Glossary

‘Hardening off’ is the process of gradually getting young plants used to outdoor conditions. Plants that start their life in protected spaces (indoors or in a greenhouse) are sensitive to temperature differences, wind and direct sunlight. Hardening off allows them to develop more stable cell structures and resilient leaves.

Why hardening off is important

✔ Prevents stress reactions like sunburn or growth impairments.
✔ Strengthens the plant tissues and reduces the risk of environmental damage.
✔ Builds resilience to wind, temperature fluctuations and extreme weather conditions.

When to harden off your plants

• 1–2 weeks before transplanting outdoors.
• Especially important for warmth-loving plants like tomatoes, peppers and squashes.

Hardening off – how to do it

1. Gradually get the plants used to being outdoors:

• • From day 1 place in a sheltered, semi-shaded location for a few hours.
  • Increase the time spent outdoors day by day.

2. Introduce wind and temperature variations:

• • Place in less sheltered locations after a few days.
  • Also gradually introduce cooler temperatures (no lower than 10 °C).

3. Increase direct sunlight only slowly:

• • Stand in sunlight only in the morning or evening to start with.
  • After a week or so the plants will be able to cope with full sunlight.

 4. Adapt your watering pattern:

• • Watering less will stimulate the roots to find the moisture they need.
  • Avoid extreme temperature variations (no cold water).