I haven't posted in this section in a long time, but I think I can contibute...I've rooted a number of hoya this way. In my experience the root will only come from the node of the plant, and I've had the most luck when the node is just touching the soil. I usually leave a portion of the internode intact for support, to keep the cutting upright in the (barely moist) soil.

At least as important to success is keeping humidity high around the cutting until it develops roots. With hormone alone I only get about 50% of my cuttings to root, but if I stick the pot into a sealed ziplock bag, success is much closer to 100%.

Tyler

Node. Or internode. That is the question...

Thanks, Tyler. Your vote is clearly for the node.

J.

Depends on the plant. Begonias will root without a node, as will coleus (Solenostemon), Plectranthus, Hedera, Saintpaulia, Peperomia, Alternanthera dentata, Hoya, Cissus, Pilea, Ardisia, and several others. Even in the cases where a node is not strictly necessary, it doesn't hurt to have one.

Pothos (Epipremnum aureum) does require a node, as do Tradescantia, Philodendron, Cordyline, Yucca?, Aglaonema, Dieffenbachia, Syngonium, etc.

I'm not personally convinced that rooting hormone is all that useful, but I think it's fairly rare for it to slow things down, too, so use it if you like.

I'll share a trick abt Rooting Hormone which I learned from the Orchid Growers. As many people do, I use Rooting Homone (RH) more for the antifungal properties than the RH aspects. I learned that cinnamon is a good antifungal & can be used in the same way. Dabbed on the bottom of the stem w/ a small brush, shake off the excess & plant (then I don't water in, maybe just the lightest spray on the mix instead).

I'm not sure if this is anyone else's experience but for me, it seems like rooting hormone causes roots to form more quickly, but isn't essential for getting them to form in most cases.

amcour wrote: "I'm not sure if this is anyone else's experience but for me, it seems like rooting hormone causes roots to form more quickly, but isn't essential for getting them to form in most cases."

Some plants are amazing, and will even readily form roots from a leaf that is in contact with moist soil for a while. Others seem more reluctant to form roots, stubborn even.

With heartleaf philodendron, I notice that the nodes are sometimes forming the beginings of rootlets even when they're hanging in the air. So the nodes are obviously prone to root formation.

In the case of my current heartleaf p. plant - which is very lush and vigorous - I've found myself cutting the ends off of the vines every few weeks because of the growth rate of the vines. For esthetic reasons, I've mainly been cutting the internodes just below a node (because this leaves a pretty little leaf at the end of the trimmed vine). And I wanted to figure out if I could then plant the internode down into soil, having dipped the end into rooting hormone.

In the past, though, I have cut off some nodes along with a piece of internode, and I've stuffed the node into the soil with the bit of internode (and possibly a young, small leaf too) protruding up into the air. These have often taken root.

Sometimes I've dipped the node into the rooting hormone too, before planting it in soil, just for good measure.

But I wasn't sure how an internode without a node would do, even if given rooting hormone.

Joel

Mr. Subjunctive wrote: "Pothos (Epipremnum aureum) does require a node, as do Tradescantia, Philodendron, Cordyline, Yucca?, Aglaonema, Dieffenbachia, Syngonium, etc.

"I'm not personally convinced that rooting hormone is all that useful, but I think it's fairly rare for it to slow things down, too, so use it if you like."

Then I take it that with the node of the vine (say, heartleaf philodendron) it is not simply the natural presence of a concentration of indole butyric acid that causes the formation of roots, once the tissue is in contact with moist growing medium?

My question comes from a possible misconception of mine: I was thinking that possibly when I.B.A. came into contact with living plant tissue, as in vine internodes, it would tend to generate rootlets that would then be encouraged to grow in a growing medium (i.e., "soil"). In other words, I though maybe the internode would then act like a node. But I believe you are saying this isn't the case, correct?

J.

