The species of plants you can grow only in water, without any soil base, is truly amazing. So, if you are ready for a shift from the conventional gardening to this water gardening, start now.
The advantage here is that you don’t have to mess up with soil, or worry about regular plant watering, or changing weather seasons.
STEP BY STEP:
- Place remaining stem in a shallow dish of water (about 1/2 inch).
- Place on a window sill or under grow lights.
- Change water in bowl every 1 to 2 days.
- Watch your lettuce grow. It is truly remarkable how quickly the new shoots start. You’ll also notice that roots will start to grow on the bottom.
- After 10-12 days, your lettuce is going to be as big as it will likely ever get. No, it’s not going to be a full head of lettuce, it’ll be just enough to top a sandwich or make a small salad. But how cool is that!
- If you leave your lettuce beyond this point, it will become spindly and bitter as it attempts to produce seed. It won’t be pleasant to eat at this point. You’ll know it has reached this point when the leaves start turning a blue green color and/or the main stalk shoots up and leaves become less dense.
When choosing a container, opt for a narrow-mouthed container for an advantage: it can support the cuttings and keep them nearly upright. Yet, the mouth of the container shouldn’t be too narrow or tight-fitting around the cutting. The mouth of the container should allow free air flow since the roots have to breathe.
Steps from: http://www.gettystewart.com/how-to-regrow-romaine-lettuce-from-the-stem/