Dumb Canes can be vigorous and resilient plants, but they’ll only truly thrive if you can provide the growing conditions they need. Good care begins with a good pot and potting mix, which together serve as the foundation (pun definitely intended) of healthy houseplant growth. This article will explain how to give your Dieffenbachia a container and a soil blend that will help it flourish.
The ideal soil for Dumb Canes is one that will stay mildly damp without holding excess water. Use a potting mix containing a large fraction of chunky, drainage-boosting elements like perlite or conifer bark chips, along with some spongy materials like peat moss or coconut coir. If you have to use a store-bought mix, choose one intended for African Violets.
No matter what container you choose, it should have holes in the base. If there’s no way for water to escape, you’re likely to suffocate your Dieffenbachia even if the soil has excellent drainage. Those who are especially worried about watering too much may want to choose a terra cotta pot, which lets water evaporate faster. Read on for more detailed information on the best pots and potting mixes for Dumb Canes.
Note: Soil vs. Potting Mix
Discussions about houseplant soil can be a bit confusing because many indoor plants don’t live in soil at all. True soil is the substance you find when you dig into a field, forest, or garden. It includes earthy minerals like sand, silt, and clay, along with decomposing organic matter and lots and lots of microorganisms.
Garden soil is great for growing plants outdoors, but in the cramped confines of a pot, it often compacts too much to permit healthy root growth. Most indoor gardeners prefer to use soilless potting mixes that are made up of lighter ingredients. To make the whole thing even more confusing, some products labeled as “potting soil” are actually soilless blends, while others include actual soil.
For the sake of convenience, we’ll use the word “soil” in this article to refer to whatever growing medium you’re using for your Dieffenbachia, but remember that we’re not advising you to use actual garden soil or topsoil in your pot.
What Kinds of Soil Are Best for Dumb Canes?
When it comes to potting mix, there are a few important variables that you’ll want to get right to make sure that your Dieffenbachia can reach its full potential. The first, and most critical, is drainage.
Novice houseplant owners are far more likely to drown a Dumb Cane than let it die of thirst. Although your plant’s roots need water to live, they need oxygen too. When the soil is soaking wet, there’s no room for air, and your Dieffenbachia’s roots will be smothered.
This problem is made worse by the fact that some fungi and bacteria reproduce much more quickly in a soggy and airless medium. They can invade your plant’s weakened root system, leading to root rot, a nasty condition that can kill your Dieffenbachia if you don’t treat it as soon as possible.
You can avoid this problem by being careful not to water your Dumb Cane too much, but that’s much easier if the water can drain out of the growing medium quickly. Soils containing lots of fine particles tend to trap and hold a lot of moisture. This greatly increases the chance that the roots will suffocate or get infected. Your plant will be better off in a looser, airier mix.
Nutrition is another consideration. In the wild, Dumb Canes absorb lots of nutrients from rainwater, dissolving rocks, and decaying plants and animals. We’re going to go out on a limb and guess that you don’t have those things in your house. One way to supply the nutrition your Dieffenbachia needs is to include some compost or slow-release fertilizer in its potting mix.
The pH of the mix will also affect how readily your plant can absorb the nutrients it gets. Dumb Canes like their soil very slightly acidic, between 6.1 and 6.8 on the pH scale.
Store-Bought Blends for Dieffenbachia
Mass-produced commercial potting mixes are much better for houseplants than garden soil, but they’re often a bit low on drainage for drought-tolerant plants like Dieffenbachias. Still, you can usually get away with using a store-bought mix, but you should be very attentive to avoid overwatering. Your Dumb Cane will generally be safe if you wait until the top 2 inches of soil have dried out before giving it more hydration.
Dieffenbachias often do well in potting mixes blended for African Violets, which have similar moisture requirements. You might also get good results with a boutique high-drainage option like this one, though these tend to be pricier and require more frequent watering.
One advantage of store-bought mixes is that they typically have nutrients mixed in, so you won’t need to fertilize for a while.
Potting Mix Ingredients for Dumb Canes
Making your own potting mix is a great option if:
- You want to make sure that your Dieffenbachia’s growing medium has plenty of drainage
- You’re interested in testing and experimenting to find the perfect blend
- You simply enjoy DIY projects
So let’s talk about what goes into a good substrate for Dumb Canes. Your ingredients will fall into two basic categories. First, there are big, chunky ingredients that boost your drainage, such as:
- Perlite. You may be familiar with perlite as the hard white chunks in store-bought potting mix. It’s a kind of volcanic glass that’s very lightweight and porous. Perlite is available in a broad range of grades, but we’d recommend using the coarsest kind you can find for your Dieffenbachia mix.
- Crushed pumice. This is another type of airy volcanic rock, but it’s often sold in even larger particle sizes than perlite.
- Horticultural charcoal. Lighter than perlite, and potentially more eco-friendly. Make sure you get the kind that’s specifically sold as a horticultural soil amendment.
