Kratky hydroponics for potatoes
Kratky Potatoes
Kratky Potatoes teaches home growers to grow potatoes with the Kratky method, a passive hydroponic technique that needs no pumps, no air stones and no electricity. We grow potatoes this way and share what we learn here.
This site is for home growers who want to grow potatoes without a garden bed. You might have a patio, a garage or a basement grow shelf, or you might just want to know whether a potato can grow in a tub of nutrient solution. It can, with a few changes that leafy greens don't need.
What the Kratky method is
The Kratky method was developed by Dr. Bernard Kratky, a researcher at the University of Hawaii. A plant sits in a net pot in the lid of a container filled with nutrient solution. As the plant drinks, the level falls and leaves an air gap. The upper roots take in oxygen from that gap while the lower roots keep drinking. You fill the container once, or top it up now and then, and nothing needs to run.
Dr. Kratky first described the method for lettuce, a short crop that can finish on a single fill of solution. A potato is a different job. It grows for two to four months and makes a much larger plant, so the same idea has to be scaled up: a bigger container, more solution, and small top-ups through the season instead of one fill and done.
For more on the method itself, and how potatoes fit into it, see the potato page on our main site, Kratky Method of Hydroponics.
Why potatoes need a different setup
Lettuce only needs leaves and roots. Potatoes also need somewhere to form tubers. Tubers grow on underground stems called stolons, and they form only in the dark. Light turns them green, and green potato skin contains solanine, which you shouldn't eat. So a Kratky potato container needs:
Depth
Room below the lid for stolons and tubers, above the falling solution.
Darkness
Opaque walls and a lid that blocks light.
A loose medium
Perlite or coco coir in the root zone, so tubers have something to form in.
Plenty of solution
A full-size potato plant drinks far more than a head of lettuce.
How the guides fit together
Start with how to grow potatoes without soil, which covers the full Kratky setup from seed potato to harvest. If you'd like to watch roots form first, how to grow potatoes in water begins with a jar on the windowsill and shows when to move the potato into a Kratky container. Potato varieties for Kratky growing helps you choose seed potatoes that suit a container, and its companion guide to russet potatoes covers the hardest common potato to grow this way. If you're deciding what to build, hydroponic potato systems compares the Kratky method with pumped systems such as deep water culture. When you're ready to shop, the list of Kratky potato supplies covers everything you need. Shorter articles on single questions, from harvesting to green potatoes, are listed on the Kratky Potatoes blog.
Where to grow Kratky potatoes
Potatoes are a cool-season crop. Outdoors, a patio or balcony works well in spring and again in autumn, as long as the container sits in full sun and doesn't bake against a hot wall. Indoors, a garage or basement shelf with a full-spectrum LED grow light works, and a cool basement helps the root zone. Wherever you grow, the container needs to stay dark inside and fairly cool.
Who Kratky Potatoes is for
Kratky Potatoes is written for home growers, not commercial farms. Many of our readers are new to hydroponics and want a simple first project with no pumps to buy. Others already grow lettuce or herbs with the Kratky method and want to try a bigger crop. Families and classrooms use the guides to sprout a potato in a jar of water and watch the roots grow.
Kratky Potatoes is run by Portside Marketing, LLC. Our team grows potatoes with the Kratky method, and we check growing figures against published sources, listed below, rather than guessing.
What to expect
Expect a smaller harvest than a good soil bed gives. Kratky potatoes are a project for learning and for fresh new potatoes, not a replacement for a field. Early varieties that finish in a shorter season are the easiest place to start.
The harvest is smaller because each container usually holds one plant, the basket has limited room for tubers, and the plant has to get through the season on the solution in one container. In return, there's no digging. At harvest you lift the basket and tip out clean tubers, and the medium keeps away the pests that live in garden soil. The leaves can still get the usual potato pests outdoors, such as aphids and Colorado potato beetles, so check them now and then.
Sources
Start here
Four guides take you from a jar of water to a full Kratky container.