Can You Grow Kratky Without Grow Lights, Using Sunlight Only?
Plan the crops around the season. Kratky without grow lights works through spring, summer and fall in a bright spot, and more slowly in winter. Grow greens in the cool, bright months, warm-season crops in summer, and expect little growth in the darkest weeks of winter.
Without power for a light, sunlight is the only source, and it changes through the year. The trick is to grow what that light suits at the time, rather than fight it.
Find the Best Light
At a cabin, shed or anywhere without power, the brightest spot is usually a south-facing window or an outdoor spot with open sky to the south (in the Northern Hemisphere). Watch where the sun falls through a day. Trees that shade a spot in summer may let light through in winter once their leaves drop, and the low winter sun reaches farther into a room.
Season by Season
- Spring: lengthening days and cool temperatures. The best season for lettuce, spinach and other greens.
- Summer: long days and heat. Basil, peppers, tomatoes and cucumbers do well in large containers; lettuce bolts unless shaded. Keep containers shaded so the solution stays cool.
- Fall: another good window for greens as temperatures fall. Start them in late summer so they size up before the days get short.
- Winter: short days and weak light. Greens grow slowly in a bright window; outdoors, containers can freeze.
Planning Crops
- Start greens in early spring and again in late summer for a fall crop.
- Start warm-season crops indoors in spring, then move them out after the last frost.
- Sow a few plants every couple of weeks in the good seasons, so something is always ready.
- In late fall, pick the brightest window for the containers that will spend winter inside.
Making the Most of Daylight
- Keep windows clean.
- Put containers right against the glass, or outdoors where nothing shades them.
- Use a white wall or a reflective board behind plants to bounce light back.
- Turn containers every few days so plants grow evenly.
Winter Without Lights
Winter growth is slow, but greens still grow in a bright window. Lettuce that takes five weeks in spring may take two months. Keep containers away from freezing glass and cold floors. In an unheated cabin, the solution may freeze; the freezing article covers what happens and how to protect containers.
Checking Without Power
You can do everything with simple tools: a ruler or a mark on the container for the level, and a liquid pH kit or strips. The pH without a meter article explains how.
Common Mistakes
- Starting lettuce in midsummer heat.
- Expecting summer growth in December.
- Leaving containers on a cold floor or glass in an unheated building.
Common Questions
Can Kratky grow in winter without a grow light?
Yes, in a bright window, but slowly. Leafy greens are the best choice. Keep containers above freezing.
What grows best with sunlight only?
Lettuce and leafy greens in spring and fall; basil, tomatoes, peppers and cucumbers in summer.
Do I need power for anything in Kratky?
No. Kratky needs no pump or air stone. A light is the only thing that uses power, and sunlight can replace it.
Related guide: growing Kratky off-grid.
Related article: Can Kratky Grow Emergency and Preparedness Food?