Garden Care Guide

Gray Alder Care

Alnus incana

WARNING: This tree is native to cool, humid climates; it is NOT suitable for Izmir's hot, dry summers and its survival is very difficult. It fixes nitrogen with its roots and likes stream banks. Planting it is not recommended; Alnus cordata (Italian Alder) is a more suitable alternative.

Hardy · -30 °C / -22 °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
  • Watering: Not required; winter precipitation is sufficient.
  • Fertilizing: Not required, it produces its own nitrogen.
  • Pruning: The best time for structural pruning and clearing dead branches.
  • Plant protection: Dormant oil application if needed, for insects overwintering in dormancy.
  • General care: Start retaining soil moisture by spreading a thick layer of mulch over the root zone.
  • Pests & diseases: Check drainage against the risk of root rot.
  • Frost risk: None; it is frost tolerant.
February
  • Watering: Not required; winter precipitation is sufficient.
  • Pruning: While dormant, remove dry, broken, crossing and inward-growing branches so that air and light reach the inside of the crown.
  • Plant protection: Apply dormant oil if needed.
  • General care: Disinfect your pruning tools. Protect the mulch layer.
  • Pests & diseases: Check the trunk and branches for signs of fungus.
  • Frost risk: None; it is frost tolerant.
March
  • Watering: Start keeping the soil constantly moist (20-25 L/week); reduce if it rains.
  • Pruning: Not necessary; only remove root suckers.
  • Plant protection: Check the new leaves for aphids or alder leaf beetles (neem oil).
  • General care: Check the mulch layer and renew it if necessary.
  • Pests & diseases: Monitor for leaf spot diseases.
April
  • Watering: If there is no rainfall, water 1-2 times a week.
  • Pruning: Not necessary.
  • Plant protection: Watch out for the alder leaf beetle and its larvae (pyrethrin if necessary).
  • General care: Remove the weeds in the root zone.
  • Pests & diseases: Take special care that it does not go into water stress.
May
  • Watering: Water 2-3 times a week. The root zone should be wetted to a depth of 30-40 cm.
  • Pruning: Not necessary.
  • Plant protection: Continue checking for the alder leaf beetle.
  • 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: Yellowing of the leaves can point to overwatering or a drainage problem.
June
  • Watering: Water deeply 3-4 times a week, early in the morning. The root zone should be wetted to a depth of 30-40 cm. Frequent shallow watering pulls the roots to the surface.
  • Pruning: Never, only remove broken branches.
  • Plant protection: Check constantly for spider mites (abamectin).
  • General care: Add extra mulch to keep the root zone shaded.
  • Pests & diseases: Watch for signs of severe stress such as leaf scorch and sudden wilting.
July
  • Watering: Water deeply 3-4 times a week, early in the morning. The root zone should be wetted to a depth of 30-40 cm. Frequent shallow watering pulls the roots to the surface.
  • Pruning: Never, only remove broken branches.
  • Plant protection: Watch out for spider mites and other stress-related pests.
  • General care: Watering is the most important care task.
  • Pests & diseases: The risk of death from Phytophthora root rot (sudden wilting) and heat stress is high.
August
  • Watering: Water deeply 3-4 times a week, early in the morning. The root zone should be wetted to a depth of 30-40 cm. Frequent shallow watering pulls the roots to the surface.
  • Pruning: Never, only remove broken branches.
  • Plant protection: Continue checking for spider mites.
  • General care: In this climate, watering is vital to keep this tree alive.
  • Pests & diseases: Monitor a tree under severe stress for any signs of disease (e.g., trunk oozing).
September
  • Watering: Water 2-3 times a week. The root zone should be wetted to a depth of 30-40 cm.
  • Pruning: Not necessary. Only remove branches that dry out during summer.
  • Plant protection: Watch a tree under stress for pests.
  • General care: Maintain the mulch in the root zone. Keep in mind that it is hard to keep this tree alive in this climate.
  • Pests & diseases: Check for branch dieback caused by summer stress and for the risk of fungal diseases.
October
  • Watering: If there is no rainfall, water 1-2 times a week.
  • Pruning: Not needed. Wait for winter to prune.
  • General care: The most suitable time for planting new seedlings (if it is to be tried). You can use the fallen leaves as mulch.
  • Pests & diseases: Make sure the roots are healthy during planting.
November
  • Watering: Not required; autumn precipitation is beginning.
  • General care: Collect fallen leaves; many disease agents and pests overwinter under leaves.
  • Pests & diseases: Stake young seedlings against winter storms.
December
  • Pruning: Once the tree has gone fully dormant, you can begin pruning.
  • General care: Maintain the mulch in the root zone throughout winter.
  • Pests & diseases: Check the trunk for winter cracks that may have formed.

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.

Want reminders for every plant in your garden? Our garden-care app with monthly task lists and frost alerts is currently available in Turkish; the English version is on the way.

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