Cuttings 101

With cuttings, a plant stem becomes a whole new plant in just a few weeks! Ill.: Maria Flaya, depositphotos

By Larry Hodgson

Taking cuttings of plants is far from being a new technique. Ever since plants have existed, most have been able to reproduce, at least occasionally, through cuttings. When a branch falls to the ground and conditions are right, it produces roots and a new plant is born. And the good news is that the results are even better when you don’t leave things entirely to Mother Nature, but start the cuttings purposefully. Plus, taking cuttings at home isn’t even difficult. . . if you know how to go about it.

What to Cut?

Several parts of a plant can be used to produce cuttings.

Some plants (especially weeds such as quackgrass and Japanese knotweed) have the ability to regrow from a section of root or rhizome placed or left in the ground (this is called a root cutting). Still, the ability to sprout from root cuttings remains relatively rare.

The same goes for leaf cuttings, where you grow an entire new plant from a single leaf. This is only possible with very few plants, such as African violets, crassulas and sansevieras.

On the other hand, stem cuttings, where you root a section of the plant’s stem, are possible with almost any plant that produces stems: houseplants, shrubs, trees, perennials, conifers, climbers and many more.

Let’s focus here on taking stem cuttings of houseplants, as these are the most readily available plants in late winter, when this article was published. The same technique can, however, be applied to outdoor plants during the summer. There is no difference between taking cuttings of a houseplant and of a shrub or perennial. It’s exactly the same thing.

Stem Cuttings Step by Step

Cuttings succeed more readily when the plant is actively growing, therefore in spring and summer. Rooting is slower and the failure rate is greater on cuttings taken in late fall or early winter, when days are short. We are therefore entering “cutting season,” at least when it comes to houseplants. In early March in the Northern Hemisphere, indoor plants are just starting to emerge from their winter torpor thanks to the longer and longer days.

1. Start by preparing the container you’ll use for the cutting. A classic plastic flowerpot would work perfectly, but you can also recycle a yogurt tub or other container. Of course, you’ll have to punch drainage holes into the bottom of pots that don’t have any. Avoid large pots, as the soil there tends to stay soggy for extended periods. Plants root better in small pots about 2 ½ to 4 in (6 to 10 cm) in diameter, as they allow the soil to dry out a little more quickly and that increases air circulation to the roots that are forming. Alternatively, you can also put several cuttings in a larger pot or tray, preferably a shallow one.

2. Fill the pot with potting soil. That can be “houseplant soil” or “seed-starting soil” or just perlite or vermiculite. Avoid garden soil and even compost, as you’ll want the most sterile potting soil possible.
3. Moisten the soil well and allow any excess water to drain away.

4. Using a pencil or pen, punch a hole in the potting soil in the center of the pot: the hole you’ll be slipping the cutting into.

5. Now take a section of healthy stem using a sharp knife or pruner. Make sure it has at least three nodes and preferably four or five. (A node is the place on the stem where leaves are attached or were previously attached.)

6. Remove flower buds and flowers (they’ll sap the energy of the cutting if you leave them on). You should also remove any lower leaves that will be covered in soil. There should be enough bare stem so that at least 2 nodes can be covered.

7. For plants that you want to see branch profusely, such as coleus and hibiscus, pinch off the tip of the cutting. This stimulates it to produce several new stems rather than just one. For plants where a single stem is the desired form (dieffenbachias, dracaenas, yuccas, etc.), pinching isn’t necessary.

8. Easy-to-root plants include philodendrons, coleus, pileas and begonias. All have soft, green stems with no woody bark and root readily. Woody plants, such as hibiscus, dracaenas and crotons, are more difficult. They root more slowly and the risk of failure is greater. For these plants, buy a root hormone (available in garden centers). Using a cotton swab, brush this product on the lower part of the cutting. The hormone will stimulate those recalcitrant stems to produce roots.
9. Slip the cutting, bottom part down, of course, into the previously prepared hole, to the second or third node. Gently tamp the potting soil so that the cutting stands upright. (For a very large cutting, a stake may be needed to solidify it.)

10. The vast majority of cuttings root best in high humidity and so should be rooted under glass. After all, fresh cuttings don’t yet have roots and when they lose water to evaporation, can’t readily replace the moisture they have lost. If the air is dry, they therefore lose water very quickly, especially thin-leaved species. However, if you place the cuttings under a clear plastic dome or inside a clear plastic bag (“under glass” or “in a mni-greenhouse” in gardening parlance), the air will remain very humid. Indeed, the humidity level in such a structure is often near 100%!
    As a result, the cutting won’t lose moisture through transpiration, giving it a better chance of recovery. So, do cover your cuttings with a dome or a transparent plastic bag*.

*Yes, you can seal the plastic bag. Plants breathe perfectly well inside sealed containers. There is no need to “leave an opening” so the plant won’t suffocate!

11. Place the pot in a well-lit location, but out of direct sunlight, and also in a relatively warm spot (21–24°C). A heating mat can be useful if the room is cool.
12. At this point, there’ll be a bit of a wait until rooting occurs. Some cuttings root very quickly (coleus in just four to seven days!), but others can take two or three weeks. Many woody cuttings take from 1 to 6 months!

You’ll know the cutting is successful when you see new leaves beginning to appear, a sign that the roots are starting to do their job. At that point, give the cutting a bit of a tug: if there is resistance, it has rooted. You can then remove the mini-greenhouse and place the plant (it is no longer a cutting) in a place suitable for its needs, treating it like an adult plant.

Yes, you have successfully grown a plant from a cutting! Now, that wasn’t hard, was it?

Starting Cuttings in Water: Old Tradition, Bad Idea

The following text will surprise many gardeners, as there is a long tradition of starting cuttings in a glass of water. But placing cuttings in water is “bad horticulture”: an extra step that is both unnecessary and risky.

I’m not saying that cuttings placed in water don’t root well. Sometimes they do and in fact, everything often seems fine at first. It is rather at the end of the process, when the time comes to pot up the rooted cutting into soil, that failure occurs.

The problem is that the roots produced on a cutting placed in a glass of water acclimatize to an aquatic environment. When you transplant the cutting into a pot later (and very few plants can spend their entire life in water), the fragile aquatic roots clump up and are often damaged, so rot sets in. As a result, the poor cutting is forced to start all over, producing a new batch of roots even as it is struggling to fight off rot. Often, it no longer has enough reserves do so and dies.

So, to ensure a good success rate, I suggest always starting your cuttings directly in potting soil. It’s less of an effort and gives superior results.

If You Insist on Starting Cuttings in Water. . .

If you absolutely insist on starting cuttings in water, here’s a reasonable compromise that should give you good success.

So, yes, place your cuttings in a glass of water, but take them out of the water and pot them in potting soil as soon as you see the first signs of root initiation. That is, when the roots are just small white or yellow bumps on the stem. Don’t wait for the roots to stretch out into the water. You don’t want to encourage the formation of aquatic roots, but rather terrestrial roots. Just pot up your cuttings with sprouting root buds into potting mix and keep them moist to allow real terrestrial roots to grow.

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Now that you know how to take cuttings, you’ll discover your thumb is greener than you thought!