Scott O'Brien

Projects, Ramblings and Resources of my (online) life

Hydroponic Kratky Lettuce Attempts

This year i’ve decided to start playing with Hydroponics as a hobby. I’ve been interested in starting with the Kratky Method of gardening. The idea is to grow lettuce in mason jars and see how growing without soil does. I’ve previously enjoyed growing my own alfalfa micro-greens, so this is the next obvious step.

Attempt #1

These didn’t go so good. I had planted some seedlings in Rockwool, and left them in a container out in the sun to act as a mini-greenhouse. In the SF Bay area getting towards winter, I feel it may have been too cold, and most of my seedlings ended up dying off. The mason jar didn’t do so well once it was planted either. ~6 weeks in I’d call my first attempt a failure.

Attempt 2

  • 22nd November: Planted seeds in Rockwool
  • ~29th November: Started moving to a half-nutrient watering solution
  • 5th December (+13 days): Moved to mason jars

I decided to try and move indoors. I got a 150 Watt LED bulb (5000K) to provide the light, and turned my old proofing box to a simple 9 hour a day timer. I find this is a good time of a year for indoor growing as the temperature with the grow light on is between 14c and 23c of a day. The ideal temperature for growing is 13-18c, so I’m curious to see how they go indoors in the warmer climate.

I’m using this guide for measuring the lettuce levels:

  • PH: 5.5-6.5
  • EC: 0.8-1.2

note: Work in progress. Will update once plants have had more of a chance to grow.