Watercress has been rated by the Centers for Disease Control as the healthiest foodstuff of all, so I'd like to start growing some in a patio container. However its preferred location is the muddy bank of a cool stream. I have worked out this concept for an agitated water garden. It's not really hydroponics since soil is involved and the plant is continuously wet. It'll be a big project (for me) and there are some novel aspects, so I'd like to run this idea by the experts here for a sanity check. Background: Watercress can tolerate occasional submersion, needs fresh water, and prefers slight alkalinity. It's essentially an annual, but can be grown easily from cuttings. It can be harvested continuously, and it's supposedly easy to grow. References disagree about how much sun it needs or can tolerate, so it seems it'll handle anything from dappled shade to full sun. My front patio gets morning and late afternoon sun. I'm in Southern California, so heat is a concern but not frost Preparation: I'll get a medium sized (17" diameter) cylindrical Mexican terra cotta pot, made of fairly thick clay. I'll insert fittings into the drain leading to a short hose and valve. I'll use bricks attached with mortar to raise it off the ground. Inside, I'll coat the bottom of the pot with mortar/grout, perhaps going partway up the sides, in order to reduce water loss. The pot would be placed among other planted containers to provide a little extra shade. The watercress will be planted in a 3.5 gallon food-grade bucket, with many holes drilled into the sides and bottom. It'll be lined with fiberglass fly screen. The bottom half will be filled with perlite, then a layer of moss, then a top layer of a mix of sterile compost and perlite. It might be topped with a layer of small gravel to keep the soil in place. (I'm also thinking of nesting that bucket into a second bucket, also full of holes, which would support a shelf holding an inch of gravel that would cover the gap between the buckets and the clay pot, serving to shade the open water area and block bugs/debris.) (The inner bucket might be divided into quarters with plastic sheets to allow partial replanting.) (I might paint any exposed parts of the buckets, since they aren't UV resistant.) Process: The cultivation process will start with inserting cuttings into the prepared bucket. The pot will be filled with tap water. Once a day, or whenever I pass by, I'll lift the bucket out of the pot and drop it back down to provide intermittent agitation. Once or twice a week, when I water the other patio plants, I'll drain the pot, reusing the water for other plants, and refill. Once a quarter, or as needed, I'll restart the planting with fresh compost and fresh cuttings. (Or, if the bucket has been divided, I could replant each segment individually so that there's less disruption.) I think the compost will provide sufficient nutrients, but I can add soluble fertilizer if necessary. Questions and concerns: Does this sound crazy? I'm hoping the terra cotta pot might help cool the water through evaporation, but I don't want to lose so much water that it empties in less than a week or creates puddles. My biggest concern is that the terra cotta pot will somehow disintegrate or dissolve if kept constantly wet. Other concerns include water chemistry and temperature, leaching chemicals (I'm hoping I've avoided that by the choice of materials), integrity of the soil during agitation, and pollution from the adjacent road. Any feedback would be appreciated. I'm moving ahead with this project. I've been testing the water-holding capacity of the terra cotta planter. After soaking up almost a gallon of water into its thick walls on the first day, it hasn't lost much water, despite being open at the top and despite hot weather. The water is about 10 degrees cooler than the water in an impervious container. I expect that as minerals clog the pores it will become more impervious and give less cooling. There's already a light mineral frosting on the outside. I've also been testing the watercress in a small pot submerged in a larger pot full of water. The perlite added to the soil was a mistake - it floats and makes a mess. Also, using perlite to fill the bottom half made the pot top heavy. For my next iteration I've switched to expanded clay pellets from the hydroponics store. After soaking, they don't float (and look nicer). I also added some river rock at the bottom for ballast. The watercress itself is doing very well. The temperatures have been in the low 90s, so they look ready to bolt but haven't yet. They seem to handle the full morning sun w/ afternoon shade OK. The leaves darkened noticeably when out in the sun - they must be raised in a greenhouse. There's considerable new growth - they doubled in size in a couple of weeks. I've worked out a way of tying a wide collar of fly screen material around the rim of the inner pail to shade the open water between it and the outer pot, and to minimize mosquitoes. It may look funny but it's the simplest solution I've found. The principle remaining challenges are to find 3.5 gallon buckets at a reasonable price, and to apply mortar to the inside bottom of the planter.
Watercress has high value in nutrition, proteins and consumed by humans. But it can be suffocate fish life if covered most of the water surface having aquatic life.
I'm very interested in your experiment. i hope you have a good crop. i wouldn't mind doing something like this.
Teach us what you learn. I have never grown it or even eaten it... So I would be interested in learning about it.
I had been thinking of planting watercress recently. Are you starting your plants from seed or cutting? Seeds are not available here and the only way to get the plant is buying it from the market and planting the vines. I just throw my first batch into the composts because they rotted. I tried rooting them in water and I changed it daily but failed. Watercress here is farmed in the highlands because of the cool weather and in clean running water stream. Good luck and welcome!
Good Luck! I've never given thought to raising it but it grows in several of the streams around my area so there is no reason to. Even with it being readily available I have never tried it. After this post I think I should go on a hunt and at least give it a taste.
You are so lucky 2ofus to have them naturally. I am sure there will be second, third and many more trips there after tasting it.
