Few gardening rewards can be as sweet as the delicious raspberry. Under the right conditions, a healthy raspberry bush can continue treating you to harvests for years. But if your raspberries aren’t ripening properly, you’ll want to know what you can do to fix it.
Raspberries failing to ripen can be due to incorrect soil conditions, irregular watering, lack of sun, garden pests, or various types of fungal diseases damaging the plant.
Fortunately, there are a number of things you can do as a gardener to help remedy these issues.
In this article, we’ll take a closer look at some of the most common causes of raspberry fruit not ripening fully. We’ll also be covering some simple, home solutions you can try in order to get your harvest back on track!
Incorrect Soil Conditions Prevent Raspberries from Ripening
Like many fruit-bearing bushes, raspberries require a steady feed of nutrients in order to thrive. They are relatively hungry feeders, particularly if you want to rely on them for a healthy, fat harvest year on year.
Raspberries will stand the best chance of ripening if the bush is raised in garden beds full of rich, fertile, well-draining soil. When first planting your raspberry bush outside, it’s advisable to dig plenty of well-rotted manure into your chosen garden bed. If possible, aim to add at least a bucket per square meter.
If your soil is particularly nutrient deficient prior to the raspberry bushes first being put in, it’s also worth considering adding a general-purpose, slow-release fertilizer like this one to the soil.
In early spring, consider adding a high potassium organic fertilizer to help the plant with healthy fruit production. Adding mulch or homemade garden compost to the soil will also help to gradually feed the plant throughout the growing season. This can simultaneously suppress weeds and retain moisture too.
If you’re growing your raspberries in containers, be careful that they don’t drain the limited soil they have available to them of nutrients. If they do, you may notice mishappen or shriveled fruit. It’s a good idea to add general-purpose fertilizer once a month to raspberry bush containers.
Too much nitrogen in the soil can be counterproductive. Your raspberry bush is likely to prioritize green, leafy growth over fruit production if it has a surplus of nitrogen at hand. This is why it’s important to ensure you are using balanced fertilizer to aid with fruit ripening. If in doubt, why not test out the nutrient balance of your soil using a home test kit?
Finally, raspberries prefer soil that is slightly acidic, preferably with a pH of between 6 and 6.5. Adding compost to your soil can help tip the pH in the right direction, as can pine needle mulch, cottonseed meal mulch, or leaf mold.
Irregular Watering Prevents Raspberries from Ripening
A common cause of raspberry fruit failing to ripen is a lack of regular watering. Raspberries, particularly during the height of the growing season, need consistently moist soil. Juicy, ripe berries need to get their water from somewhere!
Try to ensure you are keeping the soil moist but not saturated. When watering, make sure water is added below the leaf line and that the raspberry plant is kept as dry as possible. This can help discourage the development of fungal diseases, an issue we will soon be covering.
Raspberry bushes do great with drip irrigation or leaky hose irrigation. These watering systems can be ideal in making sure your bushes get irrigated at the base, whilst ensuring that the ground is kept consistently moist during dry periods.
To maximize the chance of your raspberries ripening properly, avoid irregular, sudden bouts of watering if at all possible. Periods of comparative drought interspersed with heavy watering spells are liable to stress the plant. This can affect its ability to produce and properly ripen fruit.
Lack of Sun Prevents Raspberries from Ripening Properly
Although raspberry bushes can survive and even produce fruit in partial shade, the best results are always going to come from the full sun. In order for your raspberries to have the best chance of ripening, they want a minimum of 6 hours a day, ideally more.
As well as choosing a good, sunny spot to plant your raspberry bushes in, think about the direction of your rows. It can be a good idea to position your rows north to south. This way your plants, which are likely to grow tall and bushy with the correct supports, are less liable to shade one another.
Garden Pests Can Feed on Raspberries Before They Ripen
We humans aren’t the only ones partial to a sweet raspberry. There are, unfortunately, a whole host of hungry critters liable to chomp on your raspberries before they have ripened fully. If this is the case, you may notice your raspberries becoming shriveled (or even vanishing) before they’ve had a chance to reach maturity.
This is a common culprit when it comes to raspberries failing to ripen. You may notice dry patches appearing at the stalk end of the raspberry, particularly in the middle of summer. The raspberry itself will often turn shriveled and fail to properly fatten. If you open up the fruit, you may find a small, white maggot inside.
Small numbers of raspberry beetles can often be tolerated on a large, healthy raspberry bush. However, inspecting plants regularly and removing affected berries by hand as soon as possible can be key in keeping any burgeoning infestation in check.
Furthermore, autumn fruiting varieties of raspberry tend to be less susceptible to this particular pest. Making sure you have some autumn fruiting varieties in your patch can help diversify and extend your harvest.
If your raspberry bush is being plucked bare before the fruit has a chance to ripen, it could be the work of birds. The most reliable method of keeping these winged diners away from your crop is through nets like this one. Bird scarers and other preventative methods tend to be less consistent in their effects, or may only work for a short period.
When placing bird netting to protect your crops, ensure that the netting itself doesn’t rest on the bush where the fruit is being produced. If it does, birds will simply get their beaks in between the netting and can continue to munch on your raspberries.
Fungal Diseases Can Damage Your Raspberry Bush and Prevent Fruit from Ripening
Raspberry bushes can be susceptible to a range of fungal diseases, some of which can regrettably spell the end of your plant. Most fungal diseases will, even if they do not kill the raspberry plant, hinder its ability to produce healthy, fully ripe fruit.
Orange Rust Disease
This form of fungal growth primarily affects purple raspberry bushes. Red raspberry varieties are often resistant.
You may notice orange spots appearing on leaves, or orange-yellow bumps cropping up on the underside of foliage.
Orange rust disease can hamper your plant’s ability to produce and ripen fruit. Once it takes hold it can also be difficult to get your plant to return to full health. Pruning and destroying affected parts can help slow the spread, but are unlikely to stop it entirely.
As with all fungal diseases, prevention is often more effective than post-symptomatic treatment. Try to ensure your raspberry bed is kept clear of weeds, is well aerated, and that plant foliage is not left damp for extended periods.
This is commonly caused by an excess of water in poorly draining soil. If your raspberry roots are left saturated, this can result in a fungal growth that effectively causes them to rot.
Fruit failure to develop properly can be one of the early signs of this disease. Leaves turning red, yellow, or purple can also be a symptom. Above-ground symptoms are, however, sometimes not possible to spot until it’s too late, with the disease really taking root below the surface.
Ensuring that your raspberries are in well-draining soil and not overwatered is important in preventing root rot. Drip irrigation can help regulate the moisture in the soil without drowning the plant.
During the summer months, cane blight can appear as the base of raspberry canes becomes dark or brittle. Some of the canes may snap easily. Fruit on these canes will often struggle to ripen properly. Purple or dark spots may also appear on foliage or stems.
Stressed, thirsty plants are more susceptible to this type of disease. Regular watering is important in making sure they are healthy and resilient. Well-aerated regularly weeded beds will also help ensure foliage and plants remain relatively dry above ground. This is important in helping prevent cane blight from developing.