When to Sow Onion?
Onion – popular seasoning vegetable. Resistant to most pests. Below you'll find exact sowing dates, growing requirements, recommended fertilization and companion plants — all from our plant database. Click the button to see dates personalised for your region in the interactive planner.
Sowing dates – 🧅 Onion
| Sowing dates | Onion |
|---|---|
| Indoor sowing | — |
| Transplanting | — |
| Direct sowing | Mar–Apr |
| Harvest period | Jul–Sep |
| Days to harvest | 120 |
| Spacing | 10 × 25 cm |
| Sowing depth | 1 cm |
| Days to germination | 10 |
Growing requirements
Onion (Allium cepa) belongs to the family: Lily. The requirements below come straight from the app database – you will see the same values on the plant card in Gardener Planner.
| Sunlight | high |
| Water | low |
| Soil | loamy |
| pH | 6–7 |
| Family | Lily |
Fertilization (NPK)
Approximate nutrient demand. For precise doses, test your soil first – the NPK fertilizer calculator will do the math for you.
| Nitrogen (N) | medium (10–14 g/m² per season) |
| Phosphorus (P) | high (60–80 mg/l in soil) |
| Potassium (K) | high (175–225 mg/l in soil) |
Companion planting
Good companions reduce pests and diseases and make better use of bed space. Click a vegetable to see its sowing dates.
Good companions: Beetroot, Zucchini, Carrot, Cucumber, Parsnip, Parsley, Tomato, Leek, Lettuce
Bad companions: Beans
Plan your Onion in the app
Gardener Planner lets you match sowing dates to your climate zone, track progress and plan crop rotation across your whole garden.
Open Gardener Planner →Frequently asked questions
When to sow Onion indoors?
Onion does not need to be started indoors — sow directly into the garden.
When to transplant Onion?
Onion is direct-sown and does not require transplanting.
When to harvest Onion?
Harvest Onion from Jul–Sep (approx. 120 days from transplanting/germination).
What spacing and sowing depth?
Spacing: 10 × 25 cm. Sowing depth: 1 cm. Days to germination: 10.
What to plant next to Onion?
Good companions: Beetroot, Zucchini, Carrot, Cucumber, Parsnip, Parsley, Tomato, Leek, Lettuce. Bad companions: Beans.
When to Sow? – Sowing dates for every vegetable
🍅 Tomato · 🥕 Carrot · 🥒 Cucumber · 🥒 Greenhouse Cucumber · 🥬 Lettuce · 🫑 Pepper · 🥔 Potato · 🥬 Cabbage · 🫘 Beans · 🫛 Peas · 🥬 Radish · 🥒 Zucchini · 🎃 Pumpkin · 🧄 Garlic · 🥬 Leek · 🥬 Spinach · 🥬 Beetroot · 🥦 Broccoli · 🥬 Cauliflower · 🥬 Kohlrabi · 🥬 Celery · 🌿 Parsley · 🥕 Parsnip · 🍆 Eggplant · 🌽 Corn · 🍠 Sweet Potato · 🥬 Asparagus · 🥬 Turnip · 🥬 Brussels Sprouts · 🥬 Kale · 🥬 Swiss Chard · 🥬 Arugula · 🥬 Endive · 🥬 Rhubarb · 🌿 Horseradish · 🌿 Fennel · 🥬 Artichoke · 🥬 Okra · 🥬 Watercress · 🌿 Chives · 🌿 Basil · 🌿 Dill · 🌿 Mint · 🌿 Thyme · 🌿 Rosemary · 🌿 Sage · 🌿 Oregano · 🌿 Cilantro · 🌿 Lovage · 🥬 Sorrel · 🫛 Broad Beans