Garden Care Guide

Blackthorn Care

Prunus spinosa

A deciduous shrub with nearly black branches, very thorny, that spreads by suckers. It is known for its pure white flowers that open before the leaves in spring and its tart fruits (sloes) picked after the first frost. It is used to form impenetrable natural hedges and is very valuable for wildlife.

Hardy · -25 °C / -13 °F

Monthly care calendar

Timings are for a temperate Northern Hemisphere climate. In warmer areas tasks start earlier, in colder areas later; in the Southern Hemisphere shift them by six months.

January
  • Pruning: Main pruning time. Hard pruning can be carried out to shape hedges, rejuvenate the plant or control its spread.
  • General care: To control its spread, pull out the basal suckers coming from the roots.
February
  • Pruning: Finish pruning by the end of the month.
  • General care: Continue removing basal shoots.
  • Frost risk: As the flower buds swell, their sensitivity to frost increases.
March
  • Watering: Not needed. Spring rains are sufficient.
  • Fertilizing: Apply a balanced fertilizer or well-rotted organic fertilizer once when it wakes from dormancy.
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: It opens white flowers on black branches.
  • Pests & diseases: During humid and cool periods, monitor the leaves and trunk for signs of mold, spots and rot.
  • Frost risk: Flowers are very sensitive to frost.
April
  • Watering: If there is no rainfall, water every 15 days.
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: The leaves emerge.
  • Pests & diseases: Look for aphids (green or black clusters of small insects) on fresh shoot tips. If there are only a few, you can knock them off with a strong jet of water.
May
  • Watering: If there is no rainfall, water once a week.
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: Spread a 5-7 cm layer of mulch over the root zone; it retains soil moisture and suppresses weeds. Do not pile mulch against the trunk.
  • Pests & diseases: Look for aphids (green or black clusters of small insects) on fresh shoot tips. If there are only a few, you can knock them off with a strong jet of water.
June
  • Watering: Water deeply twice a week; prefer infrequent and generous watering over small and frequent. Water around the roots to a depth of 15-20 cm.
  • Pruning: Do shaping and hedge pruning.
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: Growth slows.
  • Pests & diseases: Look for aphids (green or black clusters of small insects) on fresh shoot tips. If there are only a few, you can knock them off with a strong jet of water.
July
  • Watering: Water deeply twice a week; prefer infrequent and generous watering over small and frequent. Water around the roots to a depth of 15-20 cm.
  • General care: The fruits continue to grow.
August
  • Watering: Water deeply twice a week; prefer infrequent and generous watering over small and frequent. Water around the roots to a depth of 15-20 cm.
September
  • Watering: If there is no rainfall, water once a week.
  • Fertilizing: It must absolutely not be given.
  • Pruning: Do the last formative pruning of the season; do not let it put out new shoots before frost.
  • Plant protection: Not needed; it is very hardy.
  • General care: The fruits (sloes) turn bluish-black but are still too astringent for harvest. Wait for the first frosts to harvest.
October
  • Watering: If there is no rainfall, water every 15 days.
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: After the first frosts, the astringency of the fruits decreases and they become harvestable. The leaves begin to drop.
  • Pests & diseases: During humid and cool periods, monitor the leaves and trunk for signs of mold, spots and rot.
  • Frost risk: The first frosts are beneficial for ripening of the fruit.
November
  • Plant protection: If symptoms spread and treatment is needed, consult a licensed plant-protection supplier or an agronomist. Plant protection products are regulated; follow local rules.
  • General care: Collect fallen leaves; many disease agents and pests overwinter under leaves.
  • Pests & diseases: During humid and cool periods, monitor the leaves and trunk for signs of mold, spots and rot.
December
  • Pruning: Once the tree is fully dormant, major pruning can begin toward the end of the month.
  • General care: Full dormancy period.

The care advice on this page is general and for information only; it is not professional advice. Plant age, soil and your garden’s microclimate can change the outcome. Plant protection products are mentioned only as general information; they are regulated, and the choice, dose and timing must be decided by a qualified professional under local rules. Consult a landscape architect or agronomist before applying.

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