Propagating stem cuttings in water involves cutting a piece of the parent plant and placing it in a container filled with water. You allow the cutting to develop roots and then move it to a container filled with soil, though you can choose to keep some plants in water.
Growing stem cuttings in water is easier than starting them in soil. It also takes the guesswork out of the equation because you can see the roots as they develop. You aren’t left wondering if you are doing all the right things to raise your new plant.
Many herbaceous houseplants can be propagated this way. African violet, begonias, hoya, Monstera, philodendron, Pothos, and ZZ plants. With few exceptions, aroids or arums (plants in the Araceae family) propagate well this way.
Most hardwood plants won’t propagate in water. They will rot before the roots can form. There are a few exceptions, however. Ficus plants like fiddle leaf figs (Ficus lyrata) and rubber trees (F. elastica) will propagate in water if you take softwood cuttings.
When to Take Cuttings
Part of finding success with stem cuttings is being able to produce roots before the cutting runs out of nutrients and begins to die. For that reason, you want to take cuttings when the plant has the best chance of producing healthy growth.
Cuttings should be taken when the plant is actively growing and not in bloom. Many plants go dormant in the winter. When a plant is dormant, it isn’t actively producing new growth, or the growth is slowed down.
Similarly, if you take cuttings when the plant is in bloom, it’s putting energy into producing its reproductive blossoms rather than in producing new root growth.
Take your cuttings during the spring, summer, or fall, so long as plant isn’t blooming.
In order to propagate a cutting in water, you need a container to hold the water and the plant. Clear containers work best because you can see the roots developing and determine when it’s ready to move into some potting soil.
You will also need a clean pair of clippers, pruners, a knife, or scissors to remove the cutting. Make absolutely sure that you clean your tool before using it. Wash it in warm, soapy water and wipe it with isopropyl alcohol to remove any harmful pathogens that could cause disease.
Take the Cutting
Aroids or arums have what are called adventitious roots. These are roots that grow above the soil line. Many have roots that grow along the stems in between the leaves. Look at a Pothos, for instance. You will see little brown bumps in between the leaves. These are the root nodes, which may or may not develop into roots.
When you take a cutting, be sure to include one or two of these at the lower end of the piece that you remove. Roots will more readily develop from these areas since they already contain the genetic material for root development.
For plants that lack adventitious roots, take a cutting just below a leaf node.
Use your knife, scissors, pruners, or clippers to take the cutting at a 45-degree angle. You want a cutting that is soft and pliable, not hard. It should be about six to eight inches in length.
The 45 degree angle is important because it creates more surface area for roots to develop and prevents the base of the cutting from sealing onto the base of the container.
If you are taking multiple cuttings, place them in a cup of water as you work so they won’t dry out, and the pores won’t close.
Prepare the Cutting
Whether you took a cutting with adventitious roots or not, remove all but the top two or three leaves for plants that have small leaves, or all but one leaf for plants that have large leaves, using a clean pair of scissors or clippers.
These leaves take up resources that the plant can no longer support since it doesn’t have roots. You want to give it just enough foliage to photosynthesize but not so much that it can’t support the foliage long enough to develop roots.
If the cutting has dried out at the base while you were working, re-cut the base to open up the pores.
Place the cutting in a container filled with lukewarm water. You can add a drop of bleach for every two cups of water to kill any pathogens that could potentially harm your plants.
The cutting should sit with the leaves well out of the water and should only be submerged by less than half. If you need to prop the cutting up, you can use chopsticks or wire laid on the top of the container.
The base of the cutting should not sit parallel to the bottom of the container, or you run the risk that the cutting might seal onto the container and won’t be able to take up water and oxygen.
Part of what makes propagating in water appealing is that it requires little care. Change the water every few days and wipe out the container to prevent algae or fungi from forming.
Otherwise, you simply need to place the cutting in an area with the appropriate light for the species. Unless the cutting starts to droop, drop leaves, or turn brown or yellow, wait for the roots to develop and keep changing the water regularly.
How to Know It’s Ready
It’s easy to tell when a stem cutting in water is ready: you will see lots of root growth. There is no hard rule on when you can transplant the cutting. Wait until there are at least several root branches that are at least an inch or two long before you transplant them into soil. It doesn’t hurt to wait a little extra time to ensure the cutting is completely ready.
Soil roots and water roots are different from one another. Roots that develop in soil have more resistance to work again, so they are larger, sturdier, and adapted to absorb oxygen and moisture from within the growing medium.
Water roots are lighter, have more hairs, and are more fragile. They have adapted to draw nutrients and oxygen from the water and are ill-equipped to function in soil.
As a result, when you transplant your cuttings into soil, the plant will experience a short period where it is particularly fragile as it develops roots that are better adapted to soil or a potting medium.
For that reason, you’ll need to be careful to keep the plant watered and away from stressors like too much sun, strong breezes, and cold temperatures.
After a few weeks to a month, the plant should have developed some sturdier soil roots, and you can treat it as you would normally.
If you opt to leave your plant in water, you need to set it up so that the green parts of the plant are above water and just the roots are submerged. You can find containers that are made to support this type of growth.
You may want to fill the water container at least partway with rocks to add weight and prevent your plant from tipping over.