Winter is a good time to grow indoors, but shorter days and cooler rooms change how a hydroponic system behaves. The two things to watch are light and temperature.
Why light changes in winter
Daylight is weaker and shorter in winter, even on bright days. Plants that grew well on a sunny windowsill in summer may stretch, go pale or grow slowly when the light drops. Many growers add a grow light on a timer to keep the daily light period steady. Choosing a light is covered in our lighting guide.
Keeping the solution warm enough
Cold rooms can cool the nutrient solution, and cool water holds more oxygen but roots slow down and take up less food. Keep the reservoir away from cold windows, draughts and exterior walls. A small insulated sleeve around the reservoir can help. Do not heat the solution to a high temperature, because warm water holds less oxygen and encourages root problems.
Adjusting your routine
Plants usually drink and grow more slowly in winter, so the solution may last longer. Keep checking it anyway. Test the pH after each top-up, because the balance still moves over time. Look at the leaves and roots every week, and adjust the light or temperature before the plants show stress.
A simple weekly checklist
- Check the light timer and the height of the light.
- Test and adjust the pH.
- Top up with plain water if the level has dropped.
- Look for pale, stretched or yellowing leaves.
- Check the roots for brown or slimy patches.
Keep learning
Related guide: Lighting for Hydroponic Plants. You can also read the guides hub or the FAQ.
See also: How to Test and Adjust pH in a Hydroponic Reservoir.