Answered by the Garden Voila editorial team · Updated
Frequently asked question
How often should I water vegetable seedlings, and how do I avoid killing them with too much water?
Answer
Seedlings do best when their soil stays evenly moist but never soggy. For most indoor trays that means checking every day and watering only when the surface feels dry and the tray feels lighter. Overwatering is the most common way beginners lose seedlings, because wet soil invites damping off, a disease that makes stems collapse at the base.
How to tell when to water
- Touch test: press a fingertip into the soil. If the top half inch is dry, it is time to water.
- Lift test: a watered tray is noticeably heavier than a dry one.
- Look at the plants: slight drooping with dry soil means water now. Drooping with wet soil means too much water or poor drainage.
How to water
- Use containers with drainage holes and never let seedlings sit in standing water for long.
- Water gently with a fine rose or mist, or pour water into the tray and let the cells soak it up from below for 10 to 15 minutes, then drain.
- Use clean, room-temperature water. University of Minnesota Extension recommends clean water at about 68–77°F, because cold water near 50°F slows growth and raises infection risk.
- Keep hoses and watering cans off the floor so they do not pick up pathogens.
Prevent damping off
University of Minnesota Extension explains that damping off is caused by soil-borne fungi and water molds such as Rhizoctonia, Fusarium and Pythium, and that cool, wet conditions, low light, overwatering and excess fertilizer salts increase it. Its prevention advice:
- Use fresh, sterile potting mix, not garden soil or old compost.
- Clean reused pots and trays by soaking them in a 10 percent bleach solution for 30 minutes.
- Keep soil warm, about 70–75°F indoors, with a heat mat if needed.
- Give seedlings 12 to 16 hours of light from grow lights, since a window alone is not enough.
- Do not fertilize until several true leaves appear, then use quarter-strength fertilizer.
Water needs change as seedlings grow
Newly sown seeds need constant surface moisture until they sprout, a light misting once or twice a day. Established seedlings with true leaves need less frequent but thorough watering. Before moving outdoors, give seedlings a week of hardening off, and expect to water more often outside because wind and sun dry pots quickly.
Signs of trouble
- Seedlings that fall over with thin, brown stem bases: damping off. Remove them, improve drainage and ventilation.
- Fuzzy mold on the soil surface: too wet. Let the surface dry and increase airflow.
- Yellow, leggy seedlings: too little light or too much water.
Source
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