Plant Profile
AlliumAllium
Leek (Allium) is a versatile and robust plant, valued in many cuisines worldwide. With its mild, oniony flavor and health benefits, it is an asset to any garden and diet. From sowing to harvest, leeks are relatively easy to care for and forgive minor mistakes.
Quick profile
Key data
Suitable growing locations:
Good neighbors
CarrotCeleryStrawberryChamomile
Avoid
BeanPeaCabbage
Indoor & direct sowing
Allium: Sowing and germination
Leeks are usually sown directly into the open ground.
Sow outdoors from March to August. An early sowing in March/April allows for an earlier harvest.
Planting & site
Allium: Planting and spacing
Plant out pre-grown young plants into the open ground. Ensure adequate spacing.
Site & practical notes
Temperature & frost
Allium: Temperature and site
Water & nutrients
Allium: Water, nutrients and care
Container & growth
Allium: Container, support and growth
Year plan
Allium Calendar
Winter-hardy varieties allow for harvest well into spring.
Recurring tasks
Relevant now
June
- Sow leeks (open ground)Soil is workable: Very late sowing for a late harvest.
- Hill up for blanchingPlants are growing well: Earth up around the stems to lengthen the white shaft.
Next up
July
- Harvest summer leeksPlants are mature: Start harvesting early summer leek varieties.
- FertilizePlants are growing: Liquid fertilizer or compost tea to promote growth.
Monthly tasks
Single tasks from monthly data; repeated seasonal windows are shown in the overview above.
January
Planting
- Frost protection for overwintering plantsSevere frost expected: Cover with brushwood or fleece.
February
Growing
- Loosen soilSoil is workable: If not already done, prepare the soil for the upcoming season.
March
Direct sowing
- Prepare soil for sowingSoil is workable: Loosen soil deeply, incorporate compost.
- Sow leeks (open ground)Soil temperature suitable: Early varieties for an earlier harvest.
Harvest
- Harvest winter leeksPlants are mature: Last harvest of late winter leek varieties.
April
Direct sowing
- Sow leeks (open ground)Soil is workable: Continue sowing for summer and autumn harvest.
Planting
- Plant out young plantsPlants have 4-5 true leaves: Plant pre-grown plants into the open ground, pay attention to spacing.
Growing
- WeedWeeds are visible: Keep young plants and sowings free of weeds.
May
Direct sowing
- Sow leeks (open ground)Soil is workable: Late sowing for a late harvest.
Growing
- Loosen soil and waterDry weather: Hoe regularly and water well during dry periods.
June
Direct sowing
- Sow leeks (open ground)Soil is workable: Very late sowing for a late harvest.
Growing
- Hill up for blanchingPlants are growing well: Earth up around the stems to lengthen the white shaft.
August
Direct sowing
- Sow leeks (late varieties)Soil is workable: Sow varieties intended for autumn and winter harvest.
Harvest
- Harvest summer leeksPlants are mature: Main harvest time for summer leek varieties.
September
Harvest
- Harvest leeksPlants are mature: Harvest summer and early autumn leek varieties.
October
Harvest
- Harvest autumn leeksPlants are mature: Main harvest time for autumn leek varieties.
Growing
- Prepare leeks for storageHarvested leeks: Store leeks cool and dark, e.g., in sand or damp sawdust.
November
Harvest
- Harvest leeksPlants are mature: Harvest autumn and early winter varieties.
December
Planting
- Frost protection for overwintering plantsSevere frost expected: Cover with brushwood or fleece.
Harvest
- Harvest winter leeksPlants are mature: Harvest winter leek varieties, depending on the weather.
Flowering & pollination
Allium Flowering & pollination
Flowering period
June - August (in the second year)
Flower type
Umbellate flower clusters
Flower color
White to pink-purple
Self-fertility
self-fertile
Pollinator needed
yes
Overview
Insect pollination
Notes
Leeks flower in the second year after sowing. The flowers are attractive to bees and other insects.
Companion guide
Allium Companion guide
Good neighbors
CarrotCeleryStrawberryChamomileMarigoldtomato
Avoid
BeanPeaCabbage
Use & storage
Allium Use & storage
Harvesting can take place from summer until the following spring, depending on the variety and sowing time. Winter-hardy varieties can remain in the bed over winter.
Storage
Cool and moist
Storage life
In the ground: several months; in sand/sawdust: 2-3 months; in refrigerator: 1-2 weeks; frozen: up to 12 months
Flavor
Mild oniony, slightly sweet, earthy
Harvest
Harvesting can take place from summer until the following spring, depending on the variety and sowing time. Winter-hardy varieties can remain in the bed over winter.
