Garlic
Allium sativum
Plant individual cloves in autumn for large summer bulbs. Hardneck varieties produce edible scapes that should be removed to encourage bulb growth.
Overview
Companion Planting
Good Companions
Carrot
Beetroot
Strawberry
Raspberry
Red Currant
Black CurrantBad Companions
Pea
Green Bean
Runner Bean
AsparagusToxicity
Garlic contains thiosulfates and organosulfur compounds (notably n-propyl disulfide) that can cause oxidative damage to red blood cells in dogs, cats, and horses, leading to hemolytic anemia. Cats are especially sensitive. Toxic effects are dose-dependent; small amounts may not cause symptoms, but repeated or large doses are dangerous. Safe for humans in normal culinary quantities. Listed as toxic by the ASPCA.
Planting Tips
1 cm of water per m² equals 10 liters. Use the Watering Calculator for exact amounts.
Care Tip: Mulch with straw or leaves to suppress weeds, retain moisture, and insulate cloves over winter. Remove scapes (flower stalks) on hardneck varieties to direct energy into bulb development. Harvest when the lower 3-4 leaves have browned but upper leaves are still green.
Common Pests
Onion Fly (Delia antiqua)
Symptoms: Yellowing and wilting of leaves. Larvae feed on roots and bulb base, causing soft, mushy tissue. Plants may collapse. Maggots visible in the bulb when pulled.
Treatment: Remove and destroy affected plants immediately. Apply entomopathogenic nematodes (Steinernema feltiae) to the soil as a biological control. Insecticidal drenches containing spinosad can be used in severe infestations.
Prevention: Use fine insect-proof mesh or fleece covers over crops during the fly's active period (May-June). Practice crop rotation (at least 3-4 years). Avoid damaging bulbs during cultivation as the scent attracts flies. Interplant with carrots to mask the scent.
Leek Moth (Acrolepiopsis assectella)
Symptoms: Small caterpillars mine into leaves, creating elongated windowpane-like patches and holes. Later instars bore into the stem and bulb. Frass (excrement) visible at entry points. Severely affected plants may rot from secondary infections.
Treatment: Hand-pick caterpillars and remove affected leaves. Apply Bacillus thuringiensis (Bt) spray when larvae are small. Destroy crop debris after harvest to eliminate overwintering pupae.
Prevention: Cover crops with insect-proof netting from April through September. Monitor with pheromone traps to time interventions. Remove and destroy plant debris at the end of the season.
Stem and Bulb Nematode (Ditylenchus dipsaci)
Symptoms: Swollen, distorted, and softened stems and bulbs. Leaves may appear stunted and twisted. Bulbs develop a spongy texture and may crack or rot. Infested cloves show brown rings when cut open.
Treatment: No effective chemical treatment for home gardeners once plants are infected. Remove and destroy all affected plants (do not compost). Hot water treatment of seed cloves (49°C / 120°F for 20 minutes) before planting can reduce nematode populations.
Prevention: Use certified disease-free planting stock. Practice a minimum 4-year crop rotation away from all Allium species. Avoid moving soil from infested areas. Clean tools and equipment between plots.
Common Diseases
White Rot (Sclerotium cepivorum)
Symptoms: Yellowing and wilting of leaves starting from the tips. Fluffy white fungal mycelium develops around the base of the bulb and roots. Small, round, black sclerotia (0.5-2 mm) form on the decayed tissue. Roots rot away and bulbs become soft and watery.
Treatment: No effective chemical cure for home gardens. Remove and destroy all infected plants and surrounding soil. Do not compost. Solarization of soil in warm climates may reduce sclerotia populations.
Prevention: Use only certified clean seed stock. Practice very long crop rotation (sclerotia can survive 15-20 years in soil). Avoid transferring soil from infested plots. Clean all tools and boots. Consider raised beds with fresh, clean soil in areas with known infestation.
Downy Mildew (Peronospora destructor)
Symptoms: Pale green to yellow patches on leaves, often elongated. Grey-purple fuzzy fungal growth appears on leaf surfaces in humid conditions. Leaves may collapse and die back from the tips. Bulbs remain undersized and do not store well.
Treatment: Remove and destroy infected foliage immediately. Apply copper-based fungicides (approved for organic use) or mancozeb as a preventive spray at first signs. Improve air circulation around plants.
Prevention: Ensure good spacing between plants for air circulation. Avoid overhead watering; water at the base early in the day. Practice crop rotation (3-4 years). Choose resistant varieties where available. Remove crop debris after harvest.
Garlic Rust (Puccinia allii)
Symptoms: Small, round, orange to reddish-brown pustules on leaves, mainly on the upper surface. Severely affected leaves turn yellow and die prematurely. Reduces bulb size and quality. Does not typically kill the plant but weakens it significantly.
Treatment: Remove and destroy badly affected leaves. Fungicide sprays containing tebuconazole or myclobutanil can reduce spread if applied early. Improve air circulation by thinning plants.
Prevention: Space plants adequately (15-20 cm apart in rows 30 cm apart) for good airflow. Avoid excessive nitrogen fertilization which promotes soft, susceptible growth. Practice crop rotation. Remove all Allium debris at end of season. Avoid overhead irrigation.