Raspberry Bush Flowers, But No Fruit? Causes & Solutions


If you have raspberry bushes, you know that there is nothing more frustrating than getting flowers on your canes, but no fruit at all.  I did some research and found some answers for this problem, which I’ll share below.

So, why is your raspberry bush flowering, but producing no fruit?  A raspberry bush will flower, but produce no fruit, if proper pollination does not occur.  You can use an electric toothbrush to simulate a bee’s movement and touch it to the flowers on your raspberry bush to pollinate them.

Also, keep in mind that for summer-bearing varieties, raspberry canes will not produce any fruit in their first year.  Temperature, soil problems, and nutrient deficiencies could also play a role in a lack of fruit production.

It can be a little confusing to sift through all of the information on raspberry varieties, pollination, and other factors that affect fruit production.  Let’s start off with an explanation of the types of raspberries you can grow and when you should expect fruit.

Then, we’ll get into the factors that can prevent fruiting on your raspberry bush, along with ways to address each problem.

When Should Your Raspberries Produce Fruit?

Patience is the name of the game here!  After you begin to see flowers on your raspberry bush (in late May or early June), it may take a month or longer before you begin to see the first fruit.

raspberries
Delicious, ripe, red raspberries.

Of course, when a raspberry cane produces fruit – and whether it produces fruit at all – will depend on a couple of factors.  The first factor is the age of the raspberry cane, and the second factor is the variety of raspberry you are growing.

Raspberry Canes: Primocanes and Floricanes

Raspberry plants have two types of canes (think stalks or stems): primocanes and floricanes.

raspberry bush
Raspberry canes, some of which are fruiting.

Primocanes are “first-year” canes, and they are the new growth canes that come from the plant.  They look green and fleshy.  Normally, these first-year canes produce no fruit.

Floricanes are “second-year” canes, and they are the canes that appeared last year and are going into their second year.  They look brown and woody.  Normally, floricanes are the only canes that produce fruit (usually in early to mid-summer).  After the second year, the floricanes die and can be pruned away.

Raspberry Bushes: Summer-bearing and Ever-bearing

This means that if you planted a traditional (summer-bearing) new raspberry bush in your yard, you would not get any fruit in the first year.

However, thanks to the wonders of modern agriculture, science has bred primocane-fruiting raspberry bushes (also called ever-bearing or fall-bearing).  The canes of these raspberry bushes produce fruit twice.

The first harvest is from flowers at the tips of the canes, in the first year (usually in mid to late summer or early fall).  The second harvest is from the lower parts of the canes, in the summer of the second year.

The take-home message is this: if you plant a new raspberry bush in your yard that is not primocane-fruiting, then the new canes will not fruit at all in the first year.

Assuming that you have ever-bearing raspberry bushes or summer-bearing bushes with some second-year canes, you should be getting fruit from your flowers.  Otherwise, something is wrong.  Let’s explore the potential problems that can prevent fruiting, and how to solve them.

Lack of Pollination

It is important to remember that raspberries are self-pollinating.  That is, a flower on a raspberry bush contains both male and female parts.

Under ideal conditions, the male part releases pollen onto the female part, and a fruit (raspberry) will form.  This means that you only need one raspberry bush in order for the flowers to pollinate and produce fruit.

However, it is also important to remember that self-pollination does not mean automatic pollination.  There are still certain conditions that need to be met in order for the flowers of a raspberry bush to self-pollinate.

Extreme Weather

First of all, extreme humidity can prevent the flowers on a raspberry bush from self-pollinating.  High humidity will make the pollen sticky, meaning that the male part of the flower cannot release it onto the female part.

Low humidity will make the pollen too dry, meaning that it will not stick to the female part of the flower, even after the male part releases the pollen.

Also, incorrect temperatures will delay the fruiting of raspberry bushes.  The ideal daytime temperature range for growing raspberries is 70 to 75 degrees Fahrenheit.  If temperatures get much higher than this, the pollen from the male part of the flower will not be available.

Before you begin planting raspberries, it is a good idea to check the USDA Zone Hardiness Map.  That way, you can tell whether you should go for ever-bearing raspberries, whose canes do not need to survive the winter to give you a crop of fruit.

Most gardening or nursery websites that sell raspberry bushes will tell you the ideal plant hardiness zones for each specific variety.

Lack of Pollinators

A lack of pollinators will also prevent the flowers on a raspberry plant from fruiting.  Bees are the most common pollinator, but their population in many areas has been devastated in recent years.  Often, pesticides are to blame, so if you are using them, try to cut down.

bee on blueberry flower
This bee will pollinate your flowers, unless you repel him with pesticides!

You may notice that other plants in your yard are fruiting, but the raspberries are not.  In that case, one solution is to plant attractive flowers near your raspberries.  That way, the bees have a reason to stop by.  Hopefully, they will pollinate the raspberries while they are in the area.

