Garden Care Guide

Italian Alder Care

Alnus cordata

A fast-growing tree that enriches the soil by fixing nitrogen from the air through the nodules on its roots. It can grow even in difficult and infertile soils and is used for roadside planting and as a windbreak.

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 and weak branches.
  • Plant protection: Dormant oil application if needed, for insects overwintering in dormancy.
  • General care: Choose seedlings and prepare the site for new plantings.
  • Pests & diseases: Check for root and trunk fungi (e.g. Armillaria).
  • 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 to prevent the spread of disease.
  • Pests & diseases: Against the risk of root rot, make sure drainage is good.
  • Frost risk: None; it is frost tolerant.
March
  • Watering: For young trees, water if necessary (15-20 L every 15 days). Reduce if it rains.
  • Pruning: Not necessary; only remove root and stem suckers.
  • Plant protection: Check the new leaves for aphids or alder leaf beetles (neem oil).
  • General care: Add mulch around the base of young trees to retain moisture.
  • 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: Be careful of the alder leaf beetle and its larvae (pyrethrin if necessary).
  • General care: Remove weeds from the root zone of young trees.
  • Pests & diseases: Watch for fungal diseases (leaf spot).
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: Remove only broken or hazardous branches.
  • Plant protection: Spider mites can be a problem in hot, dry weather (abamectin).
  • General care: Do not neglect watering, to prevent water stress.
  • Pests & diseases: Monitor for damage from the alder leaf beetle (Galerucella luteola).
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: Remove only broken or hazardous branches.
  • Plant protection: Continue checking for spider mites.
  • General care: In extreme temperatures, check whether the leaves of young trees are scorching.
  • Pests & diseases: Monitor for signs of Phytophthora root rot (sudden wilting).
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: Remove only broken or hazardous branches.
  • Plant protection: Continue checking for spider mites.
  • General care: Make sure the water penetrates deeply; avoid shallow watering.
  • Pests & diseases: Check the base of the tree for honey fungus (Armillaria).
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 broken branches.
  • Plant protection: Pest activity decreases; take action only if necessary.
  • General care: Prepare for planting new seedlings; it is one of the ideal times.
  • Pests & diseases: Check drainage against the risk of root rot (Phytophthora).
October
  • Watering: If there is no rainfall, water 1-2 times a week.
  • Pruning: Not needed. Wait for winter to prune.
  • General care: The best time for planting a new tree. You can use the fallen leaves as mulch.
  • Pests & diseases: Make sure the roots are healthy during planting.
November
  • General care: Collect fallen leaves; many disease agents and pests overwinter under leaves.
  • Pests & diseases: Stake young seedlings against the risk of toppling in winter storms.
December
  • Pruning: Once the tree has gone fully dormant, you can begin pruning.
  • General care: Keep the root zone clean.
  • 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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