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Growing plants in water can be a really cheap, easy, and unique way to create a bit of home decor using a cheap plant and a vase.
In fact, I've developed a bit of a weird habit for buying random condiments at the supermarket especially for their bottle (it's WAY cheaper than buying vases, plus you get to try stuff you wouldn't otherwise).
There is no *correct* way of keeping houseplants.
Houseplants can thrive in a variety of media, and if you like keeping plants in water, leca, perlite, or soil, GREAT.
The easier you find plant care, the more enjoyable it’ll be, and the less likely you will be to neglect them.
I find keeping plants in water culture pretty easy BUT I only have my Thai Constellation and my Syngonium Tri-leaf Wonder in water atm. Changing the water of one vase is FINE (I use oxygenating java moss with my Thai so I don't need to change the water that often) but I cba to change the water of a dozen plants every week. Also, when things go wrong - side-eyeing my stinky Monstera - I only have one plant to navigate. I don't know why the water is suddenly smelling like drains all of a sudden, but I'll get to the bottom of it!
So yeah, keeping plants hydroponically is great, but experiment with one plant first.
Do Syngonium/Arrowhead like living in water?
Syngoniums do really well kept in water.
I had a major thrips infestation a few months ago that nigh-on killed my Syngonium Tri-leaf Wonder. I rehabbed it in the aquarium but it didn’t really do much so I put in a vase in my south-facing window to see if it would recover. It did! It’s started growing really well, and the roots are looking good.
The only issue is algae. It’s not harmful – it could even be helping, since algae produce oxygen (Note to Editing Caroline: this phrase reads weird, but it’s because algae is plural, hence produce not produces) – but it doesn’t look great.
This is another reason I don’t keep plants in water much – the algae. It can look super cute, but requires a lot of washing of vases which is NOT something I’d remember to do.
How to switch a Syngonium from soil to water?
The quick version is that you simply need to clean all the soil off the roots and put it in a vase of water.
Sometimes it’s that simple – some Syngoniums have roots that soil can’t really adhere to. You can rinse them off under the tap and be good to go.
Other times, Syngonium roots are incredibly thin and covered in soil that you can NOT remove.
It seems to vary, and is different for every plant, even if they’re of the same species.
The good news is that Syngonium roots are pretty tough, and as long as you keep the water well oxygenated, root rot is pretty rare (in my experience, anyway. I've transitioned a lot of Syngoniums to leca and never lost one).
The bad news is that, well, your cute piece of decor's gonna look a bit manky and grim until all the soil soaks off. Over time, lovely clean water roots will grow in, so it's not gonna be forever. Except over time they'll go green with algae (again, no problem for the plant).
I’m not trying to put you off keeping plants in water, I just want to prepare you for all the algae ESPECIALLY since the better the light, the more the algae.
Of course, you could always take a cutting of your Syngonium, put it in water to root and just…leave it.
If after a few months (or years) you can always transition back to soil.
How to care for Syngoniums living in water
One of the benefits of keeping plants in water is that overwatering isn’t a thing. The only similar issue you’ll have is lack of oxygen.
That means that if you’re the kind of person that has a busy life and can only fit in an allotted hour of plant care per week, plants in water are perfect.
Change the water and you’re done.
If you travel a lot and want to reduce your workload further, then you can add a bubbler or even some oxygenating water plants to your vase.
Syngoniums are often recommended as a great low-light plant, and they can be BUT I’ve noticed that they don’t grow very well in lower light when they’re in water.
When mine was in the aquarium, it grew…ok but not as well as it does now. There was light on it, but not that much, since it was a tank with skittish fish that prefer lower light.
They do ok in lower light, so if that’s all you have, still give it a go, but I didn’t get significant growth until I put them right in the window.
Changing the water
As I discovered when conducting experiments for this article, the more often you can change the water, the better. However, if your plant has decent roots – i.e. look something like this:
Then you can just dump out and replace the water weekly.
If you add oxygenating plants or a bubbler then you can get away with changing it WAY less often. I change the water of my Thai Constellation every six months, and it’s totally fine and growing well, but I think we can all agree that that’s probably not quite often enough.
I would say every month/six weeks is probably optimal.
The first thing you need to do is make sure you’re using a fertiliser that’s suitable for hydroponics. I use the General Hydroponics Flora Series, but there are loads on the market. I don’t think there’s that much difference between them tbh, so find one that fits your budget.
Soil contains certain micronutrients, so soil fertilisers tend to list their N-P-K ratios, but little else. There will be micronutrients in there, but they rarely list the specifics.
Hydroponics fertilisers provide the full spectrum of micro and macronutrients since often people growing plants hydroponically use RO water that contains very, very few (if any) trace minerals.
I usually switch out my water for nutrient water every month. So one week of the month, my Syngonium sits in nutrient water. Then the following week, I dump it out (usually onto one of the plants in my garden) and replace it with plain water again.
What water should I use?
I use tap water. My tap water is ok (pretty hard though) and I don’t measure the pH (should I? Probably).
My general rule of thumb is that if you’re happy to drink the tap water, it’s probably fine for your Syngonium. I use tap water on ALL my plants, but if I see issues (for example on picky ones like Calathea) I switch to aquarium water, which is tap water with dechlorinator in).
If you want to use distilled or filtered water, go ahead. I use tap because, er, it’s easiest.
I fill the vase straight from tap, and plonk the Syngonium straight back in. In winter I might add a bit of warm water in (just so it’s tepid, not actually warm), or get my boyfriend to fill it with aquarium water when he’s doing a water change.
Can I put a Syngonium in a fish tank?
As I detailed in this article, you can keep most tropical plants in aquariums if you can keep their leaves out of the water.
The easiest way to do this is to take a cutting of your Syngonium, and leave it to callus overnight. I don’t really think leaving plants to callus does anything for the plant BUT we don’t want sap leaking into the aquarium if we can help it.
Then just leave your Syngonium to grow. The most difficult thing is keeping it upright and out of the water. You can get little pots that stick to the side, or float a slide of pool noodle and sit your cutting in it.
How to support a Syngonium in water
I’m currently just planning to let mine trail. It’s a ballache getting plants to grow up when they’re in water. With my Thai, I’ve poked the aerial roots back into the jar and that keeps her upright but Monster have much longer, thicker roots than Syngonium.
You could always try a Kratiste pole. They’re extremely lightweight, so you could tape one to the side of your vase (you’d have to use one with straight sides). The aerial roots attach by themselves so you wouldn’t need to worry about attaching it.
The only issue would be dumping out the water - a 90cm pole attached to a vase can make it trickier to tip water down a sink (this sounds ridiculous, but it can be a pain if you only have a small sink in an inconvenient space).
If you want to try keeping a plant in water, Syngoniums are an awesome one to try. They’re low-effort and adapt well, but they don’t grow as big and unwieldy as Monstera.