Culinary uses
Processing
After harvest
Remove soil from harvested leeks, trim outer, damaged, or very green leaves. Shorten roots. Wash thoroughly, especially between leaf layers, to remove soil.
Notes
Leek is a versatile vegetable that can be used raw or cooked. It makes an excellent base for soups, stews, and sauces.
Edibility & safety
Allium Edibility & safety
For people
In brief: which parts are edible, which parts remain risky, and whether raw consumption makes sense.
Safety notes
Leek is non-toxic to humans and has been used as food for centuries. Like other Allium species, it can be toxic to pets (especially dogs and cats) in large quantities.
Animal safety
For animals, the specific plant part matters here: some parts may be suitable, while others should be avoided. At least one critical rating is listed for 12 animal types.
Each row shows which parts are more suitable and which parts are critical.
Companion animals
DogNo suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
No suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
Amount, Frequency of feeding, Individual sensitivity
Vomiting, Diarrhea, Abdominal pain
contact a vet if ingested
All parts of the leek contain disulfides and thiosulfates, which can cause oxidative stress and hemolysis in dogs. Even small amounts can cause symptoms in sensitive animals. No parts are considered safe for canine consumption. If ingestion is suspected, contact a veterinarian. For severe symptoms such as difficulty breathing or collapse, seek emergency veterinary care.
Open animal page
CatNo suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
No suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
Large quantities, Repeated ingestion
Vomiting, Diarrhea, Lethargy
contact a vet if symptoms appear
All parts of the leek contain disulfides and thiosulfates that can cause oxidative damage to red blood cells in cats, potentially leading to hemolytic anemia. Even small amounts may trigger symptoms in sensitive animals. No parts are considered safe for regular consumption. Seek veterinary advice immediately if ingestion is suspected.
Open animal page
RabbitNo suitable parts listed
No risk parts listed
No suitable parts listed
No risk parts listed
unknown
Leek contains Allium-typical disulfides that can cause hemolytic anemia in rabbits. While rabbits are less sensitive than dogs or cats, there is a risk with ingestion of significant amounts. All plant parts should be avoided. Contact a veterinarian if ingestion is suspected.
Open animal page
Guinea pigShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Frequent feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
contact a vet if symptoms appear
The edible parts of leek (shaft, tender leaves, flowers) can be offered in small amounts as a treat for guinea pigs, but contain compounds that may cause gastrointestinal upset if overfed. Roots, tough outer leaves, and woody flower stalks should be avoided. Consult a veterinarian if signs of discomfort appear.
Open animal page
HamsterShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Frequent feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
contact a vet if symptoms appear
No direct species-specific source was found for hamsters. This is a cautious inference from the guinea pigs profile and the known plant-part risks.
Open animal page
BudgieNo suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
No suitable parts listed
Shaft (white and light green), Leaves (tender, green parts), Flowers (as edible garnish)
All aerial parts contain sulfur-containing compounds, Small body size increases sensitivity, Cumulative effect with repeated intake
Vomiting, Diarrhea, Gastrointestinal irritation
contact a vet if symptoms appear
Budgies are small and sensitive to Allium compounds. While leek is edible for humans, even small amounts can cause gastrointestinal irritation in birds. No species-specific studies exist, but conservative classification based on toxicity in related bird species and known mechanisms of action.
Open animal pageFarm animals
HorseNo suitable parts listed
No risk parts listed
No suitable parts listed
No risk parts listed
unknown
Leek is edible for horses in small amounts, but larger quantities can be toxic due to disulfides and thiosulfates. Edible parts are the shaft, tender leaves, and flowers; roots, tough outer leaves, and woody flower stalks should be avoided. Consult a veterinarian if symptoms occur.
Open animal page
ChickenShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Repeated feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
observe
Leek is edible for humans but contains Allium-typical compounds that can cause gastrointestinal irritation in chickens when consumed in large quantities. Edible parts are suitable as occasional treats in small amounts, while roots, tough outer leaves, and woody stalks should be avoided. No specific chicken studies available, but conservative classification based on known Allium toxicity in birds and mammals.
Open animal page
DuckShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Repeated feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
contact a vet if symptoms appear
No direct species-specific source was found for ducks. This is a cautious inference from the geese profile and the known plant-part risks.
Open animal page
GooseShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Repeated feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
contact a vet if symptoms appear
The edible shaft and tender leaves of leek can be given to geese in small amounts as an occasional treat, but repeated ingestion or large quantities pose a risk of hemolytic anemia due to contained thiosulfates. Roots and tough outer parts should be avoided.
