Kangkong - perennial vegetable from South East Asia

A number of years ago I heard of a perennial leaf vegetable called kangkong (Ipomoea aquatica and/or Ipomoea reptans) that is not very common here but is extremely popular in south east Asia. 

It has heaps of common names including ong choy, Chinese spinach, Chinese watercress, Chinese convolvulus, swamp cabbage, water spinach, river spinach, water morning glory, and water convolvulus.  I am sure kangkong has a lot of other names too.

Kangkong was reputed to be fast growing (~10cm per day), high yielding, undemanding to grow, and tastes good.  Kangkong is absurdly healthy to eat, it is high in many vitamins, high in various minerals such as iron, high in essential amino acids, and has reasonable amounts of fiber.  It also has few calories and almost not fat.  Kang kong is said to reduce cholesterol and has blood sugar stabilising effects (which I need).  To me kangkong sounded intriguing and well worth trying.

Kangkong was said to grow in water and do very well in aquaponics.  I keep hearing how this is sold in bunches at the markets and that it is simple to grow from cuttings, but have never actually seen it for sale in a market anywhere.  

I occasionally see kangkong plants for sale online, but not very often.  So I tracked down some seed and grew some myself.  Back then kangkong seed was difficult to find anywhere, so I think I was lucky to be able to get it.

Kangkong

The seedlings produced rather distinctive forked cotyledons as they germinated, and seemed to germinate in soil better than they did in water.  The ones in water rotted, the ones in soil all germinated quickly for me.

I have since heard that kang kong is very difficult to germinate, but I didn’t do anything overly special and they germinated just fine for me.  The pot below I planted five seeds and had five seedlings germinate.  Maybe I was just lucky.

Kangkong seedlings germinating

Kangkong leaves and spent flowers

My kangkong seedlings grew reasonably slow at the start and after germination seemed to sit there doing nothing for some time, eventually they got large enough to eat a little.  It felt like they took a long time to reach a reasonable size, after that they grew very fast.  I grew most of them crowded in small pots of soil, where they did surprisingly well.  

I thought that kangkong didn't taste very strong, it certainly never tasted bitter.  To me kangkong was good raw or cooked briefly in a stir fry.  My kids happily ate raw kangkong leaves that they picked as they walked in the garden.  The fact that my kids would graze on this says a lot about it.  Our chickens and guinea pigs also liked to eat kangkong leaves and stems. 

I also grew one kang kong plant in a floating pot in a classroom aquarium, this plant did extremely well.  From what I have seen kangkong is well suited to aquaponics.  I have read a few academic papers that demonstrated that kangkong is vastly superior in reducing nitrates and phosphates in water than fast growing brassicas.  It seems to have potential in cleansing water and for soil stability in wet tropical areas.

I doubt I grew my kangkong properly.  I gave them next to no attention, they were crwded in a tiny pot of soil, and they were not in very fertile soil, but they still produced a reasonable amount of leaves pretty much constantly over the warmer months.  Some flowered towards the end of the season, but I never saw any sign of them producing seed pods.  This lack of seed setting may be due to my short growing season, but I have a feeling it may have been due to the lack of attention that I paid them and the poor growing conditions.  The pots were far too small, the soil too poor, and they did not get enough sunlight. 

Like many other vegetables that we commonly grow, kangkong are tropical perennial plants that do great over summer and tend to die over winter in cooler climates.  I didn’t want to grow from seed so I protected some plants over winter by keeping them out of the frosts.  They suffered badly through winter, but they survived.  Temperatures below 12C made them lose leaves and die back to depressing little stumps.  Any frost killed the plants completely, but keeping a pot of kangkong out of the frost was simple enough to do.

Kangkong struggles over winter

Once spring came I had a pot of sad little stumps with no leaves and a lot of dead bits, I doubted that these would recover so I also planted some more seed.  These sad little stumps took off and flourished as soon as the weather warmed, and considerably out grew any seeds I planted that spring.  

There was no comparison in growth rates, the overwintered plants were larger and produced far more leaves earlier in the season.  Again they flowered but did not set seed, I never cared about seed from them as I still had some seed in my packet, plus they are true perennials that were simple enough to get through winter in that climate.  In hind sight I regret not valuing these vegetables enough.   

Even though my climate was not ideal for them, I grew the same kangkong plants for a number of years then moved house and brought some of my plants with me, they kept producing leaves for me to eat which I really appreciated.  At the time due to work I was living away from home during the week, and coming back on weekends where I would eat handfuls of the stuff.  

As I had my garden in pots of soil sitting on concrete, kangkong was one of the few things that produced anything edible for me over this time.  Having a few hand fulls of kangkong as well as Vietnamese coriander, really helped me during this time as I was producing nothing else edible at the time.

A few months later I moved house again.  I don’t remember what happened to my kang kong because I had a lot  going on during that time, but I somehow lost them all, and I haven’t grown any kangkong since. 

Kangkong growing in a 10cm pot (in an ice cream container) and flowering

It has been a few years since I last grew this, but I keep thinking of growing kangkong again.  It was so simple to grow, was so productive, very undemanding, kangkong is meant to be really healthy, and it actually tasted alright.  Much like many other great vegetables I can’t buy this in the markets, meaning if I want to eat it I have to grow it myself. 

I found some of my very old seed (from 2013) and have planted some to see if any germinates for me.  I also bought some new seed just in case the old ones are no longer viable and have planted some of that.  I didn't know if they can germinate with the temperatures so low, so I planted them with bottom heat.  Some are already germinating.  I didn't plant much of the seed, I will plant more in spring if these sprout and die off due to the cold or something.  

Kang kong flower bud

Last time I grew some kangkong in soil as well as some in a floating pot of gravel in a fish tank.  This time I will try the soil again, but I would also like to grow some using aquaponics as I think that is the only way for it to reach its potential in my climate.  I have heard of it exploding in growth in aquaponics and being too productive - that's what I want!

The floating pot of gravel performed incredibly well last time, but I have plans to pump aquarium water through a bed of gravel and I think kangkong may do even better in a set up like that.  I am kind of excited to see what kang kong can do in my goldfish barrelponics as I think kangkong may be perfectly suited to that kind of growing.  Being outside in full sun, having constant access to a stream of nutrient rich water, it should really take off over summer. 

I enjoy vegetable breeding and (as well as many failures) I have produced some incredible plants.  A large part of me wants to buy seeds of as many different varieties of kangkong as I can find, cross them all, and see if I can produce a superior variety.  Being a perennial means that if I do stumble upon an exceptional plant I don’t have to breed it for generations to stabilize the superior traits, I can simply take cuttings and clone the thing.  

Another part of me does not want to do this as regular kangkong is already pretty great, I have no experience in collecting kangkong seed, I don’t have a lot of space or water to use on yet another vegetable breeding project, and this sounds like a lot of work.  I guess time will tell, it sounds like something I will eventually do but I may not invest a lot of effort into it just yet.

Kangkong flowering - this plant needed more nitrogen and more sun

I will probably sell kangkong through my for sale page at some stage in summer.  I am interested in getting a few more kangkong varieties and would love to track down the red stemmed kangkong.  If you have some red kang kong in Australia and are willing to sell or trade it let me know.  Or if you are overseas and are willing to post me some seed of red kangkong I would also love to hear from you.