Ventilate the greenhouse, shade it, and keep the containers themselves out of the sun. Warm nutrient solution holds less oxygen and encourages root rot, and a still container in a hot greenhouse warms up quickly.
Ventilate
Open vents and doors early on warm days, before the heat builds. Automatic vent openers, which work without electricity, are worth considering for a greenhouse you can’t check every day.
Shade the Greenhouse
Shade cloth or shading paint on the glass cuts heat as well as light. Most leafy greens grow fine with some summer shade.
Shade the Containers
- Put containers on the floor or under benches, where it’s coolest.
- Use white or reflective containers, or wrap dark ones.
- Keep the leaves in the light but the container out of direct sun.
Use Bigger Containers
A large volume of solution warms more slowly than a small one. In summer, a big tub is more stable than a row of small jars.
Watch the Roots
Healthy roots are white or cream. Brown, slimy roots and a bad smell are signs of root rot, often from warm solution. Move affected plants somewhere cooler and start with fresh solution.
Related guide: growing Kratky in a greenhouse.
