How to Grow Watercress the Easy Way

I have been growing watercress (Nasturtium officinale) for a little over ten years, I wrote a blog post on it in 2014.  It is a simple plant to grow, and people seem to rave about watercress, yet for some reason people are told it is difficult to grow.  I am happy to say this is not the case, and watercress can be grown and be productive in very little space. 

Some people assume there is some connection between watercress and nasturtium (Tropaeolum majus).  Even though the Genus of one and the common name of the other are the same, the two are not closely related in any way.  Garden nasturtium is native to Peru, while watercress is native to Eurasia.  Apparently the garden nasturtium got its common name because it produces an oil that is meant to be similar to watercress.  

Occasionally people contact me to ask about growing water cress, so I thought I would write another post explaining how I grow it.  This may not be the best way to grow it, but it is simple and very cheap.  It is really simple to grow watercress.  

Watercress is one of those vegetables which really needs to be eaten soon after harvest.  I never see it for sale in markets, but have been told some places sell it and it will last a day or two in the fridge.  For this reason, if you want to eat it you really should grow it yourself.  

I am told that watercress is a perennial vegetable.  It self seeds so readily for me that even after all these years of growing it I am not yet sure if it is perennial, or if it is an annual and there are always new self seeded plants.  It doesn't really matter if it is perennial or not, once you plant it you can always have some growing if you look after it.  

Watercress

When I tried to look up how other people grow watercress, I found many pictures of people who had sprouted the seeds in an egg shell with a pair of scissors in hand, or people who had ponds or elaborate hydroponic set ups.  This is of no use to someone who wants to grow enough in their backyard to eat (not just an egg shell's worth of sprouts) and/or who lacks a pond or aquaponics set up.  Luckily, watercress really is simple to grow.  

I have grown watercress in several climates, and have found watercress really simple and forgiving.  I tend not to eat it much because I am not overly fond of the taste, so I don't usually grow much of it.  The way I grow it, however, is cheap, and easy, and could easily be ramped up to produce a lot more of it if you were really fond of the taste.  

The first thing to know about watercress, is that it needs soil to survive, not just water.  Like basically any plant you can grow it hydroponically, or using aquaponics, but you can't grow it in a glass of water and expect good results.

The second thing you need to know is watercress needs sunlight (or a grow light).  It will not grow in water without sunlight.  

Watercress needs water, and can grow as an emergent plant with the roots submerged and the leaves in the air, but it copes surprisingly well in soil that is not particularly wet.  Sometimes the seeds fall and plants grow in the lawn among the grasses and weeds.  Not a problem, it doesn't tend to become a weed as it will die in the lawn over summer when it gets too dry for grass to perform well.  As an added bonus, if I ever had a large enough patch of this spring up by itself I can always pull it out and feed it to my chickens.  

Watercress - note the many roots on the stem

Watercress seems to grow better in cooler weather, but does not love frost and thick ice.  It seems to survive being frozen here, but also seems to get a little damaged by frosts.  If I move it under a tree where it in in a frost shadow the water freezes but there is no frost on the leaves and it seems to do fine.

It suffers a little in the heat of summer unless it is given some shade.  Giving some shade in summer also seems to make the leaves grow a little larger.  

The flowers of watercress are similar to any brassica in that they are adored by pollinator insects.  The flowers have a slight fragrance, and are edible.  They smell slightly sweet, and (probably due to all the nectar) taste a little sweet too.  Many people prefer eating the flowers to the leaves. 

Watercress is simple to grow from seed.  The seeds are tiny but simple to germinate, and it takes some time before the plants are large enough to harvest.  Sprinkle some seed on damp soil, keep it watered, make sure it has some sunlight, and it will grow well.  It takes a while for the seedlings to grow, and they are tiny for what feels like a long time, but you end up with a lot of plants. 

Watercress is easier and much faster to grow from cuttings.  Watercress stems grow roots readily when in or near water.  You can cut a stem into short lengths, and either plant them in damp soil, or put the ends in water (with the tops out of the water), and they grow easily.  

There is no trick to this, they don't need a humidity dome, they don't need rooting hormones, often they will all grow.  Sometimes the stems will already have roots before you cut them off.  Once they have some roots, you can just plant them in damp soil and they will grow well.

