Saturday, 15 November 2014

How to grow Water Cress

People always tell me how much they love watercress (Nasturtium officinale) yet I don't know anyone who grows it, they are all too scared that it would be too difficult.  Everywhere I read says that water cress is difficult to grow.  Many places claim that water cress requires crystal clear water and that without flowing water it will not grow.  This is simply not the case, water cress is easy to grow if you have water, sunlight and soil.

I have wanted to grow water cress for years but was scared that it would not go well.  Having no one to ask adds to the fear that it would be difficult to grow.  Having never grown watercress meant that I had also never eaten it.  I was very curios about eating watercress so decided to bite the bullet and grow some.  One day I ordered some water cress seeds from ebay (something I never like to do as there is no guarantee with seeds, but it was so cheap it was worth the risk) and decided to give it a go.  I tried to grow it in a few ways and surprisingly all of them grew well.  It grew so well and was so simple that I thought I should write a post about it and explain what I did so that hopefully some other people will also give it a go.

Watercress starting to flower

Watercress is meant to be a perennial semi-aquatic vegetable.  Mine appears to be perennial, but then it self seeds so well that I am not certain that this is the case or if it forms a self sustaining population of annuals.  Regardless I always have some growing with minimal effort on my behalf, which is what I want.  Watercress is one of the oldest known vegetables, many of the older vegetables are semi-domesticated and can be a hassle to grow or harvest or eat or even have issues with edibility due to toxins.  While watercress could benefit from some serious breeding work to increase the size of the leaves, other than that it seem pretty good.  It is probably not great to eat in huge amounts, but I dare say one would eat a ridiculous amount before any problems would be noticed.  I don't think any brassica is fantastic to eat in huge amounts so it is certainly no worse than any of the others that people eat every day.  It handles cold weather, hot weather and does not appear to have any noticeable daylength sensitivity issues.

One place I grew watercress was in a fish tank as part of a mini aquaponics tank at work.  Water cress is clearly well suited to such life and performed well.  It appears that the only limiting factor here was sunlight, unfortunately my tank does not get quite enough light for it to perform as well as it should.  That being said it did well and cleaned the water well due to its rapid growth rate.  It did not take over the way mint does which is another bonus.  Unfortunately I did not take any pictures of this, it really does get very lush very fast with aquaponics.

Watercress getting leggy producing seed pods

Another way I grew it was in punnets.  I planted some seeds into a punnet of soil and kept this punnet in an icecream container with shallow water.  This was the simplest way to grow it that I could think of but I had doubts that it would grow using this method as the water is far from running.  I also grew some duck weed on top of the water (I like duckweed), this would lower the dissolved oxygen in the water so added to my doubts.  This grew incredibly well, these plants have since flowered and produced seed which I now need to collect and clean.  If I had limited space I would grow watercress in this way as it is so simple and productive.  The pot could be sized up or down to meet your needs and the ice cream container could be replaced with any container that holds water that is an appropriate size.

Watercress growing in a punnet, the duckweed is also growing well
I have taken cuttings from the plants I was growing and put them in a glass of water.  In a few days they all grew roots at each node.  I tried to float a plant in some water in a fish tank and see if it would grow without soil.  Short term this went very well but eventually it all died off.  The lack of adequate sunlight was certainly a factor here but I think that water cress probably needs soil.

I am currently trying to grow some watercress in a bucket of soil that has a few cm of water on top of it in a similar way to water chestnuts and duck potatoes.  I took a cutting from the existing plants and have planted it in the bucket.  It is still early days but so far it appears to be growing well.  It has survived some frost as well as a few days with temperatures in the low 40's so is proving to be far more hardy that I would have expected.  I will try to remember to update this after they have been growing for a few months, if they do grow in this way it is even easier than the ice cream method above.

At this stage I do not sell watercress seeds but I may do so in the future if I ever get around to collecting enough seed.  If I do they will be listed on my for sale page with all the other perennial vegetables, heirloom vegetable seed and herbs that I sell.  Once you have some growing it is simple to keep it growing and propagate by taking cuttings.

UPDATE: the original plants were eaten out by slugs/snails/something in one night.  It seems odd they have grown for so long with no problems at all but then are completely gone in one night, but there is not much that can be done now.  I think it may have been water snails, but do not know for sure.  The cuttings growing in the bucket are so far untouched and are continuing to grow well.  This bucket has no water snails.

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