Starting vegetable seeds indoors

Warmth-loving crops with a long season, such as sweet peppers, chillies, tomatoes and celeriac, would not ripen in time if sown outdoors. That is why they are started indoors and planted out later.

The right time

Starting too early is the most common mistake. In February the light at the window is usually too weak, and seedlings grow tall and spindly. As a rule of thumb: peppers and chillies from mid-February, tomatoes from March, cabbage and lettuce from March. The sowing calendar works out the dates for your climate.

Light and warmth

• Germination: many fruiting vegetables germinate best at 20–25 °C; lettuce and cabbage need less (15–20 °C).
• After germination: keep the seedlings bright and a little cooler so they stay compact.
• Light germinators such as lettuce, basil or celeriac are not covered with soil – just press them in and keep moist.

Compost and containers

Use low-nutrient seed compost rather than potting compost; fewer nutrients encourage root growth. A tray with a clear lid keeps the moisture in – air it daily to prevent mould.

Pricking out and hardening off

As soon as the first true leaves appear after the seed leaves, move the seedlings into individual small pots (pricking out). Before planting out, get them used to the outdoors for one to two weeks by putting them outside for a few more hours each day.

Note: The dates apply to Central Europe (e.g. Germany, Austria, Switzerland, the Benelux countries, Poland, northern France). In warmer regions such as the Mediterranean, many dates come earlier; in Scandinavia or at high altitude, later. Use “Climate” and “Last frost” to adjust the calendar.

Sources

• Bavarian State Research Center for Viticulture and Horticulture (LWG), Bavarian Garden Academy: vegetable garden guides (in German) – lwg.bayern.de/gartenakademie
• Deutscher Wetterdienst (DWD), German weather service: phenology and the “Ice Saints” (in German) – dwd.de, phenology
• Federal Centre for Nutrition (BZfE): seasonal calendar for fruit and vegetables (in German) – bzfe.de
• Seed packets and variety descriptions from seed producers – the information on the packet always takes precedence.

The dates in the calendar are typical ranges for Central Europe. Variety, location, soil and weather can shift them. As of November 2026.