My Blueberries Are Sour: How To Sweeten Sour Blueberries

Bowl Full Of Blueberries Surrounded By Green Leaves
blueberry fruit
(Image credit: KishiPhoto)

When you pop freshly-picked blueberries into your mouth expecting sweet, delicious fruit, then sour blueberry fruit is a great disappointment. Unless you’ve selected tart berry cultivars, altering your care and harvest of blueberries may solve the problem. Read on to learn why blueberries are sour and what to do with sour blueberries.

What Makes Blueberries Sour?

The first thing to do when garden blueberries are sour is to determine the characteristics of the cultivar you have chosen. With hundreds of types of blueberries available, the cultivar fruit taste can vary from tart to sweet. If your bushes are intended to produce tart or sour fruit, you may want to select new cultivars. A common cause of sour blueberry fruit is over-production on a bush. If your bush is newly planted, you’ll get sweeter, bigger berries if you remove all blossoms for the first year or two to allow the root system to establish. Even mature blueberry bushes can over produce some years and, if left to their own devices, produce abundant but sour fruit. Keep your eye on buds and thin back when needed. Let your berries ripen on the bush. It is not a good idea to pick berries early. Even if you can get sour blueberry fruit to soften by storing them beside apples or bananas, they will not sweeten any further. If blueberries are sour when picked, they will remain so. You can’t sweeten sour blueberries once you take them from the bush. Try eating a few berries before beginning your harvest and remember that all berries do not ripen simultaneously. Even in one cluster, some may be ripe and some unripe. Identify unripe berries by the reddish hue, but even solid blue berries need to stay on the bush for a few days before they develop true sweetness. Waiting is a good way to sweeten sour blueberries. Blueberries can remain on the bush for 10 days after they begin to ripen, so don’t be in a hurry. The fruit size and sweetness increase very quickly at the end of the ripening process. Ensuring that your blueberry plants are grown in acidic soil and keeping them fertilized annually will also help to sweeten the blueberries.

What to Do With Sour Berries

If you’ve already harvested your blueberry fruit, you may be asking what to do with sour berries that haven’t fully ripened. Placing the berries in a paper bag and storing them in a cool place will allow the fruit to ripen. If you add an applebanana, or avocado to the bag, the berries ripen more quickly. Keep in mind that this will soften immature berries, but it will not sweeten sour berries. If you want to cook with the berries, just add extra sugar or honey.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.