What Type of Soil is Best for Arrowhead Plant?
The wrong type of potting mix can be the difference between a thriving arrowhead plant and a struggling one.
How to make sure that you get the best potting mix for your arrowhead? By doing a bit of research, of course!
The soil in the native lands of arrowhead plants has certain properties that you will need to mimic to ensure the best care for your arrowhead plant.
I’m going to discuss the type of soil needed for arrowhead plants, its characteristics, and what happens if you use the wrong kind of soil.
Properties of Good Soil for Arrowhead Plant
Arrowheads are native to tropical and subtropical rainforests in Central and South America. The soil in these regions is well-draining, slightly acidic and rich in organic matter.
Therefore, when choosing a soil for your arrowhead plant, you must have the following properties in mind:
There’s a common belief that soil in rainforests is extremely fertile due to the abundance of organic matter available there. This isn’t necessarily the case, however.
While it’s true that there is an abundance of organic matter, this usually breaks down very quickly due to the amount of precipitation available and it’s just as quickly depleted by the vegetation that needs to be sustained.
Therefore, nutrients don’t have time to build up in the soil because they get stripped away immediately by heavy rainfall and other vegetation.
Still, arrowhead plants need soil that contains organic matter, and soil that is somewhat fertile to sustain its growth and development.
Commercially available potting mixes for aroid plants will usually have some organic matter such as compost to make it more fertile. Compost also helps with better drainage and moisture retention.
– Good Drainage
Given the amount of precipitation available in tropical regions, you would think that the soil is drenched in water all the time. That’s simply not the case.
In fact, the soil there is well-draining, which is another explanation why nutrients can be ‘recycled’ or stripped away relatively quickly, leaving no time for them to build up in the soil.
Good drainage is essential for pot-grown arrowheads. If the roots stay in water for too long, they will start to rot, which will threaten the very existence of the plant.
Therefore, provide fast-draining soil that doesn’t become waterlogged, so that excess water can drain away. The longer for the water to drain, the higher the chances for fungal issues and rotting.
Potting mixes formulated for arrowhead plants will contain different types of substrates such as orchid bark, coco peat, and perlite, which help with the drainage of the soil.
– Moisture Retention
Because arrowheads are accustomed to constantly humid soil, the soil needs to have another essential property, namely, to retain moisture.
You would think that fast-draining and moisture retention are opposite qualities of the soil, but that depends on what’s the makeup of the soil.
Moisture-retention is not the same as water-retention. Some substrates hold only a bit of moisture without becoming waterlogged.
Then there are substrates that can hold a lot more water to the point where they become saturated with it. These take a long time to dry.
The longer it takes for a potting mix to dry, the higher the chances of fungal issues developing in the substrate and the higher the risk for root rot.
Arrowheads need a potting mix that can hold some moisture while at the same time draining properly. The roots should only be moist, not wet.
– Good Aeration
A further property of arrowhead plant soil is good aeration. A soil that’s aerated is loose and doesn’t become compacted around the roots.
Aeration is a quality of the soil that’s related to structure. The potting mix for arrowhead plants needs to allow a good movement of the air through the soil structure.
Again, this will prevent waterlogging, wet roots, and ultimately rotting issues. Orchid bark, perlite, peat are all substrates that combine loosely, allowing the substrate to “breathe”.
Aeration is once again crucial to prevent root rot, bacterial, and fungal overgrowth, so that the roots of the arrowhead plant stay healthy and undamaged.
So, while surprising, aeration is another must-have quality of the arrowhead plant soil.
– ph Level
Arrowhead plants prefer slightly acidic soil, somewhere in the range of 5.5 and 6.5. If you’re buying a commercially available potting mix formulated for arrowheads or aroid plants, you don’t need to measure the pH of the soil.
If you’re creating your own potting mix, then you might need a pH meter to check the pH level of the soil.
So far, I’ve described the properties of good soil for the arrowhead plant, pointing out the reasons why these qualities are needed or desirable.
One soil type that will not check off all these requirements is regular potting soil. Using regular potting soil on its own will cause problems for your arrowhead plant.
Below, I will discuss the drawbacks of not using the right soil for your arrowhead plant and what you can expect to happen as a consequence.
Consequences of Using the Wrong Soil
Now that you know why it’s important to choose an adequate soil type for arrowhead plants, I will also list the side-effects of using the wrong type of soil:
– Slow Growth
A bad potting mix can cause stunted growth in arrowhead plants. As the plant struggles with compacted soil or waterlogged soil, or if its roots become affected by root rot, it can become difficult for the plant to grow.
Arrowhead plants that are grown indoors, reach an average height or length of 6 to 10 feet. Without the right potting mix, your arrowhead plant will have developmental issues including slow and stunted growth or small leaves.
Because it’s difficult to maintain the watering regimen needed for arrowhead plants if the soil does not help in terms of drainage and aeration, it will be very difficult to prevent root rot problems on the long run.
