This fruit tree produces surprising fruits, sloes, that are always best when they’ve burst just after the first frost spells.
Blackthorn basic facts
Name – Prunus spinosa
Family – Rosaceae
Type – shrub
Height – 3 to 16 feet (1 to 5 m)
Exposure – full sun to part shade
Flowering – March to April
Foliage – deciduous
Planting blackthorn
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.
Pruning blackthorn
If you must prune or cut back your blackthorn, avoid proceeding after the blooming, or you won’t be harvesting any fruits.
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.
Harvesting sloes
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.
Keeping sloes
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.
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.
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!
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Blackthorn sloes shared by Marek Michalski under © CC BY-NC 2.0
Blackthorn blooming shared by Hornbeam Arts under © CC BY-NC 2.0
I’ve been picking sloes in the hedgerows for about 3 years and making sloe gin. It’s very popular. I’ve just a ‘grow it’ box , for growing sloes from seed. The instructions says to place the soil and seeds (after wetting) into a plastic bag. Keep the bag at a temperature of around 18-20C for about 2 weeks. After this, place the seeds in the fridge for at least 18 weeks. If these instructions are correct, in which month is it best to begin this process so that the seedlings can be planted outside in the most suitable month?
Hello Chris! Sowing blackthorn is a long process indeed. I’m supposing the seeds have already come from dry storage, they’re in a deep dormant phase.
The best planting window being fall, say mid-September, it would make sense to start early-to-mid-May which is 20 weeks earlier.
However, it isn’t advised to plant young seedlings directly into the ground on the first winter. It’s best to wait for them to be around a year old or so before planting them to the ground. So you could start them now (since you’ve got the box) and keep them in a lean-in or unheated greenhouse over the winter before planting them in fall next year. That would be best since they would have grown a bit and would be around 8 months old upon planting to the ground.
If you’ve got spare seeds, try sowing some now directly where you plan to grow them. They’ll have their cold cycle during winter and naturally sprout in spring.
If you have lot of seeds and can accept heavy dieback (like 3/4ths dying off), you can go ahead and start the process next May and plant the seedlings to the ground directly as they sprout. Having those seedlings face the harsh winter immediately will give them “staying power” and train them to face the cold… for those that survive, of course!
I had a beautiful blackthorn hedgerow which grew for over 10yrs. However it succumbed to black knot fungus which I was completely unaware of at the time! No one told me to watch out for this and it was too late for treatment when I finally discovered what was wrong!! So upset!!
Hi Mags! Oh, my, I understand that you must really be upset! Black knot fungus is usually expected on fruit trees, and having a hedge suffer and die must have been a disappointment. Hopefully you found a new shrub to grow!
Blackthorn does well in my clay soil. The rhs entry on it corroborates this. Saying it despises clay is frankly wrong. It also tolerates fairly poor soils, half shade and is a really tough hedgerow plant.
Hi grrrrrl, thank you for your comment. The word “despise” is too strong, I’ll change it to reflect your experience. Thanks for sharing your added information about your blackthorn – always good to see someone who’s happy with this tough but fruit-bearing hedge plant!