Sloe berries and blackthorn blossoms are loved by gardeners, bees and birds alike. Read on to find out what to consider when planting, caring for and propagating blackthorn.
Blackthorn (Prunus spinosa) has long been a part of our landscape as a native wild shrub. However, it also makes a beautiful addition to gardens as a flowering hedge or feature tree. Blackthorn produces delicious, healthy fruit in autumn, and is a safe habitat and food source for many insects, birds and butterflies. Here is our in-depth guide on the origin and varieties of blackthorn, and how to plant, care and propagate the shrub at home.
- Sloe: origin and properties
- Blackthorn varieties
- Planting sloes: when, where and how
- Propagating blackthorn
- Blackthorn care
- Are sloes bee and bird friendly?
Sloe: origin and properties
Prunus spinosa is more commonly known as blackthorn or sloe. Sloes belong to the genus Prunus and are members of the rose family (Rosaceae). Blackthorn is native throughout Europe and the Middle East, and has even found its way to the Caucasus mountains and North Africa. The shrub can be found at altitudes of up to 1500 metres and is present in almost all continents. In the wild, it is often found along roadsides, in vineyards, along forest edges, wild hedges or hillsides.
The deciduous blackthorn grows as a shrub or bushy tree with several trunks. It can grow to a height of three to five metres when fully grown and has very dark, almost black bark that cracks with age. Blackthorn shoots are covered with lots of prickly thorns, and its leaves are three to four centimetres long, elliptical in shape and matt dark green. In autumn, these leaves turn yellow and slightly red.
Sloe blossom: when does blackthorn flower?
Blackthorn is one of the first shrubs to flower in spring. Its lush white blossoms are not only beautiful, but provide valuable nutrition to bees and insects. From the end of March to April, blackthorn produces many small, snow-white flowers.
Tip: How can you tell blackthorn and hawthorn apart? Blackthorn blossoms before its leaves appear. Hawthorn flowers, meanwhile, only appear after the shrub has foliage. Therefore, if you see a bare shrub with white flowers, you know it is a sloe!
Sloe berries: how to identify the fruits of the blackthorn
Sloe berries appear in late autumn and look like very small, round plums. They are black-purple to black-blue, and, when wild, grow up to one centimetre wide. Cultivated sloe berries grow even larger, with a diameter of up to two centimetres.
Nowadays, you can get hold of both wild and cultivated blackthorn, the latter of which promises a higher yield.
Sloe varieties for growing in the garden:
- ‘Godenhaus’: High yield and strong, healthy growth
- ‘Merzig’: Large fruits, well suited for sloe gin and liqueurs
- ‘Nittel’: Large fruits, slow growth, low pruning requirement
- ‘Purpurea’: In contrast to other varieties, it has purple-red foliage
- ‘Reto’: New variety, forms large fruits, less acidic
- ‘Rosea’: Flowers not white but pink, also has red foliage
- ‘Trier’: Fruit size and vigour are most similar to the wild blackthorn
Planting sloes: when, where and how
When to plant sloes?
- Potted plants: In spring and autumn
- Bare-root shrubs: In autumn
Where to plant sloes?
- Sunny, warm location
- Nutrient-rich, well-drained soil
- Prefers dry soil, avoid waterlogging at all costs
- Ideal pH value: 6-8.5
Tip: Blackthorn looks particularly good in a mixed hedge with other native wild shrubs, such as rosehip (Rosa canina) or juniper (Juniperus).
How to go about planting sloes
- Loosen the soil well
- Enrich with compost or Plantura All Purpose Plant Food
- Adjust the pH value by adding lime or fertilising with eggshells or wood ash
- Dig a planting hole that is at least twice as wide and deep as the root ball
- Freshly cut the main roots of the plant, cut off damaged or rotten root shoots.
- Planting distance for single plant: 3 metres
- Planting distance for hedge plant: 2 metres
- Fill in the planting hole
- Water well
Tip: People often complain about the vigorous, spreading root system of sloes. However, these broad roots are ideal for strengthening garden slopes.
There are a few ways to propagate blackthorn.
Four methods for propagating blackthorn:
- Wood cuttings
- Root runners
To propagate blackthorn with seeds, you will first need to collect them. Gather blackthorn berries in autumn and remove the seeds from the pulp. Store them in the fridge over winter, before sowing them in spring.
To propagate sloe from cuttings, cut a woody branch of about 20 centimetres from the shrub and remove any thorns and leaves. Put this cutting into potting soil, where it can take root, and then plant it out in spring.
Alternatively, you can propagate blackthorn with layering. First, select a long branch from your shrub and bend it to the soil. Attach it to the ground with a stone or a piece of wire. After a few weeks, this branch will have grown its own roots and can be cut from the mother shrub and planted elsewhere.
To propagate sloe using root runners, cut off a piece of root about 50 centimetres long with a sharp spade. Bury it in a new location to the same depth as it was when you collected it.
Blackthorn is undemanding and low maintenance. The only thing worth mentioning here is the shrub’s root system, which can grow vigorously. If you want to control this growth, install a root barrier. To do this, place a some form of obstruction, like a concrete ring, about 50 centimetres deep in the ground around your shrub. Alternatively, cut or pull out root runners every so often.
Watering and fertilising blackthorn
Blackthorn does not need a huge amount of water, so there is no need to water the plant, even during long dry spells. However, do ensure that your soil has the correct pH by applying some lime in spring. Alternatively, use wood ash or eggshells to fertilise the soil. If the soil is particularly low in lime, it is a good idea to repeat this process again in autumn.
A single application of fertiliser in spring is plenty for blackthorn. Use natural fertilisers like compost, or a long-acting plant food, like our Plantura All Purpose Plant Food. This fertiliser provides blackthorn with all the nutrients it needs for healthy growth, and releases these nutrients slowly and gently.
Sloe care summary:
- Watering is not necessary
- Apply lime in spring and autumn or fertilise with eggshells or wood ash
- Fertilise once in spring with compost or Plantura All Purpose Plant Food
Pruning sloe trees and hedges
Blackthorn is very tolerant to pruning, so feel free to cut back the plant as required. Whether you need to prune the shrub depends on what you want to use the shrub for. For the highest possible berry yield, prune and thin out your blackthorn every three years. This way, it will produce particularly large fruits. The best time to prune blackthorn is in spring, after flowering.
However, if you are less interested in an abundant harvest, and instead, want to create a habitat for bees, birds and butterflies, then avoid pruning your blackthorn shrub altogether.
Are sloes bee and bird friendly?
Absolutely! Few other shrubs have as high an ecological value as blackthorn. Countless mammals, birds and insects find shelter and food in blackthorn trees and hedges. Many butterflies, such as the peacock and brimstone butterflies, use blackthorn to lay their eggs. Caterpillars, too, find plenty of food in the undergrowth, as do many bird species, such as tits or warblers, who feed on the sloe berries. And special shrub-nesting birds, such as the red-backed shrike, like to build their nests in the blackthorn hedges or shrubs, finding both food and shelter there.
Who finds a home in the blackthorn bush?
- Around 18 species of wild bees and honey bees
- 70 butterfly species
- 20 bird species
- 173 insect species
- 18 species of mammals
Sloes are not just a tasty treat for the birds; there are plenty of ways you can enjoy the blackthorn berries too. Read our article on how to harvest and use sloes to find out more!