Your cabbage seedlings are strong, leafy, and eager to grow — but don’t rush them into the garden just yet. Indoor-grown seedlings need a gentle transition to the outdoor environment, or they risk transplant shock. That’s where hardening off comes in.
What Is Hardening Off?
Hardening off is the process of gradually acclimating seedlings to outdoor conditions like sun, wind, and temperature swings. Skipping this step can lead to:
- Wilting or scorched leaves
- Stunted growth
- Increased pest and disease vulnerability
When to Start Hardening Off
Begin hardening off about 7–10 days before transplanting, once:
- Seedlings are 4–6 weeks old
- They have at least 2–3 sets of true leaves
- Outdoor temperatures are consistently above 7°C (45°F)
How to Harden Off Cabbage Seedlings
- Day 1–2: Place seedlings outside for 2–3 hours in a shady, sheltered spot
- Day 3–5: Increase time outdoors to 4–6 hours, allowing dappled sun exposure
- Day 6–7: Leave outside for 8+ hours, including a few hours of full sun
- Final day: Leave them out overnight if temperatures remain safe
Tips:
- Bring seedlings inside if there’s wind, frost, or strong rain
- Water before and after exposure
- Watch for signs of sunburn or drooping
🌤️ AiFarming Tip: Our hardening-off scheduler gives daily weather alerts, step-by-step prompts, and custom timelines based on your sowing and transplant dates. We help you toughen up your plants without the stress.