also beat the birds at their own game by picking your blackberries early every day.
- Stinkbugs and Junebugs. You’ll run into these guys every time you harvest. They won’t harm you, but they’ll chomp on your berries. We get a good harvest, so I don’t use any pesticides on them. I just kind of live with them and the scream I let out every once in a while when I pick a junebug instead of a berry.
- Mice and Snakes. Thus far, these two animals have not caused us any harm. However, they might if you let the grass grow too high around your bushes or if you don’t pick your berries quickly enough before they fall to the ground. (Dropped berries can attract mice, which then attract snakes. Just in case, make sure to wear closed shoes and long pants when you harvest.
- Yellow Jackets, Wasps, etc. Yet another reason to always wear boots. There is a chance that these bugs will hang out and even build a nest near your bramble if you leave holes and/or a lot of berries to rot on the ground. Keep the area cleared and filled in, and when picking berries, always wear clothes that will protect you.
- Thorns. If you’ve got a thorny variety, that is. There’s no doubt that those thorns can rip through skin as well as denim. I think you should wear long sleeves and gloves when picking berries from thorny canes.
How to Prune Blackberries the Right Way for Bigger Harvests
FAQ
Why are my blackberry bushes growing but not producing fruit?
Blackberries that don’t set fruit are likely sick with one or more virus diseases that affect the whole plant. Diseased plants produce new canes that are more vigorous, with rounded and glossier leaflets than normal. The leaves also develop a brilliant, premature reddening in the fall (Figure 1).
How to get blackberry bush to produce fruit?
Blackberry Production Checklist Build a trellis (can be done before or within first year of planting). Irrigate on a regular basis. Allow three to four new canes per plant to grow to the top wire. Harvest a baby crop of fruit one year after planting and a full crop two years after planting.
Do blackberry bushes produce fruit every year?
Yes, blackberry plants typically produce fruit every year after their first year. Blackberries are perennials, meaning their roots live for many years. However, the canes (the above-ground stems) are biennial, meaning they live for two years.
What’s wrong with my blackberry plant?
VIRUSES Can be identified by stunted canes and leaves which are mottled or streaked, usually yellow. Unfortunately there is no cure so all canes should be dug up and burnt. Replanting should occur as far away as possible to prevent the disease spreading to them.