- Bark chips. Scraps of bark from various kinds of conifer trees are commonly used as a growing medium for orchids, but they work well in tropical houseplant blends too. Depending on the kind of tree they come from, bark may lower the pH of the soil a bit, which can be helpful for Dumb Canes depending on what else is in the mix.
- Coconut husk chips. Higher in pH than bark chips, but otherwise these have very similar properties.
The other main category is springy, water-retentive organic materials. While your mix should be able to shed excess water, you don’t want it to completely dry out before you water it again. These ingredients can absorb a bit of moisture to keep your Dumb Cane’s roots hydrated:
- Sphagnum peat moss. This has long been a standard addition to potting mixes, but in recent years many people have grown concerned about the ecological impact of harvesting it from peat bogs. It’s quite acidic, so you may need to add garden lime as a balancing agent.
- Coconut coir. The most common alternative to peat moss, coir is quite similar in terms of water retention, but it’s more or less pH-neutral. Many consider it more sustainable than peat since it’s an upcycled waste product – though since it has to be shipped from farther away to reach the United States, the ecological comparison isn’t completely open-and-shut.
- Compost. Decomposed organic matter which provides some natural nutrition while also acting as a moisture sponge, compost makes a great addition to most potting mixes. It’s not a perfect substitute for peat or coir, but it can be a helpful supplement. We’d recommend using vermicompost, also known as worm castings, due to its beneficial effects on the soil microstructure.
Putting Your Dieffenbachia Mix Together
You’ll want to experiment with various ratios of these ingredients to figure out what works best for your plants and your gardening style. In general, at least half the total volume of your potting mix should come from the first list. Otherwise, the smaller particles will just fill in the gaps between the big chunks, canceling out any aeration you would get from the coarse ingredients.
Note that your chunky ingredients have to be mixed in with the rest of the soil to have a beneficial impact. It used to be common to place a layer of rocks or gravel at the base of the pot to “improve drainage”, but this actually has the opposite effect. The soil still holds onto the same amount of moisture, but the gravel is taking up valuable space in the pot, making it even more likely that the roots will be stuck in the saturated zone.
A good starting blend for Dumb Canes is 40% coarse perlite, 25% orchid bark, 25% coconut coir, and 10% vermicompost. If you want to use some commercial potting soil, you could blend equal parts perlite, orchid bark, and African Violet mix.
Blend your ingredients together thoroughly in a large plastic tub. Perlite tends to produce a lot of dust, so make sure you’re working in a well-ventilated area, and consider wearing a painter’s mask.
Choosing a Pot For Your Dumb Cane
Once you’ve whipped up a nice crumbly growing medium for your Dieffenbachia, you need somewhere to put it. The one and only requirement is that you choose a container with a hole in the base. You’ve gone to a lot of trouble to mix up a well-draining soil, so don’t spoil it by trapping the water inside the pot.
What if you happen to find an absolutely gorgeous container that doesn’t have drainage openings? If it’s made of plastic, you could simply add some holes with a power drill. Otherwise, you can use it as a cachepot. Plant your Dieffenbachia in a slightly smaller nursery pot that does have drainage holes, then tuck it inside the cachepot.
This will create a little more work for you when it comes time to hydrate your plant. You’ll have to take your Dumb Cane out of the cachepot, water it, and put it back once the extra water has drained out. You could also water the plant as normal and empty the cachepot a little while later, though this somewhat risky option if you’re the forgetful type.
What about the material of your pot? In practice, this doesn’t have much of an impact – you can use anything from a glazed ceramic work of art to a plain plastic bucket. As long as it has drainage holes, your Dieffenbachia won’t care.
The one exception is unglazed terra cotta. This material is very porous, allowing liquid to escape the soil much faster. It’s a bad choice if you often forget to water your plants, and a good choice if your main concern is overwatering.
Pot Size and Repotting
Eventually, if you’re taking good care of your Dieffenbachia, you’ll need to move it into another pot. The exact time frame will vary from plant to plant, but you should generally repot every 2-3 years – if only to refresh the potting mix.
Sometimes your Dumb Cane will send some signals that it’s ready to move out. Its roots may start to poke up through the top of the soil or out through the drainage holes. It might also slow down its growth because there’s no more room for its roots to expand. These are all signs that it’s root bound, which basically means that the root system is squishing up against the sides of the container.
When you’re moving your plant to a new pot, it’s best not to increase the size too much. An overly large pot won’t make your Dieffenbachia grow faster, it will just increase the likelihood of overwatering (since a greater volume of soil takes longer to dry out).
When repotting, give your Dumb Cane a container that’s around 2 inches larger in diameter than its old one. You may want to do this the first time you bring it home from the garden store; it’s common for potted plants to be somewhat root bound by the time they’re sold.
Making the effort to get your Dumb Cane’s soil right will go a long way toward ensuring that it survives and grows strong. You’ll have a much easier time keeping your plant properly watered and fed if it’s in the right container and potting mix. Keep our advice in mind, but don’t be afraid to experiment – it may take a few tries, but you’ll find a blend that your Dieffenbachias love.