The Kratky method, developed by B. A. Kratky at the University of Hawaii, is a non-circulating hydroponic technique. A plant in a net pot sits in a lid over a tank filled with nutrient solution. As the plant drinks, the level falls, leaving an air space; the upper roots adapt to breathe in that humid air while lower roots keep drinking. No pump, air stone or electricity is needed.
In practice
Kratky works very well for lettuce and herbs. For cannabis, which drinks large volumes and is grown for months, it needs a big container (tens of litres per plant), a starting EC and pH set carefully, and top-ups with weak solution rather than refilling to the top, which would drown the air-adapted roots. Warm solution and stagnation make root rot more likely. Some growers use it for seedlings or small autos, or as a learning tool.
Don't confuse with
- DWC: actively aerated with an air pump.
- Wick system: passive, but feeds a medium through a wick.
A net pot is a plastic cup with slotted or mesh walls that holds a plant and its medium in a hydroponic lid, letting roots grow through into solution.Air-filled porosity is the share of a container's volume that holds air rather than water after it has drained, a key factor in root oxygen and overwatering risk.An air stone is a porous diffuser connected to an air pump that breaks air into fine bubbles in a nutrient solution, mixing it and helping maintain dissolved oxygen.EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.Decay of roots by pathogens such as Pythium, Fusarium, Rhizoctonia or Phytophthora, usually triggered by low oxygen, heat and waterlogging around the roots.DWC (deep water culture) suspends a plant's roots in an aerated nutrient solution, typically in a bucket with a net pot lid and an air stone.A wick system is a passive watering method in which an absorbent cord draws water or nutrient solution up from a reservoir into the medium by capillary action.Hydroponics is growing plants without soil, feeding roots a complete mineral nutrient solution either directly in water or through an inert medium.Dissolved oxygen (DO) is the amount of oxygen gas held in water or nutrient solution, measured in mg/L, and roots need it to respire and take up nutrients.
