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First things first – there are a TONNE of factors that can influence how fast a cutting roots, so your results might be different from mine. With this in mind, I thought I’d start this experiment in February.
I used Philodendron brasil for a couple of reasons:
- It roots fairly readily
- I have a big enough plant to take ten cuttings. Also, I can pot them all back up together with the main plant and grow a super bushy one
By starting myself off at a disadvantage with both light and temperature, I thought it would really help to negate factors like plant health. There are a couple of methods that I did for fun but aren’t easy to replicate (for we don’t all own aquariums and terrariums).
I changed the water twice a week (usually Wednesday and Saturday) for the first few weeks, and then weeklyish (or less once roots were developed).
I started in February, and we’re now in early April. In warm weather it would be quicker, but I thought I’d do it in winter because…that’s when I had the idea to do this.
I’ll explain the different methods I used, what worked, what didn’t, and why.
What propagation methods did I test?
I tested out ten different propagagation methods:
- Plain water
- Water with Superthrive (1ml per 250ml water)
- Water with fertiliser (I used the General Hydroponics Flora series – 1ml of each in 250ml of water)
- Soil with fertiliser
- Soil with rooting hormone
- Terrarium (in soil)
Which propagation method roots fastest?
Superthrive produced growth first, but it quickly became apparent that water with nutrients in is far and away the fastest way to root cuttings.
Like, no contest.
In fact, the one with Superthrive TO THIS DAY has zero roots and a little growth point. Like, it did something, but not the right thing.
And the one with nutrient water, for comparison:
There is something interesting about the nutrient water propagation – the new roots came out of the ends of the aerial roots. As far I can tell, all of the other propagation methods had the roots emerge directly from the nodes.
Those first roots came in about two and a half weeks. I took the cuttings on the 31st of January, and I got roots on the 17th Feb:
Also, for the sake of transparency, I gave up on measuring out the nutrients and just eyeballed it (by tipping in as little as I could – into the lid, just in case).
If it looked a bit dark, I’d add more water.
You might be thinking, well yeah, the one on the right doesn’t have any aerial roots, but it does. they’re just round the back. I tried to make the cuttings as similar as possible in terms of number of leaves, nodes, aerial roots etc.
I can only think that something in the nutrient water activates the mechanism in the aerial roots that turns them subterranean roots.
How did each of the other propagation methods do?
I took this photo on the 11th April, so 70 days.
I mean, fine, but a little underwhelming. To be perfectly honest, when you consider the ballache of having to add the nutrient water, this would probably be the easiest method.
I’m planning to do an experiment on how changing the water more frequently impacts the speed of root growth, just to see.
There’s no point in changing the water twice a week when a once a month will do! Or, why wait a month for roots when you can get them quicker if you change the water every day.
The issue here isn’t the medium itself (I don’t think) but the act of taking it out and putting it back. It kept falling out and I didn’t notice so the node wasn’t consistently moist. That being said, it worked FINE so if you’re the type of person that can’t be relied upon to change the water regularly, then this method is for you.
Still 70 days for this much growth is…not the one.
I recommend keeping the water level just below the cutting if you’re not planning on changing the water. If you change the water frequently, then keep the node under water.
You may be wondering why you’d bother with leca at all if you’re going to keep changing the water, but it’s actually a great way to root multiple cuttings in one glass and keeping them all from falling in the water.
Leca + nutrient water is definitely worth trying, and on my list of things to try.
Moss, soil (plus additives)
So this encompasses moss, soil, soil plus hormone, soil plus fertiliser.
None of them are rooted AT ALL. It’s now APRIL. So, like two months.
This is interesting, because rooting in moss is the darling of the house plant world, and I got NOTHING.
I was so good at keeping it damp too!
I think the issue was definitely temperature. There was mould on top of the soil and moss which is fine, but can be a sign that it’s a bit too cold and the humidity is too high.
I’m not wasting four cuttings so they’re all in nutrient water atm.
Isn’t it weird? It’s so long and skinny – it makes me feel uncomfortable.
This one took AGES to root, and I think that’s purely down to the lack of light. The aquarium lights are only on for a few hours at the moment and the window was blocked by thermal paper. I think this one only took off once the window was unblocked.
This is another SUPER easy one though, because you don’t need to change the water. It’s my boyfriend’s aquarium, so I don’t need to do any maintenance. The only thing stopping me from filling it with cuttings is that…he doesn’t really want me to. And considering our entire house is full of plants, it’s only fair that I don’t invade (too much) 200 litres of the house that are for his hobbies.
Top marks. Great roots, and the humidity in the terrarium means you don’t have to water, you just need to thoroughtly damp (and then squeeze out) the moss or soil first. I used soil with moss in it, because it’s easier to acclimate back to soil.
I’m going to explain later on why speedy root growth isn’t necessarily a sign of a quick propagation, but this is a classic sign of it.
In the beginning, I was checking the roots frequently, and this one rooted quite late compared to the ones in water. I don’t know exactly when it rooted, because I think being yanked out frequently was hindering root growth. It’s definitely the most established root system – the roots are longer and thicker than those in the nutrient solution.
The roots will form much more slowly in soil than in water, but once they get going, they grow quickly. The best thing about the terrarium is that you can literally stick the pot in the terrarium, and it should stay moist due to the humidity.
What else can I add to make cuttings root faster?
The key things are to increase:
- Oxygen to the node
Why fast rooting is not the be all and end all
This is something I learned early on in my propagation journey (hate that phrase; can’t think of a better one):
fasting rooting does not equal fast growth
I’ve had plants roots suuuper quickly but then do NOTHING. FOR MONTHS.
To illustrate my point, here’s a photo of the cutting I rooted in nutrient water:
It’s fine! We didn’t lose the original leaf (always a bonus, never a guarantee), and we have new leaf. This new leaf was on the cutting when I cut it, and it seems like it’s going to be ok. Most of the time, undeveloped leaves on propagations don’t make it.
So it’s doing well.
But then look at the cutting in the terrarium:
Not only does it have a more established root system, but it has new growth unfurling AND aerial roots that are ready to climb.
Fasting rooting is not always a guarantee of fast growth.
I tried to keep all of these cuttings of a similar size so I could compare them more easily, but in general I’ve found that plants with more leaves root more slowly but then put out new growth faster.
However, more leaves = bigger cutting so there’s more risk if it fails. If you root individial nodes you’re more likely to have at least one successful cutting.
As you get more used to propagating, and you find a method that works for you, you can experiment with the size of cuttings, but I recommend beginners start with single of double leaf cuttings.
The thing I’m most proud of is sticking to changing out the water every few days. I don’t usually stick at thing for long, but a load of my plants look a bit scraggly, and the easiest/cheapest way to grow them bushier to chop and rop, spo here we go.
Nutrient water was the fastest way to root, so if you’re propagating something that you’re anxious to root quickly, nutrient water is the way to go. If you have a terrarium, you could always try putting the vessel in the terrarium (I didn’t do this, because all the isopods would drown, and i don’t want to risk them, or the frog/geckos).