Fan for seedlings and damping-off
Utah State Extension recommends a small fan at plant level, used gently, to help prevent damping-off.
What the source says
- Damping-off is a fungal problem that cool, moist conditions favour.
- To prevent it, let the soil dry between waterings, space plants, and place a small fan at plant level.
- Brief, gentle airflow one to several times a day for 5 to 10 minutes may strengthen seedlings.
- Too much direct airflow can damage seedlings and make them need water more often.
- Remove the humidity dome once about 50 percent of seeds have germinated.
Setting it up on a shelf
- Choose a small fan that can run on low, or one with speeds. Aim for movement of the leaves, not a strong blast.
- Point it along the shelf or bounce it off a wall, so seedlings get gentle air and are not hit directly.
- Use a timer if you want the short bursts the source describes. A plug-in timer for the lights does not suit this, because the fan needs a different schedule.
- Check the soil more often. More airflow dries the tray faster.
If damping-off has started
The sources describe prevention. Utah State does not describe a cure for seedlings already affected. Seedlings that have collapsed at the soil line generally do not recover, so the practical step is to improve airflow and watering for the rest of the tray.