If you’ve looked into propagating your Dieffenbachia, you probably know that you can get cuttings to take root in water. But can you leave them there long-term, or will you eventually need to move your plant to the soil? Will a Dumb Cane grow and thrive in just water, with no potting mix at all?
With proper care, Dieffenbachias will tolerate water-only cultivation surprisingly well for such a large, thick-stemmed plant. They don’t usually grow as quickly as they would if rooted in soil, but they can survive and produce beautiful, vigorous foliage.
If you want your Dumb Cane to grow in water instead of just surviving, you’ll need to supply some fertilizer; the plant won’t have access to the nutrients typically found in potting soil. A small amount of water-soluble fertilizer every few weeks during the growing season should be plenty. Keep reading to learn more about the pros, cons, dos, and don’ts of growing a Dieffenbachia without soil.
How Can a Houseplant Grow Without Soil?
Dumb Canes aren’t aquatic plants in the wild. However, they do have a knack for adaptation that they share with a surprising number of other land plants – the ability to grow a new kind of root when submerged.
These not-so-creatively named “water roots” are capable of extracting oxygen from water, sort of like the gills of a fish, enabling the plant to survive without the tiny air pockets it normally needs in the soil. They’re more fragile than soil roots, but they’re also less prone to root rot.
This may have evolved as a survival mechanism to help Dieffenbachia survive if they happen to take root in a low floodplain or the edge of a stream, where they might be swamped in water for weeks or months at a time.
Benefits of Growing Dieffenbachia in Water
Okay, so it’s possible to grow your Dumb Cane in water – but why would you want to? As it turns out, a hydroponic (water-only) setup does offer a few advantages:
Number 1: No More Watering Worries
Bizarrely enough, it’s easier to drown your Dieffenbachia in soil than in water. The roots that a plant develops in potting mix can’t breathe underwater, so if you accidentally swamp them, they’ll suffocate. On top of that, the bacteria and fungi that live in soil can breed out of control in a waterlogged environment, leading to one of the top killers of houseplants: root rot. A Dumb Cane rooted in water from the beginning won’t have these issues.
And, of course, there’s little to no risk of your Dieffenbachia going thirsty, unless you ignore it for so long that the water in its container is all absorbed or evaporated.
Number 2: Easy Repotting
Houseplants, especially fast-growing ones like Dieffenbachias, have to be transplanted periodically so that they don’t outgrow their pots. With a Dumb Cane that’s dug into soil or a soil-like potting mix, this is a bit of a production. You often have to tilt and smack the pot to jog the plant loose, then break up the clods clinging to the roots by hand. And once you’re done, you have to clean up all the dirt you’ve spilled.
Moving a plant from one jar of water to another is far simpler. All you need to do is pick it up, rinse it off, and plunk it into the new vessel.
Number 3: Visible Root System
Issues like root rot and fertilizer burn are especially tricky because they’re hard to diagnose until they affect the foliage. But if you grow your Dumb Cane in a clear container of water, you can see at a glance whether there’s anything wrong with its roots.
This has aesthetic benefits, too – there’s a certain visual appeal in seeing roots curling around the inside of a vase, jar, or test tube. You can augment this look by adding colorful beads or interesting pebbles.
Drawbacks of Growing Dieffenbachia in Water
Despite the benefits we’ve listed above, raising hydroponic Dumb Canes isn’t all sunshine and roses. There are some significant disadvantages to keep in mind:
Number 1: Frequent Upkeep
A Dieffenbachia living in water is a bit more high-maintenance than one in soil. For one thing, you’ll have to change the water out on a regular basis to refresh its oxygen content and avoid algae buildup. You should also pluck out any scraps of leaves or stems that fall into the jar; you don’t want them decomposing in there with your plant.
Plus, you’ll have to supply regular doses of nutrients, because you don’t have the option to just add compost or slow-release fertilizer into the potting mix as you would with a soil-grown Dumb Cane.
Number 2: Growth Restrictions
Under normal circumstances, Dumb Canes grow fairly fast. Many cultivars will get taller than their owners if given enough time! In a jar of water, your Dieffenbachia probably won’t reach quite the same impressive heights, and it won’t grow as quickly.
Of course, some owners will see this as a feature and not a bug. Trying to keep a Dieffenbachia standing upright when it’s nearing five feet tall can be a challenge, after all! Note that if your hydroponic Dumb Cane does develop a long stem, it will require more support than normal, because it won’t have the soil to anchor it.
Passive vs. Active Hydroponics
Before we get into the specific instructions, please note that the system we’ll be describing below is a passive hydroponic setup. All of the tubes, pumps, fans, and grow lights that you might be picturing are for an active hydroponic approach, which is usually employed by people looking to grow commercial crops.
Passive hydro doesn’t require nearly as much equipment or precision. It doesn’t allow you to maximize crop yield in the same way that active hydro does, but that’s usually not a concern for houseplant owners.
