Kratky Method FAQ

No. It uses no pump and no air pump. See Make a Kratky Garden.

Light makes algae grow in the water. See Step 1: Pick a container.

Every few days. See Step 4: Check the water level.

Lettuce and herbs are common first choices. See Plants to Grow.

A simple way to grow plants in water with no pump and no electricity. The plant sits above a container of nutrient solution, and its roots take up the water as they grow. See Start Here.

It is named after Bernard Kratky, a horticulture researcher at the University of Hawaii who developed ways to grow vegetables in water without pumps or power.

Because the plant drinks it. As the level drops, it leaves an air gap at the top where the upper roots take in oxygen. See Step 4: Check the water level.

No. Refilling to the top can drown the roots that live in the air gap. Add only a little, so the lower roots stay in the water.

No. Use a nutrient made for hydroponics. Soil fertilizer relies on soil life and can be missing elements a water-grown plant needs. See Step 2: Add water and nutrients.

Algae. It grows when light reaches the water. Cover the container better with foil, paper or a sleeve. See Step 1: Pick a container.

It may need more light, the nutrient may be too weak, or the pH may be off. Move it somewhere brighter and check the water. See Nutrients, pH and Safety.

It is stretching for light. Move it closer to a sunny window or under a grow light, and turn the container every day or two.

Not if you have a bright, sunny window. In darker homes, or in winter, a grow light helps a lot. Mount it securely, away from the water.

Fast leafy plants like lettuce and basil can often be harvested within a few weeks. Larger plants take longer. See Step 6: Pick and enjoy.

Yes, but they are harder. They need a much bigger container, plenty of light and support for the stems. Try a leafy plant first. See Kratky Vegetables.

Yes. Wash the jar, lid and net pot in hot soapy water, rinse the clay pellets, and start again with a new seedling.

No. The air gap at the top of the container gives the upper roots oxygen as the water level drops. That is why the Kratky method needs no pump and no power.

Most clean jars work. Wide-mouth mason jars are popular because a net pot fits the lid. Larger plants need larger containers, like buckets. Cover any clear container to keep light out.

Small, light balls of baked clay that support the plant in the net pot and let air reach the roots. Rinse them before use. They can be reused.

Fuzzy, branched roots near the top are usually air roots, which take in oxygen in the air gap. Long, smooth roots below are water roots. Both are normal. Brown, slimy, smelly roots are not: check the water temperature and the air gap.

One plant per jar is best, so each has enough water, light and room. A large tote with several holes in the lid can hold a few plants.

Many growers pour it on outdoor plants rather than down the drain. Check your local guidance, then wash the container and start again.

Very little. Look at the plant whenever you like and check the water every few days. There is no daily watering like a pot of soil.

Yes. A single jar fits on a windowsill or kitchen counter, and a few jars can supply fresh herbs and greens without a garden bed.