Another solution is to use an electric toothbrush on each of the flowers on your raspberry bush.  This vibration simulates a bee’s vibrating wings, and will cause the male part of the flower to release pollen onto the female part.  It is best to repeat this process every day or two for the best possible raspberry yield.

Poor Soil Conditions

If the pollination conditions (heat, humidity, and bees) are right for pollination, you can still have improper soil conditions for raspberries to fruit.

Soil pH

First, you should make sure the soil around your raspberry bush has the proper pH (a pH of 7.0 is neutral).  An ideal pH for raspberry bushes is 5.5 to 6.5, which is slightly acidic (more so than most vegetables prefer).  Proper pH is essential for your plants to be able to absorb nutrients from the soil through their roots.

You can test the pH of your soil with a home soil test kit, available online or at a garden center.  You can also contact your local agricultural extension to request soil testing. To learn more, check out my article on soil testing.

If the soil pH is too high, you can lower the pH by adding elemental sulfur or iron sulfate.  As an added benefit, sulfur and iron are both necessary nutrients for plants to grow. For more information, check out my article on how to lower your soil pH.

If the soil pH is too low, you can raise the pH by adding lime, which contains calcium, another necessary nutrient for plant growth. For more information, check out my article on raising your soil pH.  One caution: adding too much calcium to your soil can prevent your plants from absorbing magnesium (calcium and magnesium “compete” for uptake by the plant’s roots).

Nutrient Deficiencies

Second, you also need to determine whether your raspberry bush is suffering from some sort of nutrient deficiency.  Usually, other parts of the plant will show signs of nutrient deficiency, such as yellow leaves.

Nitrogen, phosphorus, and potassium (N-P-K) are the most common nutrients in fertilizers, but they could still be deficient.  If your plants are deficient in nitrogen, phosphorus, or potassium, you can find specific fertilizers that will supplement these nutrients. For more information on these three important plant nutrients, check out my article on the NPK ratio.

Other important nutrients are calcium, iron, and magnesium.  You can use the following supplements for these nutrient deficiencies:

  • Calcium: use lime (calcium carbonate)
  • Iron: chelated iron
  • Magnesium: Epsom salt (magnesium sulfate)
magnesium sulfate
Epsom salt, or magnesium sulfate, is a common garden supplement.

Even a lack of trace elements, such as zinc, boron, molybdenum, or manganese, can cause problems.  The best way to find out about a nutrient deficiency is to get a soil test.

As mentioned earlier, a nutrient imbalance can also cause problems for your plant.  For instance, too much potassium can prevent a plant from absorbing calcium or magnesium, even if there are plenty of those nutrients in the soil.

Of course, a great way to supplement almost every nutrient your plants need is good old-fashioned compost made from leaves, grass, and food scraps (not meat!)

Other Problems

There are a few other problems to look out for if your raspberry bushes have flowers, but no fruit. Let’s take them one at a time.

Location

Where you plant your raspberry bushes will impact how well they do, and whether they fruit at all.  Raspberries like full sun, so don’t plant them in a shady area.

sunlight through forest
Let there be light.

Even if the spot was originally sunny, overhanging tree branches can block out light for part of the day, and you might not notice while you are at work.

You should also make sure that your soil has good drainage (clay soils do not drain well).  To test this, dig a hole and pour water into it.  If it takes more than ten minutes to drain away, then the soil drains poorly.

If your soil drains poorly, one way to improve drainage is to mix organic material, such as compost, into your soil.  This has the added benefit of adding nutrients to the soil.

If you struggle with dry soil, check out my article on how to treat dry soil.

Pests

Believe it or not, pests could actually be to blame for a lack of fruit on your berry bushes.  A friend of mine woke up one morning to find all of the fruit gone from one of his berry bushes – as high as 6 feet up on the plant!

raspberries
A pest could easily eat the raspberries from this bush, which is close to the ground.

I thought a deer could have done the damage, and if they get hungry enough, they may eat the flowers before they have a chance to ripen.

Old Canes

Everything has a lifespan, including raspberry bushes.  A cane only lives for two years, but a raspberry bush can last 15 years or more, producing new canes (primocanes) each year.

If your plant is getting up to that age (or if it’s been so long that you can’t remember when you planted it!), then you might need to consider some new raspberry bushes for your yard.

Diseases

It is possible that a disease could prevent your raspberry bush from setting fruit, even when it flowers.  However, you will likely see other signs of disease in the flowers, leaves, or stems. For more information, check out my article on why your raspberry canes are dying.

If the plant looks healthy otherwise, then a disease seems unlikely.

Conclusion

By now, you should have a better idea of what could be preventing your raspberry bushes from producing fruit.  Hopefully, you can find the exact cause and solve the problem so that you can start harvesting raspberries in the near future.

I hope this article was helpful.  If you have any questions or advice that worked for you, please let me know in the comments below.

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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