– Brown Leaves
Brown or browning leaves can also be an effect of poor soil quality. Beyond browning caused by root rot issues, brown leaf margins can also be a consequence of mineral salt build-up in the soil.
Mineral salts can build up in potting mixes that don’t drain well much faster than in well-draining soil. This can affect the health of the leaves and stems.
When browning leaves are caused by root rot, it’s because the roots can no longer deliver nutrients to the plant and tissue damage sets in.
Although brown leaves can be caused by other issues as well, including thermal shock and pests, the quality of the soil can just as easily manifest itself as changes in leaf color.
– Yellow Leaves
The leaves of your arrowhead plant can also turn yellow when the potting mix isn’t what is supposed to be.
An overwatered arrowhead plant grown in regular potting soil will often display this very symptom.
Just like browning leaves, yellow leaves can also signal other problems as well. From overfertilizing to exposure to direct light, the quality of the soil is not the only one to cause a change in the color of the leaves.
If you’ve excluded all other potential causes and you’ve been using poor quality soil, I recommend you replace the soil of your arrowhead plant before things take a turn for the worse.
– Wilting Leaves
Wilting leaves can be a sign of overwatering but also a sign of underwatering. If you’re growing an arrowhead plant in regular potting soil, both things can be a likely explanation for why the leaves are wilting.
As I already explained, soil that gets saturated with water can become compacted when it dries. This can strangulate the roots of the plant and leave them dry, causing wilting leaves.
The other extreme is also true. Watering the plant too often and not allowing the soil to dry will cause the roots to sit in water for too long, leading to root rot. In this case too, leaves can start wilting.
An easy fix and the thing I always recommend to do first, is to replace the potting soil with a mix formulated for aroid plants.
– Root Rotting
All the above symptoms – yellow leaves, leaves turning brown, wilting leaves, etc. – can be symptoms of a much bigger issue: root rot.
Root rot is caused by overwatering, which triggers bacterial and fungal overgrowth in the soil and other chemical processes that result in the roots starting to rot.
This is where a loose, well-draining and well-aerated soil can reduce the risks of root rot, especially if the plant is watered correctly.
All these things are interconnected – you need adequate potting mix but also adequate watering techniques.
It can be difficult to correctly water an arrowhead plant, simply because it’s all about making sure you’re correctly assessing the humidity levels of the soil.
If the soil goes too dry, the plant will become dehydrated. If the soil retains too much water, it can become waterlogged, and cause rotting.
One of the easiest ways to keep watering under control is to water the soil uniformly until you notice water pooling at the base of the pot.
Empty the saucer and don’t water the plant until you can determine that the top layer is starting to dry out. You can make that assessment by poking a finger in the potting mix.
When to Repot Arrowhead Plant?
Arrowhead plants grown indoors don’t have such a fast growth rate as other vining plants. You can easily wait for 2-3 years before having to repot an arrowhead plant, although I recommend that you replace the potting mix every 2 years.
Routine repotting should be done in spring, when the plant’s metabolism is kicking into high gear after a winter of dormancy.
There are exceptions. If you need to repot because of bad quality soil that’s starting to affect the plant or if you suspect root rot issues, you may replace the potting mix as soon as possible.
What Type of Pot to Use for Arrowhead Plant?
You may think that the type of pot, and more specifically, the material of the pot has no consequence for the well-being of the plant.
Most plant owners will use plastic. And that can be a fine choice for most houseplants, however, I don’t recommend them for houseplants that are sensitive to root rot.
Plastic does not allow the soil to dry as fast as it’s desirable for these types of plants and locks moisture.
In my experience, terracotta pots that are unglazed are a much better choice. The porous structure of the terracotta absorbs excess water and allows the soil to “breathe” rather than locking all that moisture in.
Making Your Own Potting Mix for Arrowhead Plant
I already mentioned that you can create your own potting mix for an arrowhead plant if you don’t want to buy pre-mixed substrates.
The best soil mixes for arrowhead plants combine peat moss, perlite, orchid bark and a bit of compost.
If you already have these around the house, you can easily combine them for your arrowhead plant.
I sometimes use a mix of half vermiculite or peat moss and half perlite, other times I use one part perlite, one part regular potting soil, and one part peat. I also add a bit of compost in there.
I’ve also successfully used African violet potting mix, since they need the same type of soil as arrowhead plants.
So, I use whatever well-draining potting mix I have around the house, but commercially available aroid potting mixes are an excellent choice if you don’t want to bother with putting together your own mix.
I hope that I’ve managed to explain why it’s important to use soil that’s formulated for arrowhead plants and why it’s not a good idea to forgo the recommendation to avoid using potting soil on its own.
Using the type of soil that’s best for arrowhead plants will go a long way in helping the plant develop normally and eliminate some of the sensitivities associated with these plants.