Open animal page
SheepShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Root consumption, Consumption of tough outer leaves
Gastrointestinal upset, Diarrhea, Bloating
observe
Leek is edible for sheep in small amounts, but certain parts like roots and tough outer leaves can cause gastrointestinal upset. Like other Allium species, it contains compounds that can be toxic in high doses. Feed only the tender, edible parts and limit quantity. Consult a veterinarian if signs of poisoning appear.
Open animal page
GoatShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Repeated feeding, Sensitive animals
Gastrointestinal upset, Diarrhea, Anemia with repeated ingestion
contact a vet if symptoms appear
Tender parts of leek are edible for goats in small amounts, but roots, tough outer leaves, and woody stalks contain Allium compounds that can cause hemolytic effects with repeated ingestion. Suitable as occasional forage, but not as primary feed.
Open animal page
CattleNo suitable parts listed
Leaves, Shaft, Flowers
No suitable parts listed
Leaves, Shaft, Flowers
Large quantities, Ruminants more sensitive to Allium toxicity
Gastrointestinal irritation, Vomiting, Diarrhea
contact a vet if symptoms appear
Leek contains disulfides and thiosulfates that can cause oxidative damage to red blood cells in ruminants like cattle, particularly in larger quantities. While cattle are less sensitive than horses or small ruminants, there is a risk with substantial consumption. Edible parts for humans are not necessarily safe for cattle due to the compounds present.
Open animal page
PigShaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Shaft (white and light green), Leaves (tender, green parts)
Roots, Very tough, outer leaves, Woody flower stalk after bolting
Large quantities, Repeated feeding, Sensitive individuals
Gastrointestinal upset, Vomiting, Diarrhea
contact a vet if symptoms appear
Leek is suitable for pigs in normal amounts as part of a balanced diet, but certain parts like roots and tough outer leaves should be avoided. Like other Allium species, excessive consumption can lead to gastrointestinal upset. The edible parts (shaft, tender leaves, flowers) can occasionally be fed as treats. If signs of poisoning appear, a veterinarian should be consulted.
Open animal pageThese guidelines are for general information only and do not replace veterinary diagnosis. If critical plant parts were ingested or the animal shows unusual behaviour or symptoms, seek veterinary advice.
Max risk
unknown
Highest status
do not feed
Urgency
contact a vet if ingested
Saving seed
Allium Saving seed
Seed saving
yes
Seed viability
2 - 3 years
Practical tips
Allium Practical tips
Common beginner mistakes
Success pattern
High-impact tips
Plant Profile
Additional plant images
Health
Pests, Diseases
Pests
Leek Moth
Leek moth larvae tunnel into the leaves and stems of leeks, which can lead to significant crop loss. There are multiple generations per year.
Onion Fly
Onion fly larvae feed on the roots and base of leeks, which can lead to plant death. Young plants are particularly vulnerable.
Leek Miner
Leek miner larvae cause characteristic mines in the leaves. Infestation can weaken plants and make them more susceptible to diseases.
Diseases
Leek Rust
Leek rust is a fungal disease that spreads rapidly in humid weather. It weakens plants and can reduce yield.
Downy Mildew
Downy mildew is a fungal disease that occurs in cool, humid weather. It can affect entire crops and significantly reduce yield.
White Rot
White rot is a severe fungal disease that attacks leeks from the base, leading to plant death. The fungus can survive in the soil for many years.
Deficiencies
Nitrogen Deficiency
- Leaves turn pale green to yellowish, starting on older leaves
- Stunted growth
- Thin stems
Potassium Deficiency
- Leaf margins yellow and die back (necrosis)
- Weak, soft stems
- Reduced frost hardiness
Phosphorus Deficiency
- Leaves turn purplish or dark green
- Poor root growth
- Delayed development
Plant health
Diagnosis help
Allium Diagnosis help
Pest groups
Insects (Leek Moth, Onion Fly, Leek Miner, Thrips)
Disease groups
Fungal diseases (Leek Rust, Downy Mildew, White Rot)
Prevention
Diagnosis
Pay attention to early signs of pests or diseases. Regular inspection of leaves (top and bottom) and the stem base is crucial. Consider weather conditions and the planting history of the bed.
Cultural prevention
Monitoring
First response
Diagnostic rules
Tunnels in leaves and stems
Possible causes: Lauchmotte, Lauchminierfliege
- Check for larvae or pupae inside tunnels.
- Note the type of tunnels (straight vs. zigzag).
