You’ve decided that you are going to take a cutting off of your friend’s plant. Fantastic–it’s one of the greatest ways to expand your garden! But just before you do this, please pause and consider some of the mistakes that I’ve made (and that I hope you can learn from). Avoiding these will give you a better chance of success.
1. Taking too much leaf material.
Plants ‘eat’ by turning sunlight into food, so we need to make sure they have enough leaves. And, besides, more mass will help the plant to be healthier and survive while it builds roots, right? Well, that was my logic at one time and I didn’t realize that my taking too much plant material in a cutting reduced my chances of success. There may be exceptions, but for most plants you want to take one or two nodes and not more.
What’s a node? It’s the place on the stem where the leaf attaches. If it’s a plant where the leaves grow directly across from each other (as with the rosemary pictured), I make a cut one to two inches below the node (if
possible), and about half an inch above it. If one leaf comes off on one side, and another a little way up the stem on the other side I usually take two nodes, making my same cut one to two inches below the bottom node and the other just above the upper node. (I still only take one node if there is a long distance between nodes as with the nasturtium pictured here.
It’s probably not necessary to keep both nodes, but it’s a habit now and I have good success with it.
If the leaves are large, I cut them so that there is just a
small part of the leaf remaining. I only want a few square inches of leaf material for the non-existent roots to support. More than that puts undo stress on the plant.
2. Put the plant in water to start roots.
I grew up watching my mother take cuttings in this way. It really seemed to work. The plants started nice roots in the jar and then I transferred them over to a pot and they usually grew. It’s true that this will often work.
The problem is that plants rooted in this way develop water roots in the water which don’t help them too much in the final growing media. Water roots are notoriously brittle and are not made for terrestrial situations. They often break when the plant is transplanted, and even when they don’t, the plants still have to grow their terrestrial roots once transplanted.
It is much better to root the plant by dipping the bottom cut end into rooting hormone than into soilless mix.
The one advantage of starting the plants rooting in water is that you avoid the plant drying out.
3. Allowing the plant to dry out after planting.
Cuttings need to stay moist. In professional greenhouses they are misted often. I usually cover the cuttings with a clear plastic bag for a couple of days. Before I learned to do this, I often took cuttings and put them in their media and then neglected to water/mist them often enough only to be composting them a day later. (I occasionally still do).
It is a good practice to avoid drying out new cuttings.
Also, the plants can take in some liquid through their leaves, so misting is a great idea since the plant has no other way of drinking.
4. Letting the stem dry out before transplanting it.
After you take a cutting you need to immediately deal with it. If you leave the injured stem for too long it will start to scab over and you won’t get it to root. Rooting from a cutting (on most plants) can only happen where there is an injury. The plant first figures out what type of material it needs to repair (stem, root, leaf, etc.) and then uses appropriate methods to heal. A stem sitting in the air will likely trigger the wrong response and just cover it over with something akin to scar material.
Instead, you need to dip the fresh-cut stem into rooting hormone (to tell the plant that this needs to be repaired as a root) and then plant it before it has time to dry.
5.Cutting the stem straight across instead of at an angle.
Since most plants can only initiate the root growth from an injury, you want to make a relatively large injury. The best way to do this is to cut the stem at an angle so that there is a large area from which to root.
I had rooted plants for years thinking that I wanted to minimize the damage to the plant and so I did exactly the worst possible thing by cutting neatly, perpendicularly to the stem. I’m sure that my success would have been exponentially better if I had cut them at an angle and used rooting hormone to boot.
I made many mistakes when I started learning to take cuttings. Some, like putting cuttings in water and not using rooting hormone, I learned from people who taught me to do it that way (and it does sort-of work). But many others, like cutting the stem straight across, letting the plant dry out before or after transplanting, and taking too much plant material came from a poor understanding of plant physiology. As I have learned more about how plants work, I’ve abandoned some bad habits and I thought I’d share those here so that you can also learn from my mistakes.