How to Transfer Your Dieffenbachia to Water
Dumb Canes aren’t usually sold in vases, so if you’re going to try to grow yours in water, you’ll probably need to switch one over from soil. The simplest way to do this is by taking a cutting. Like many plants, Dieffenbachias can produce new roots from even small segments of their stems.
Before you start slicing, you’ll need to have a container ready. Any kind of jar or vase will work, but a wider base and a longer neck will offer more stability as the plant gets taller, while a narrow mouth might cramp the stem as it grows thicker. Clear glass often has more visual appeal, but also tends to be more prone to algae growth, so you’ll have to clean it more often.
Fill the container about half-full with water. We recommend distilled water, though tap water is usually fine as long as you let it sit overnight to let any chlorine evaporate. Rainwater is even better if you can collect enough.
Next, decide how much of the existing plant you want to switch over. You’ll have the best results with a stem section that’s at least 6 inches long. Before you cut, sanitize your pruning shears or garden knife using rubbing alcohol or a 10% dilution of bleach. You should also wear gloves, because the sap from a Dieffenbachia may cause painful skin irritation.
Slice through the trunk at a 45-degree angle, just below a node – one of the narrow bands of lighter-colored tissue that break up the trunk of your Dumb Cane. These are where the new roots will grow from your plant.
Trim away most of the foliage, starting at the lowest part of the stem and working your way up. Until the root system gets established, your Dieffenbachia won’t have the energy to support more than a few leaves.
Now place your plant in its new container. Make sure the water level is high enough to cover at least three or four of the nodes.
Caring For a Dumb Cane in Water
As we explained above, growing a Dieffenbachia in water calls for frequent maintenance. You should change out the water every 1-3 weeks, depending on its condition – change it right away if it starts to smell or grow algae.
When you swap the water out, it’s a good idea to rinse off the roots as well, to wash away any slime that’s beginning to build up there. If you see signs of rot or algae, give the entire jar a good scrub.
Your Dumb Cane will need some fertilizer, but don’t overdo it. During the growing season, you can add a couple of drops of hydroponic fertilizer to the water every 3-4 weeks. Scale back your dosage if you notice the roots or leaves crisping up, and don’t give your Dieffenbachia any nutrients during the fall and winter – it isn’t getting enough light to make use of them.
Keep an eye on the pH, too. Pure water doesn’t have the buffering qualities that soil does (though some hydroponic fertilizers do), so you may need to adjust it to keep it in the 6.1-6.5 range where Dumb Canes thrive. A simple pH testing kit like this one will have everything you need to calibrate the acidity of the water.
Other than that, you should treat your plant like any other Dieffenbachia. Keep it in a bright spot but out of direct sun, maintain a temperature between 65 and 80 degrees Fahrenheit, and rotate it regularly to keep the stem growing straight.
Semi-Hydro for Dieffenbachias
Semi-hydroponic culture offers a middle ground between potting mix and pure water. This technique uses a uniform, absorbent growing medium to anchor your plant’s roots, with a reservoir of water underneath. The pores in the substrate allow your Dumb Cane’s roots to draw water up via capillary action without being fully submerged.
This is a bit more expensive and time-consuming than a full hydro approach, but the solid substrate provides more support for your Dieffenbachia as it grows.
There are two basic versions of a semi-hydro setup. The first is to keep the plant and substrate in a net pot or some other porous container, setting it inside a tray or cachepot that holds the water. The other option is to use a single tall container made of glass or plastic, filling the bottom ¼ to ⅓ with water.
You have a few choices for the substrate:
- LECA. Small balls of clay that have been heated to fill them with tiny pores. Pricy but effective, and reusable if you clean them. We have a more detailed article on using LECA for houseplants here.
- Pumice or some other volcanic rock. Provides a slightly more organic appearance, while still doing an effective job drawing up moisture.
- Perlite. This chunky, spongy rock is usually mixed in with soil to add aeration, but it can easily be used as a standalone growing substrate.
Moisten your growing medium thoroughly before placing it in the pot. Then move your plant into its new home. You can root a cutting of your Dieffenbachia as described above, or transfer your entire plant, roots and all. If you take the latter approach, make sure you clean all the soil off the roots before you replant them.
After that, it’s mostly a matter of periodically changing out the water and adding fertilizer, just as you would with full hydro. The main difference is that you shouldn’t uproot and rinse your Dumb Cane every time you swap out the water – unless you see rot that needs to be removed, you shouldn’t disturb the plant’s root system.
A hydroponic approach probably won’t let you grow a Dumb Cane to the same towering heights it could achieve in soil. But you might consider that a fine tradeoff in exchange for never needing to worry about overwatering. If you keep the above advice in mind, you should be able to raise a perfectly happy Dieffenbachia in water alone.