Watercress seedlings grew in this pot buy themselves

The main issue I have noticed with growing water cress (other than needing to provide water, soil, and light) is cabbage white butterflies.  These will lay eggs on watercress, and the caterpillars will eat out the plants.  I have also had watercress eaten out by water snails, and the plants are sometimes inundated by aphids, but issues with water snails or aphids seem to be intermittent and only strike once or twice per year.  

For me the cabbage white butterflies were the biggest issue.  I am told that cabbage white butterflies are not a big issue, but I found the opposite to be true in my garden for the first few years.  For a while my watercress was growing well only to be eaten to death in a day or two by these caterpillars.  

Then a tiny parasitoid wasp (Pteromalus puparum) appeared in my garden.  This tiny wasp lays eggs into the cabbage white pupa, and eats them out from the inside.  They reduced the numbers of cabbage white butterflies in this area.  While they will never eradicate the cabbage white butterflies, the have lowered the numbers enough for them not to kill off my watercress.  Now the cabbage white butterflies are not a big issue for me.    

You could grow watercress on the side of a pond.  You could grow watercress in hydroponics or aquaponics or even barrelponics.  I am happy to say that you don't need any of this to grow watercress well long term.  It grows well if it is in a pot of soil that is kept moist.  I find it is easier if I grow watercress in soil in something with no drainage.  The bottom of a plastic milk bottle works well.

Watercress, brahmi, and duckpotato

I cut the bottom off a plastic milk bottle, fill it 3/4 with soil, water well, and plant watercress into this.  

As long as the leaves are in the air it grows well, if totallt submerged it will rot and die.  You can plant cuttings which grow faster, or seeds which take longer to reach full size.  

If growing from seed, I make sure that the soil surface is not underwater.  Once the seedlings grow I can fill the milk bottle with water so long as they have some leaves that are not submerged.

The milk bottle in the pictures below was filled with soil and leaf litter that was dug out of the drain in front of our garage.  There is little point buying potting mix, drain soil (or leaf litter cleaned out from the house gutters) is free, and it is full of nutrients.  

Drain soil and leaf litter will have weed seeds, these will germinate, but they won't survive long.  Once the cutting is taller I will fill the container to the top with water, most weeds do not like being under water constantly.  The leaf littler and other stuff in there will break down over time and help feed the watercress over a long time. 

Milk bottle with soil

Watercress cutting with roots

Cutting planted into soil and given water

Once it grows larger I will add more water

It does not take long for the watercress to spread, and for the milk bottle to be brimming with watercress.  I often put azolla and duckweed on the water surface, these act as living mulch and help the tiny ecosystem to be healthier. 

Sometimes I grow watercress in the milk bottle by itself, other times I grow water cress mixed with other water loving things.  Below you can see some brahmi in with the water cress.  There is also a little duck potato in there.  As you can see, the tiny ecosystem is relatively healthy and this milk bottle is productive.

I often just put soil directly into the milk bottle, but you can also put soil in a small pot, and put the pot in the milk bottle.  It doesn't make a lot of difference to how the watercress performs.

Milk bottles don't last forever as they degrade and get brittle in sunlight.  Presumably they are food safe, and if not used for planting things into they would be thrown out.  I have some that have lasted 4 years ad look like they have a few more years left in them, others I have moved often and handled roughly, and they only lasted 2 years.  

These milk bottles were something I already had and were going to be thrown out anyway, so using them to grow watercress, Chinese water chestnuts, and other aquatic edible vegetables is a good thing.   

Growing watercress in a milk bottle

There are a few improved varieties of watercress, but I don't know if any are available in Australia.  All of the varieties I have grown seem much the same and I would not be able to tell them apart if not labelled.  

I once considered breeding an improved variety of watercress, but never got around to starting this breeding project.  This plant is so simple to grow that I don't know if improved varieties are even needed.  I am also not blown away by the taste, so there is little incentive for me to put the effort into improving this already useful and productive vegetable.  

I sell small plants or well rooted cuttings through my for sale page.  I plan to collect seed and also sell seed packets.  You only need one plant to get going, from there you can take cuttings or plant out some seed and expand your patch as much as you want.