Originally posted May 3, 2013.
The Theory: You can re-grow lettuce in water.
The Verdict: It makes a cool science project for the kids, but it’s not something you would want to eat.
We noticed a post on Facebook telling friends to save the stump at the end of the lettuce and re-grow it in water. We wanted to know if it was true. Should we all start saving the end of our lettuce and put it in water, so that it will grow back?
To answer our questions, we reached out to Dr. Joe Kemble, Professor of Horticulture at Auburn University.
Dr. Joe Kemble
Dr. Joe Kemble: “The quick answer is yes, lettuce will re-grow, but it really comes down to having the patience to actually grow it. Lettuce can grow hydroponically, but water itself is not a good medium to grow things in. The types of roots that form in water are very different from the types of roots that form in soil. By itself, water does not contain any nutrients.
“In the case of lettuce, that stump at the bottom of the lettuce that the leaves are attached to is the stem – it’s just greatly compressed. In this case, you’re relying on vegetative buds that exist in the stem to break and start growing again. There are no nutrients within the root or within the stem to help with regrowth, so this method will not make a whole head of lettuce again. You’d have to provide sun and nutrients like you were growing it hydroponically.
“For the average person to put this on their kitchen counter and expect their lettuce or celery to grow, it’s probably not going to happen. The taste wouldn’t be very good, because it will be greatly stressed due to the fact that it doesn’t get much sunlight, and it doesn’t have any nutrients. I wouldn’t suggest sticking it in the sun, unless you were actually going to try to provide some nutrients to the plant. There are a lot of recipes you can follow online if you want to try to grow lettuce or celery hydroponically, but basically, regrowth just doesn’t work very well.
“Onions are in a different family from lettuce. They’re a bulbing crop, and you will get regrowth but it depends on the type of onion.
If you try to re-grow a head of lettuce hydroponically and the water it's in turns blue, this is a sign that the lettuce you originaly purchased was grown hyrdoponically. "The blue is actually coming from the nutrient solution that the lettuce's roots were grown in. Most of the nutrient mixes are dyed blue (or green or red) so that growers can see that the material is flowing through the system. The day is a harmless food-grade dye."
“When it comes down to it, these are nice experimental projects for kids, but they’re just not realistic for food. Growing food by putting it in water once it’s already been harvested, and therefore greatly stressed, is not going to work very well. It’s a quality and taste issue. It’s going to be of low-quality taste because it was not grown under optimal conditions.”