We’re generally told to change propagation water every few days to replenish the oxygen (and get rid of that bacterial slime that builds up) but I was curious to find out exactly how often was necessary for two reasons:
- Could I get plants to root faster if I changed the water every day?
- Did I need to change it at all? Or was I wasting my time?
This won’t be a long article, and I hope to update it as I try more intervals, but I do have some results!
The experiment
I took three Rhapidophora tetrasperma cuttings and put them in glass containers (drinking glasses with net pots in them so they didn’t sink). I changed the water of one daily, one y, and one I haven’t changed at all.
Looking back, I should really have taken a fourth that I changed the water every three days, but I have a LOT of cuttings at the moment and I want to wait until they’re all potted up before taking more. The reason I took those three was that the freaking stem had rotted. NEVER MIND.
I actually wouldn’t have chosen Rhaphidophora Tetrasperma at all, because they do NOT like rooting for me in water but they were in the right place at the right time.
I used tap water, straight from the tap. No acclimating or anything.
The prediction
Theoretically, the cuttings that have the water changed more often should root faster. One of the keys to rooting plants quickly is to make sure the node has plenty of oxygen. Oxygen in still water depletes throughout the day, so changing the water every day should cause it root faster.
HOWEVER
I’ve never seen ‘change the water every day to root cuttings faster’ as a tip on any of the many plant care websites/YouTube channels I see. So I assumed that there was a reason that we’re directed to only change it every few days.
The main thing I could see negatively affecting the rooting process was the change in temperature (nodes do NOT like the cold) and possibly the pressure change and general upheaval of changing the water every day could hinter rooting efforts.
I’m clearly just making stuff up here, but you never know!
The results
To all you lazy people out there, I apologise. To all of you people that need cuttings to root quickly, I have some great news.
The two Rhaphidophora Tetrasperma cuttings that I changed the water of weekly or not at all have done nothing. NOTHING.
Yet look at the one I changed the water of every day!
I took the cuttings two weeks ago, and I first saw the start of rooting in about four days. I could just see the end of the aerial root starting to whiten.
The other two cuttings have aerial roots, but there’s nothing on either of them that suggests they’re gonna start rooting:
So we can therefore draw the conclusion that if you want your cutting to root quickly, change the propagation water every day.
HOWEVER
The more eagle-eyed of you may have noticed a flaw in my VERY professional experiment. But, unlike those mascara adverts that are wall-to-wall fake lashes, I’m gonna tell you about the other factor at play:
The problem
Let me just show you a picture of the two cuttings side by side (the weekly one on the right, daily on the left).
The one that rooted is a top cutting. The one that didn’t is a mid-cutting.
Why is this important to rooting?
Well, I’m not 100% sure, which is why I need to repeat the experiment with two mid cuttings. Top cuttings are usually quicker to grow than mid cuttings because they already have an activated growth point. Mid points have to put energy into activating an axillary bud.
The reason I still think that the results of this experiment are somewhat valid is that I have another top cutting of a Rhaphidophora Tetrasperma growing that has been in water for about 6 weeks (possibly more). I’ve changed the water weekly and…nothing. At least, in the roots. The new leaf is growing, though, which seems like a mistake.
Just look at that growth point go!
You may be thinking, yeah, but that looks like a hellish aerial root. And you’d be right…
It’s dried up though. That green on it is algae. It’s also not in the water (it’s in a narrow-necked vase, and I accidentally snapped it trying to get both the stem and the aerial root in the water).
Here’s the node that’s in the water:
Nothing is happening. At all. That white thing is just an axillary bud.
So I don’t think top cuttings are necessarily faster to root than mid-cuttings. They’re just faster to produce new growth.
In conclusion
To be perfectly honest, it’s highly unlikely that I’m going to start changing my propagation water every day. HOWEVER it’s nice to know that in the unlikely circumstance that I need to root a cutting quickly, I can speed up the process by changing the water every day.
Also, I need to try rooting a cutting in nutrient water AND changing the water every day. Maybe I can get cuttings to root overnight, maybe the two factors will cancel each other out.
What practical advice can I give you? Change the water as often as you can – it really seems to make a difference.
