Garden Care Guide

Onion Care

Allium cepa

A bulb vegetable grown from sets or seed and eaten fresh or dried. It needs dry soil as harvest approaches; too much water rots the bulb.

Hardy · -10 °C / 14 °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: In the cool season, rainfall is often enough; during a long dry spell, water every 10-15 days just enough to keep the soil moist.
February
  • Watering: In the cool season, rainfall is often enough; during a long dry spell, water every 10-15 days just enough to keep the soil moist.
  • General care: Spring planting is also possible; plant the sets as soon as the soil can be worked.
March
  • Watering: In the cool season, rainfall is often enough; during a long dry spell, water every 10-15 days just enough to keep the soil moist.
  • Fertilizing: Apply nitrogen fertilizer once when growth starts; do not apply nitrogen after May, or the onions will not form bulbs and will not store well.
  • General care: Spring planting is also possible; plant the sets as soon as the soil can be worked.
  • General care: Clear weeds regularly; because onion leaves are narrow, onions cannot compete with weeds.
April
  • Watering: If there is no rain, water every 7-10 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: Clear weeds regularly; because onion leaves are narrow, onions cannot compete with weeds.
  • General care: Harvest (spring onions): Pull them as needed once the green leaves are 20-30 cm tall.
  • Pests & diseases: After humid, cool nights, look for yellowish or brown, oily-looking spots on the leaves and mold on the undersides (downy mildew; on tomato and potato, late blight); remove diseased leaves immediately and do not water in a way that wets the leaves.
  • Pests & diseases: If onions turn yellow and wilt and maggots are seen inside the bulb (onion fly), uproot and remove the diseased plants.
  • Pests & diseases: Check the flowers and leaves for silvery scratch marks (thrips).
May
  • Watering: If there is no rain, water every 7-10 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: Clear weeds regularly; because onion leaves are narrow, onions cannot compete with weeds.
  • General care: Harvest (spring onions): Pull them as needed once the green leaves are 20-30 cm tall.
  • Pests & diseases: After humid, cool nights, look for yellowish or brown, oily-looking spots on the leaves and mold on the undersides (downy mildew; on tomato and potato, late blight); remove diseased leaves immediately and do not water in a way that wets the leaves.
  • Pests & diseases: If onions turn yellow and wilt and maggots are seen inside the bulb (onion fly), uproot and remove the diseased plants.
  • Pests & diseases: Check the flowers and leaves for silvery scratch marks (thrips).
June
  • Watering: Stop watering completely once the leaf tips begin to turn yellow.
  • 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: Harvest (dry onions): Pull them when more than half of the leaves have fallen over and turned yellow; dry them for 1-2 weeks in a shaded, airy place, then cut off the leaves.
  • Pests & diseases: Check the flowers and leaves for silvery scratch marks (thrips).
July
  • Watering: Deep watering 1-2 times a week is enough; frequent, shallow watering draws the roots to the surface.
  • General care: Harvest (dry onions): Pull them when more than half of the leaves have fallen over and turned yellow; dry them for 1-2 weeks in a shaded, airy place, then cut off the leaves.
October
  • Watering: If there is no rain, water every 7-10 days.
  • General care: Plant onion sets with the tips just above the soil surface, 25 cm between rows and 10 cm within the row. For spring onions they can be planted closer together.
November
  • Watering: In the cool season, rainfall is often enough; during a long dry spell, water every 10-15 days just enough to keep the soil moist.
  • General care: Plant onion sets with the tips just above the soil surface, 25 cm between rows and 10 cm within the row. For spring onions they can be planted closer together.
December
  • Watering: In the cool season, rainfall is often enough; during a long dry spell, water every 10-15 days just enough to keep the soil moist.

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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