Picking sloe berries: when are sloes ripe?

It is not just birds that enjoy sloe berries, we can also benefit from the fruit. Discover when and how to harvest sloes and what to do with the berries.

Sloes (Prunus spinosa) can often be found growing wild on roadsides, slopes or in hedgerows. Birds love the dark blue berries and find plenty of food on blackthorn bushes in autumn. But it is not only our feathered friends that make use of the healthy sloe berry. Here, we tell you when it is best to harvest sloes, how to go about it and what delicious treats can be made from them.

When are sloes ready to pick?

The best time to pick sloes is when they are ripe. In autumn, their skins turn a deep blue-black up to the base of the stalk, and it is a good idea to harvest the fruit then, before the birds have picked them all! Unfortunately, the berries will still be bitter at this time, and contain a lot of tannins, which impacts their taste.

Fortunately, this all changes after the first frost. Once the fruits freeze, their cell walls become more permeable, their starch converts to sugar, and their tannin content decreases. As a result, the fruits taste milder. Sloes are at their tastiest, for birds and for people, between the end of November and mid-December.

As such, the best thing to do is harvest the fruits in autumn and then put them in the freezer. This way, you get the best of both worlds: harvest the fruit before the birds have eaten them all, and enjoy the berries’ mild taste by creating an artificial frost.

Harvesting sloes: how to pick sloes

Sloe bushes are not called blackthorn for nothing. Their branches are very prickly and covered with thorns. This makes picking sloes a little tricky. It is a good idea to wear gloves and long-sleeved clothing when harvesting sloe berries. Simply pick the berries individually from the branches.

Can you eat sloes raw?

You may have heard the rumour that sloe berries are poisonous when raw. However, this is only partly true. You can eat raw sloes, but only in moderation. The seeds of the sloe contain amygdalin, which the body converts to prussic acid, a very toxic substance for humans. However, there is only a small amount of amygdalin in sloe berry seeds, so you would have to eat a huge quantity to get poisoned.

Caution: For children, eating sloes raw is dangerous, because children are unable to digest the prussic acid. Sloe berries can cause nausea, vomiting and diarrhoea in children and should be avoided at all costs.

Although adults can eat raw sloes safely in small quantities, many people choose not to eat raw sloes because of their bitter taste, especially when the fruits are eaten pre-frost. However, it is worth eating raw sloes, if not for the taste, as they are said to have antioxidant, anti-inflammatory, stomach-calming and digestive properties.

Drying and freezing sloes

Sloes only keep for a few days, so it is a good idea to process your harvest as soon as possible. An easy way to preserve sloes is to dry or freeze them. It is best to dry sloes in an oven at a low temperature, or in a dehydrator. You can then enjoy the dried fruit as a snack, add it to a cake, or drop it in some muesli. To freeze sloes, wash and dry the fruit and then put them in freezer bags. In the freezer, the fruit will keep for several months.

Using sloes: What you can do with the fruit

Sloes are extremely versatile and have been used in a wide range of recipes for centuries. A classic sloe recipe is, of course, sloe gin. However, sloe jam or juice are also delicious and healthy treats.

Sloe juice and syrup

Sloe juice is easy to make from sloes, water, sugar and lemon juice. The juice is packed with vitamin C and flavonoids as well as tannins and other bitter substances. Flavonoids are particularly healthy; they have a diuretic effect, stimulate the appetite, and help with bladder infections. Sloe syrup has similar properties and can be made by boiling down sloes with water, sugar and lemon juice.

Sloe wine, brandy and liqueur

If you are looking for something a little stronger, why not try sloe wine or gin. Sloe wine is made with water, sugar and fermenting yeast in a wine balloon. You can make it tangy, like a red wine, or sweet, like a dessert wine, depending on the fermentation process.

For pure sloe gin, you will need to know how to make gin. However, you can instead opt for a sloe gin liqueur, which is much easier to make, and is known as sloe gin. To make the sloe liqueur, mix sloes with sugar and gin, rum, vodka or schnapps. If you like, spice it up with cinnamon, cloves or star anise.

Sloe jam

Sloe jam is a delicious way to preserve the berries. The recipe for making sloe berry jam is simple: boil down your sloes with preserving sugar in a ratio of one to one.

Read our article on growing sloes to learn all about cultivating blackthorn in your own garden.