Wilting and yellowing of leaves, rotting base
Possible causes: Onion fly, White rot, Nitrogen deficiency
- Check plant base for larvae or white fungal growth.
- Check soil moisture and fertilization.
Orange-brown pustules on leaves
Possible causes: Lauchrost
- Check humidity and air circulation.
- Verify plant spacing.
Yellowish spots on leaves, greyish-purple mold
Possible causes: Downy mildew
- Check weather conditions (cool, humid).
- Examine the underside of leaves closely.
FAQ
When is the best time to sow leeks?
Leeks can be sown directly into the open ground from March to August. For an earlier harvest, pre-cultivation indoors or in a greenhouse from February is recommended.
How often do leeks need watering?
Leeks require consistent watering, especially during the growth phase. During dry periods, water regularly and thoroughly, preferably at the base of the plant.
What can be done against leek pests like the leek moth?
To protect against leek moths and other pests, fine-mesh insect netting is the most effective method. Crop rotation and promoting beneficial insects also help.
Can leeks be harvested in winter?
Yes, many leek varieties are winter-hardy and can be harvested throughout the winter as long as the soil is not frozen. Light protection with brushwood can be beneficial during severe frost.
Why is my leek bolting?
Premature bolting (flower stalk formation) is often caused by temperature fluctuations, drought stress, or choosing non-bolt-resistant varieties. Ensure consistent care and select suitable varieties.
Is Allium safe for Dog?
Allium is classified as do not feed for Dog. Risk: unknown. Urgency: contact a vet if ingested. All parts of the leek contain disulfides and thiosulfates, which can cause oxidative stress and hemolysis in dogs. Even small amounts can cause symptoms in sensitive animals. No parts are considered safe for canine consumption. If ingestion is suspected, contact a veterinarian. For severe symptoms such as difficulty breathing or collapse, seek emergency veterinary care.
Is Allium safe for Cat?
Allium is classified as do not feed for Cat. Risk: unknown. Urgency: contact a vet if symptoms appear. All parts of the leek contain disulfides and thiosulfates that can cause oxidative damage to red blood cells in cats, potentially leading to hemolytic anemia. Even small amounts may trigger symptoms in sensitive animals. No parts are considered safe for regular consumption. Seek veterinary advice immediately if ingestion is suspected.
Is Allium safe for Rabbit?
Allium is classified as not established for Rabbit. Risk: unknown. Urgency: unknown. Leek contains Allium-typical disulfides that can cause hemolytic anemia in rabbits. While rabbits are less sensitive than dogs or cats, there is a risk with ingestion of significant amounts. All plant parts should be avoided. Contact a veterinarian if ingestion is suspected.
Is Allium safe for Guinea pig?
Allium is classified as do not feed for Guinea pig. Risk: unknown. Urgency: contact a vet if symptoms appear. The edible parts of leek (shaft, tender leaves, flowers) can be offered in small amounts as a treat for guinea pigs, but contain compounds that may cause gastrointestinal upset if overfed. Roots, tough outer leaves, and woody flower stalks should be avoided. Consult a veterinarian if signs of discomfort appear.
Guides
Related guides
Guide
Growing Autumn Vegetables for Winter Harvests
Learn how to grow autumn vegetables such as kale, spinach, lamb's lettuce, and leeks for harvests into winter.
Guide
Toxic Garden Plants for Cats: Safer Planning
Learn which garden plants can be risky for cats, how to plan safer beds, and what to do if a cat eats a toxic plant.
Guide
Chickens in the Garden: Safe Plants and Zones
Learn how to design a chicken-friendly garden with suitable plants, protected beds, and well-planned activity areas.
Guide
Dogs in the Garden: Windfall Fruit and Risks
Keep your garden dog-safe by managing windfall fruit, seeds, stored crops, and potentially problematic plant parts.
Internal links
Related plants
Chives
Belongs to the Allium genus and Amaryllidaceae family.
Leek Rust
Leeks are susceptible to leek rust.
Downy Mildew
Leeks can be affected by downy mildew.
White Rot
Leeks are susceptible to white rot, especially in damp conditions.
Cabbage
Cabbage is also a heavy feeder and benefits from similar nutrient supply.
Carrot
Carrots also prefer consistent moisture.
Sources
Public sources
- Wikidata entity
Wikidata · 2026-05-13
- GBIF species match
GBIF · 2026-05-13
- Deutschsprachige Wikipedia: Lauch (Gattung)
Wikipedia · 2026-05-13
- English Wikipedia: Allium
Wikipedia · 2026-05-13