Well, it might be that the roots form on a Philodendron vine because there's a local concentration of IBA, but it could also be that Philodendrons don't use IBA at all and just automatically try to grow aerial roots at every node. I don't know specifically what's going on in the plant.

I am fairly certain, though, that you won't be able to trick the plant into thinking that an internode is a node, because I've never seen roots forming anywhere other than at a node on Philodendrons, or on any other genera in its family. Not that it hurts to try anyway, especially not if you have a new batch of cuttings every few weeks to experiment with. But I would be surprised.

With rooting hormone I believe it is possible to root most cuttings without a node, but if that cutting would naturally (ie: without hormone) require a node for propagation you are unlikely to get any top growth. I tried rooting a philodendron once about four years ago without a node. It produced roots, but I didn't get any new leaves. It could be that I just didn't wait long enough, but three months after developing roots the plant still didn't have any new leaves. I tossed it at that point.

Tyler

Anyone know the science on indole butyric acid (IBA)? I thought it had been identified as THE natural rooting-trigger chemical among plants. And that the synthesized version of it is the same molecule as that forms within plants.

Second question (assuming the above is correct): is IBA used within the pragmatic professional nursery & general horticultural field? Or are the gels and powders only promoted to amateur customers at "garden stores"?

One thing I'll say from experience is that the gel does seem to adhere well to cuttings. I've noticed this even after I've inserted a cutting into growing medium and then pulled it up to inspect it a day or so later (simply because I was wondering if the gel did or didn't adhere, not to look for rootlets that soon).

Joel

I think other rooting hormones exist, in certain species, though IBA is the most common.

The synthesized version is identical to the natural (though with the caveat that there could be other chemicals in plants that work to amplify or mute the signal, and as pirate girl alluded to upthread, some commercial rooting hormones also have an antifungal in them. So the IBA is the same, but what comes with it could be different. How much difference does this make? I do not know.).

As for whether this is actually used in professional settings, I can only answer regarding the place where I work: we do use rooting hormone sometimes, though not in a particularly consistent or rational manner. I'm using some right now to take some geranium cuttings, but if I remember right, we didn't use any on the geranium cuttings we took in the spring. It probably does make a difference in some cases, either for good or ill, but the opportunity doesn't come up a lot to test the effects, since there are generally eighty other things going on at any given time.

I don't use it at home at all, ever.

Well, here is the result of a little experiment using cuttings from heartleaf philodendron. I'll note here that is is not "good" science, because among other things the number of cuttings was small. But it is suggestive....

I tried rooting four cuttings, each with only one smallish leaf. Two cuttings were each just a leaf on an internode section (vine, but no node), and two were a leaf, short bit of internode, and a node. I used a gel form of IBA-plus-fungicide. I cut the pieces with a sharp clean knife, and immediately dipped either the node or the end of the internode into the gel, then put it into a shallow "hole" in the growing medium in the pot where my other heartleaf philly vines are growing wonderfully. I then packed the soil in snugly around the base of each cutting. I made sure the area where these new cuttings had been inserted stayed moist, while avoiding drowning of the cutting ends by overwatering. I waited two weeks.

Three of the cuttings dried out and pretty well died (i.e., bottom portions turned coppery colored, then shrivelled and dried out). One - with a node - took root nicely. On pulling out the three dead cuttings, it turned out that one of the two internode cuttings had indeed grown a few root hairs - but apparently not fast enough to bring sufficient water into the cutting and prevent its demise.

This little informal experiment suggests to me that internode cuttings treated with IBA can develop root hairs. But possibly cuttings without IBA treatment would have done just as well (?). It also suggests that a cutting WITH a node has a better chance of rooting.

As I mentioned, this was simply an easy-to-do informal trial, and was good for stimulating a bit of reflection. I welcome anybody who has experimented more extensively with IBA or vine cuttings (or anything related) to post here about what they've observed.

Happy houseplant growing.....

Joel

you just stick the cut ends (with 1 leaf) into soil. No hormone. They root easily. You can even root them in water and leave them there if you like.