Garden Cress, Upland Cress, Winter Cress, Curly Cress, Yellow Rocket, Pepper Grass, which is the real watercress and how does it grow? Is it an annual or a biennial? Can it be grown hydroponically?
Ever since the local paper published an article on hydroponic growing forty odd years ago, I have wanted to try growing watercress. Of course, our habit of moving frequently, and living in upstairs apartments did not make that seem feasible...until now.
Last summer we found live watercress at the Whole Foods Market and suspended some of it over a long shallow container to see if we could keep it alive longer by leaving the roots on and growing it hydroponically. We were on vacation, so we only needed to extend the life for a month. The live plants did not have a tag indicating what kind of watercress it was, and although it looked rather different from the plants that grow wild in a creek near our vacation home, we didn't think much then about the difference.
We dissolved some Miracle Grow in water and poured it into the container, a standard ice cube bin, with a fill line marked on the side, and a rectangular piece of flexible cutting board resting on top as a cover. We punched holes for several small plastic net pots such as are obtainable for about 25 cents each at hydroponics suppy stores and a small hole to feed fish tank tubing through. Then we put an air stone in the water, connected to one end of the tubing and a check valve from the pet store at the other end and that in turn went to a small air pump. This apparatus took care of aerating the roots, so all I had to do was top off the water every few days.
We had some other plants under grow lamps on the kitchen counter, so we positioned the cress nearby to enjoy the spill-over from the lamps. We added a few leaves to salad and tried them in egg dishes, and sent away for a seed packet with the idea of growing some of this "watercress" in our winter garden when we got back to our desert home. Once there, I dutifully planted the seeds and waited...and waited...and waited. Finally, about the time we were harvesting our first salads from the rest of the plants started on the same day, the watercress grew a few tiny little leaves. It didn't look anything like the cress we had enjoyed on our summer trip, but it did eventually grow out a few inches and tasted quite good. To my delight, though, the variety I planted, Nasturtium officinale, is a periennial and roots easily from cuttings.
When searching for a faster growing and less fussy plant to grow , I found Lepidium sativum, commonly called garden cress or peppergrass, although the latter term can be used for any of over 200 plant species in the genus Lepidium. This one is also a perennial. Although one variety of the sativum, called Persian Broadleaf Cress looked quite similar to our supermarket cress, we were not able to confirm that it was the same thing, so we just forgot about it for the time being.
To our delight, however, the produce section of our local Safeway store just started carrying Live Watercress, grown hydroponically by Hollandia Produce under their LiveGourmet label. The package gave upland cress as the subheading under watercress. An online search revealed that there are several plants commonly known as upland cress, but a Wikipedia article confirmed my guess that this life plant was Barberea verna, also known as Early Yellow Rocket, Early Winter Cress, or Land Cress. It has a relative called Barberea vulgaris, known as Yellow Rocket, Bittercress, and Herb Barbara, and which is generally regarded as a weed.
Since this watercress, which I should perhaps call land cress instead, is cold-tolerant, I decided to try growing it in one of the simple manual ebb and flow containers I fabricate out of recycled juice containers filled with hydroton rocks, and if it thrives, set it out on the porch when the weather cools off a bit more, as our winter lows rarely go below 42F.
My system consists of three nested juice bottles, with the tops cut off. I particularly like the bottles they use to package Fiji Water and Naked or Bolthouse Juice. The outer container, which does not come into contact with the nutrient solution should be opaque and can be made of nearly anything, even a small paper bag. It serves mainly to keep direct light off the inner container. The inner one has holes drilled in the bottom for drainage and is filled with small to medium grow rocks and nests inside the middle container, which is marked with a drain line and a fill line. In order to facilitate lifting the inner containers out for rinsing, I attached handles made from pipe clearners to the top of each of the two inner containers. The middle container holds liquid nutrient solution, which is basically water with some sort of fertilizer dissolved in it. For this experiment I am using a weak solution of General Hydroponics Flora Series liquid nutrients.
Once a day, as I'm checking the fill levels on the various planters we use to grow our indoor salad herbs, tomatoes, peppers, and other hydroponic houseplants, I simply lift each inner container out and allow it to drain completely into a measuring cup or other handy utensil. Then I pour the solution back into the middle container, adding water and/or more nutrient solution until it is even with the drain line, and then carefully lower the inner container (which holds the rocks and the plant) back into the nutrient solution observing the solution rise to the fill line. Every week or two, time allowing, I take the inner container to the sink and run fresh water over the top of the grow rocks to flush them, and also wash out the middle container.
This is the first time we have tried this method, but it has worked well with other brassicaceae, such as Asian greens. At this writing, the plant is showing no signs of stress. Since this variety of cress is a biennial, we will not be seeing its pretty yellow flowers, and presumably will have to start the plant over from seeds from time to time. That is fine, as when we migrate to our summer place all existing plants must be eaten up and started over on the other side.
Being able to buy live plants in the supermarket, then, suits us just fine. In addition to spicing up salads, land cress can be boiled or sauteed or even added to pasta sauce along with basil or spinach.
