Seeds & planting
Harden off seedlings before planting out
Choose mild conditions and start in sheltered light shade for a short daytime visit.
When to do it
Before moving protected plants permanently outdoors, when weather is suitable for that species.
What you need
- Sheltered outdoor spot
- Movable trays
- Forecast
How to do it
- Choose mild conditions and start in sheltered light shade for a short daytime visit.
- Bring plants back under protection before cold nights or damaging weather. Keep the root ball moist without deliberately wilting it.
- Increase outdoor time and light gradually over roughly two weeks; slow down after scorching or persistent wilting.
- Introduce the conditions of the final site in manageable stages. Tender plants still need protection from frost even when hardened.
- Plant out only when the crop’s zone window and actual conditions both suit it. Water after planting and inspect the next day.
What success looks like
- Leaves cope with a full day at the intended exposure.
Watch out for
- Moving a tray straight from indoors into hot sun.
- Assuming hardening makes a tender plant frost-proof.
Related help
Space and transplant seedlings
Check the mature spacing in the plant guide or variety label.
Give vulnerable plants temporary shade
Reduce harsh afternoon sun while keeping air moving.
Sources and review
Checked 24 September 2026. Source-checked editorial guidance; not field-tested or independently reviewed by a horticulturist.