Monday, 10 February 2014

Growing Water Chestnuts in Buckets

The water chestnut (Eleocharis dulcis) is a type of sedge that is found growing in tropical wetlands of the world.  They are simple to grow, highly productive, and nutritious.  As well as providing food for you, they yield a decent amount of straw as well as providing habitat for frogs and water insects, all in all they are an excellent permaculture vegetable.

I always wanted to grow water chestnuts, but was never able to find any to plant.  People often comment that they are cheap to buy from supermarkets so they are not worth growing, but I have never seen them for sale except in cans.  I have no idea what chemicals are used on the water chestnuts that I do buy in a can.  I do not know where they grow, how far they have traveled to reach me, how they are grown, or anything like that so growing my own water chestnuts organically seems like a sensible approach.

I have heard of a lot of different ways to grow water chestnuts, and I have heard a lot of people complain that they tried to grow them and failed miserably.  So I thought I would write a post about how I grow them, this is not necessarily the best way, but it works for me and requires very little time and effort.
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Water chestnuts growing in buckets

How I grow water chestnuts

The first mistake people make is rotting the dormant water chestnut corms.  I plant the corms in a small pot or punnet and keep it reasonably damp until they sprout.  I used 10cm square pots that we had in the shed, I put the cheapest potting mix in and planted the corms so that they were not quite touching each other.  I do not make it any more damp than I would if I were germinating tomato seeds.  If you put the corms under water prior to them sprouting I believe that they will mostly rot and die.  I planted them in late winter/early spring and kept them away from frost.

I then watered like I would any seedling until they were about 5cm tall.  At this stage I put the pot in an ice cream container and filled water half way up the pot, a few days later I put water up to the top of the pot so that the soil level was at the water level.  I then left the water level there for a few weeks.  This gives the water chestnut a chance to grow roots and the leaves start to collect energy for the plant ready for the next step.

People make a few mistakes in the nest step, they make the water too deep and they do not use enough soil.  Water chestnuts grow in soil, that is where they produce their crop, so if there is not enough soil then they will produce a small crop or a crop of very small corms.  They are an emergent plant, which means that while the roots are below water, the top of the plant must be in the air otherwise they will die.  I then separate the corms and plant them in soil which had about 10cm of water on top of it.  In this way the little plants were just under the surface of the water and would grow out of the water in a few days.  You can make the water deeper, but not too deep, up to about 30cm should not harm the plants but any deeper than this and they may struggle.

In a perfect world they never experience any frost, unfortunately mine seem to see a few light frosts when they are young.  I try to make sure the frost they see is not too hard and they seem to do fine with it.  Interestingly they handled a light frost better than duck potatoes.  They even had some ice on top of the water a few times, while it is less than ideal they are hardy enough to cope with that.

The water chestnuts then grow during the warm weather and die down in autumn.  When they die down the water level is dropped and the corms are left to dry a bit in the soil.  When they have dried down a bit they are dug up and eaten or stored.  If they are ever completely dry they will die.

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Water chestnuts growing in the shade of a plum tree

Where I grow water chestnuts

Ideally you would grow water chestnuts on the edge of a pond or slow flowing stream.  In a perfect world they would colonise this water edge and all you would do is go and collect them.  Many people, including myself, do not have access to a pond or stream so this method is unachievable.  

Many people who do not have access to a pond grow them in a bathtub, while this method sounds great it takes up space and you have to be able to find a free bathtub.  Finding free things where I live is almost impossible so I had to think of another way.  I have heard of people growing them in an icecream container filled with soil and submerged in a fish pond, they say they yield about 30 corms per container.  Again this sounds great but requires a fish pond which I do not have.

People often tell of growing them in styrofoam broccoli boxes that they get for free from the fruit and veg shop, out here we can not buy styrofoam boxes let alone convince a shop owner to give them away so I had to keep thinking.  

There are a lot of plastic tubs and boxes that I have seen used, but they all cost too much, I want to produce high quality food for cheap.

I found some cheap buckets for sale, buckets hold water, they look ok, they are easy to find in pretty much every town, they are large enough for one corm each, and they do not take up too much space.  If you only had a balcony this method would still work.  So I decided that buckets would be the containers I would use in which to grow water chestnuts.

I then dug up some subsoil clay, mixed it with animal manure, put it in the buckets to about 5cm from the top, and filled with water.  The soil settles a bit over the next little while so you end up with more water above the soil level.  

It is important to leave it for a few weeks because if you planted directly into this the water chestnuts would rot.  Any weed seeds germinate in the wet soil, the weeds can not survive being constantly under water so they die off reasonably quickly and pose no problems.  Over the next few weeks the water goes green, then crystal clear, then green a few times as algal blooms deal with excess nutrients.  This is good, do not worry when this happens as this is what you want.  The water seems to do this on and off throughout the entire growing season, again do not worry as this is normal.

People are often afraid of clay or subsoil, but they hold a lot of minerals.  Being underwater it makes the soil soft enough for plant roots to penetrate and renders these minerals available to the growing plants.  The only thing to watch for is that no rocks are in the mix.
Growing water chestnuts in buckets
Water chestnuts growing in a bucket with duckweed

Once the water has had a few weeks to work itself out I then plant the water chestnuts in the fertile mud.  They were not tall enough to reach the air yet, but that is ok.  By now they should be strong enough to grow a bit to reach out of the water.  I also put a bit of duckweed floating on the water surface.  The duckweed grows to cover the water surface and blocks light from the algae.  It also slows evaporation, cools the soil by providing shade and helps out in a bunch of other ways.  If you have access to azolla I would include that too as it fixes nitrogen from the soil and fertilises your water chestnuts.

As the water chestnuts grow to fill the bucket they send out rhizomes, I had a spare bucket of mud so broke off one of these rhizomes and planted it.  It did not take long before it grew so much that I could not tell which bucket had a corm planted and which one was from the rhizome.  From here I simply kept the water at the top of the bucket by filling it up each afternoon when watering other vegetables.

Everywhere you read and everyone you talk to will say that you must grow water chestnuts in direct sun and avoid shade at all costs.  At first this is what I did and it went well for me, but then summer came along and it got too hot.  Even though there was still water in the buckets the plants were suffering from the relentless heat.  Being in buckets made it simple to move the water chestnuts under the shade of a tree.  I moved 2 buckets at first to see if that helped, those plants started growing again while the ones in direct sun were still going poorly.  Now I grow all the water chestnuts under part shade, they seem to be growing fine there.

How I harvest water chestnuts

When the time is right the foliage of the water chestnuts starts to yellow off.  This is a signal to stop watering the buckets.  When they have dried off for a while you then dig through and collect the water chestnuts.  It is important not to let the corms freeze if you are planning on replanting them the next year as freezing will kill them.  If you plan on eating them freezing is fine.

I wrote another post here about the yield I got from a bucket of water chestnuts.

Where to find Water Chestnuts for sale in Australia

I sell water chestnuts for planting and growing on my For Sale page. As you can see above they are simple to grow and very productive.  Chinese water chestnuts are a great perennial vegetable and fit in well in a permaculture vegetable garden.


  1. Hi if you're keeping the corms to plant next year how do you store then? Thanks

    1. Hi Loch,

      I wrote a blog post on just that topic last year:

      I used to dig them up and carefully store them, now I often just store them in damp soil and don't put much thought into it. They are surprisingly hardy, I have been growing them continuously for a few years now and they have never been too difficult to grow or store, and they are very productive.