Hydroponic Potato Systems

What every hydroponic potato system needs

• A dark root zone where stolons can form tubers.
• Oxygen at the roots.
• A balanced nutrient solution at a slightly acidic pH.
• Enough depth and volume for a large plant.

Kratky (passive hydroponics)

The plant sits above a container of nutrient solution, and the falling level leaves an air gap for the roots. There are no pumps and no power. It suits home growers and small batches. Each container holds one plant or a few, and the solution has to last the season or be topped up carefully.

Deep water culture (DWC)

Deep water culture is similar to Kratky, but an air pump and air stone keep the solution oxygenated, so the container can stay full. It copes better with warm conditions, but it needs electricity and a little more equipment. See Kratky vs deep water culture for potatoes for a full comparison.

Ebb and flow (flood and drain)

A tray filled with medium is flooded with solution and then drained on a timer. The medium gives tubers a natural place to form, which makes ebb and flow one of the better active systems for potatoes. It needs a pump, a timer and a reservoir.

Aeroponics

Roots hang in a dark chamber and are misted with nutrient solution. Commercial seed potato producers use aeroponics to grow small, disease-free minitubers. It's the most technical option for a home grower, and a pump failure can damage the roots quickly.

Nutrient film technique (NFT)

A thin stream of solution flows along a channel past the roots. It works well for lettuce but leaves little room for tubers, so it's rarely a good fit for potatoes.

Wick systems

A wick draws solution up into a medium. It's simple, but it usually can't deliver enough water for a full-size potato plant.

The systems side by side

• Kratky: no power; tubers form in the basket medium; the easiest to set up; a good fit for potatoes in a deep container.
• Deep water culture: an air pump; tubers form in the basket medium; easy; a good fit, and better in warm weather.
• Ebb and flow: a pump and a timer; tubers form in a tray of medium; moderate; a good fit with enough depth.
• Aeroponics: a pump and misters; tubers form in a dark chamber; hard; a good fit for seed growers, demanding at home.
• Nutrient film technique: a pump; little room for tubers; moderate; a poor fit.
• Wick: no power; tubers form in the medium; easy; usually too little water for a full-size plant.

The growing medium matters more for potatoes

With lettuce, the medium only holds the plant upright. With potatoes, the medium is where the crop forms, so it has to stay loose, dark and evenly moist.

• Perlite is light and drains freely, so tubers form in airy medium. It can dry out at the top and float if flooded.
• Coco coir holds more moisture and stays dark. Choose a buffered coir, because unbuffered coir can hold on to calcium and magnesium the plant needs.
• A perlite and coco coir mix balances the two, and many growers use it for potatoes.

For a fuller comparison, see perlite vs coco coir for potatoes.

What Kratky does well, and where it struggles

Kratky's strengths are simplicity and quiet. There's nothing to plug in, nothing to fail during a power cut, and no noise in a living space. You can set up a container in an afternoon and leave it for a week at a time.

Its weak spots show up with long, warm seasons. Warm solution holds less dissolved oxygen, so in summer heat the roots in the solution get less air, and root rot becomes more likely. A big potato plant also drinks a lot, so the solution needs topping up more often than it would for lettuce. Starting early in the season, keeping the container shaded and choosing an early variety all help. If heat is a regular problem, compare Kratky vs deep water culture for potatoes.

Choosing a system

• If this is your first hydroponic potato, start with Kratky in a deep, opaque container.
• If your summers are hot, or you want to grow through warm weather, try deep water culture: the air pump keeps the roots supplied with oxygen.
• If you want several plants in one setup, ebb and flow gives them a shared tray of medium to form tubers in.
• If you want to experiment with small seed tubers and don't mind the extra equipment, try aeroponics.

Why we use the Kratky method

For a home grower, Kratky is the easiest way to find out whether hydroponic potatoes suit you. It's cheap and quiet, and it has no moving parts. Its limits are making one batch of solution last the season and keeping the root zone cool and dark, and choosing the right container deals with both.

The method comes from Dr. Bernard Kratky's research at the University of Hawaii, which he first published for lettuce. For the full background, read the original paper listed below.

Sources

• Kratky, B.A. (2009), "Three non-circulating hydroponic methods for growing lettuce," Acta Horticulturae 843