This fruit tree produces surprising fruits, sloes, that are always best when they’ve burst just after the first frost spells.
Blackthorn basic facts
Type – shrub
Height – 3 to 16 feet (1 to 5 m)
Exposure – full sun to part shade
Flowering – March to April
Fruit – sloe, plural sloes
(a famous crossword trick)
Foliage – deciduous
It is ideal to plant blackthorn in fall to boost root development before winter.
You can still nonetheless plant your blackthorn in spring if you’ve purchased it in a container.
- Blackthorn loves sunbathed locations to produce sloes.
- It appreciates rather rich soil.
- Poor and clayish soil isn’t its best growing environment.
- Take care, if this is the case, to water regularly at the beginning for roots to penetrate well.
Take note that blackthorn is… full of thorns, place it well so that you won’t be pricked too often when passing by!
It is thus also ideal to create a tough defensive hedge, on top of its ornamental appeal.
Care and pruning of blackthorn
Caring for blackthorn is very easy because it is a shrub that requires quasi no care once it has settled in correctly.
- Regularly water over the 1st year after planting.
- Fertilize poor soil with shrub fertilizer during the 2 or 3 first years.
If your blackthorn turns invasive:
- Wait for fall to cut it back drastically every 2 or 3 years.
- Remove suckers sprouting from the base often during the year.
Blackthorn can cope well with severe pruning, hatracking and even being cut down to the stump.
Caution: blackthorn spikes can be over 4 inches (10 cm) long, are very sharp and very strong.
- When pruning, it’s important to wear thick gloves and especially protective glasses to protect your eyes.
- You can also snip off spikes on lower branches with pruning shears. This makes weeding underneath them easier for the season!
It is very easy to harvest sloes from the blackthorn but, be careful, these fruits only really have any value if harvested at exactly the right time.
Sloe is astringent and bitter and doesn’t have much culinary value if harvested too early.
- Wait for a couple fall frost spells to occur before collecting the sloes.
- The sloe must be mush, with wilted skin: this is when it is at its best.
- Harvest sloes together with medlar. Both are best when over-ripe. This is called bletting.
Sloes will keep for a short while if dried out in the sun, but best is to freeze them and thaw right before cooking.
Learn more about blackthorn
Blackthorn, also called sloe bush, is part of the large Prunus family, like the apricot tree, plum tree, almond tree, peach tree and cherry tree. It actually can be used as a graft-holder for apricot trees, plum trees and peach trees.
Birds love building nests in the tree. The sharp thorns protect eggs and hatchlings from predators such as cats.
Often used to create defensive hedges, its bountiful fruits are sometimes forgotten, which is a shame because they are delicious after they’ve frozen through.
Its early blooming is simply beautiful, covering the tree even before leaves have appeared. This gives the tree a serene, meditative bearing, much like that of a Japanese garden.
Sloes are astringent if harvested too early, but always have high vitamin C contents as well as organic acids and tannin compounds.
Sloes enter into the preparation of very many recipes for spirits, wines and jams.
Smart tip about blackthorn
During the beautiful spring blooming, you can snip a couple branches off from your blackthorn and arrange them in a large vase, the decorative impact will impress all!
Blackthorn on social media
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Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Blackthorn sloes (also on social media) by Marek Michalski under © CC BY-NC 2.0
Serious spikes by Valary Dymond ★, Nature & Garden contributor
Blooming blackthorn by Hornbeam Arts under © CC BY-NC 2.0