Grow Spaces
Kratky on a Kitchen Windowsill
A windowsill is the simplest place to start with the Kratky method: no lights, no pumps, and fresh herbs or greens within reach of where you cook.
What a Windowsill Gives You
A sill gives you free daylight, a steady indoor temperature and a spot you walk past every day, so problems get noticed early. What it doesn't give you is much room or, for part of the year, much light.
This is where we started too: we grow in mason jars indoors all year, and the windowsill is where most of those jars live.
Which Window to Use
Use the brightest window you have. In the northern hemisphere that is usually a south-facing window, then west or east. A north-facing window rarely gives enough light for leafy greens on its own.
Watch for signs of too little light: long, pale, stretched stems and plants leaning hard toward the glass. If you see that, move the jar to a brighter spot or add a small grow light (see Under Grow Lights in the grow spaces list).
What Grows Well
- Herbs: basil, mint, parsley, chives and cilantro all suit a single jar.
- Leafy greens: loose-leaf lettuce and other quick greens you can pick a few leaves at a time.
- Not a good fit: tomatoes, peppers and cucumbers. They need more light and far more water than a windowsill jar can hold.
Containers
Wide-mouth mason jars are ideal: they fit a standard net cup, they're cheap, and one jar holds one plant. Block the light from the solution by wrapping the jar (a sleeve, paint, tape or a sock all work). Light reaching the nutrient solution grows algae, which competes with the roots.
Fill the jar so the solution just touches the bottom of the net cup at the start. As the plant drinks, the level drops and the roots follow it down, leaving an air gap the upper roots breathe from.
Common Windowsill Problems
- Heat from the glass: a sill in strong afternoon sun can warm the jar a lot. Warm solution holds less oxygen, so shade the jar itself even if the leaves stay in the sun.
- Cold glass in winter: leaves touching a cold window can be damaged. Keep a small gap.
- Short winter days: growth slows right down. That's normal; a grow light fixes it if you want a steady harvest.
- Tipping over: top-heavy plants in narrow jars fall easily. Use a wider container or a tray.
Windowsill Checklist
- Brightest window available
- Wrapped jar or opaque container
- Solution touching the bottom of the net cup at the start
- Herbs or leafy greens, not fruiting crops
- Jar shaded from direct heat
