ZZ plant is considered one of the best low-maintenance plants, but overwatering is perhaps one of its few weaknesses.
Apart from watering more frequently, overwatering can also be a result of improper soil mix. The wrong soil type can retain moisture longer and cause serious overwatering issues like root rot. Conversely, improper soil can also drain water too quickly, not letting the plant absorb nutrients properly.
Therefore, to benefit from a ZZ plant’s tough qualities, its soil should closely mimic its natural preference. And to understand those preferences, we must begin by answering this question:
What is the Best Soil for a ZZ Plant?
The ZZ plant prefers light, porous, well-draining, well-aerated, and nutrient-rich soil that should also retain some moisture.
Any dense, heavy, dry, and compaction-prone soil is far from ideal (e.g., garden or clay-rich soil). Such soil can hold water a lot longer and lead to serious overwatering issues.
Another medium to avoid is sand. Using sand alone makes up for a light potting medium that does not hold any water, deprives the roots of nutrients and moisture, and leads to underwatering issues.
Simply put, the soil should be primarily well-draining and well-aerated with a limited capacity of retaining moisture. The draining and aeration qualities will help the oxygen flow freely, improve nutrient uptake, and prevent waterlogging. The limited moisture-retaining quality will hold water for just long enough that the roots and rhizomes absorb the nutrients. Lastly, the soil pH to aim for is 6.0-7.0 (acidic to neutral).
Purchasing Commercially Available Soil Mix—Dos and Don’ts
Whether you’re looking for a soil mix online or at a local garden supply store, the options can be overwhelming. Here are a few pointers to keep in mind to make the selection easier:
- Make it a practice to read the list of ingredients of the soil mix you’re interested in. It is even better if the packaging has information about the ratios of each ingredient.
- Choose a potting soil made for houseplants containing components like sand or perlite. This well-draining mix will be perfect for your ZZ plant.
- Check whether the mix contains ingredients like biochar, pumice, or bark. All these ingredients improve aeration and drainage without retaining too much water.
- You can also choose soil mixes advertised as light, porous, or airy. They are usually suitable for ZZ plants, but it is still better to look at their ingredients and see if they contain the additives mentioned above.
- You can also choose a soil mix made for Monstera plants, as it will likely have the same ingredients your ZZ plant needs.
- If you can’t find any of the combinations listed above, simply choose a cactus/succulent mix containing perlite or pumice. These ingredients alone will improve drainage and provide a healthy growing environment for your ZZ plant. You’ll have to add two parts potting soil to the mix to counter the lightness of sand in the cactus mix.
- Lastly, if you want to avoid all the hassle and need a product recommendation, here’s one.
To make your own mix, you’ll need to learn about different soil ingredients and their function. Let’s take a look at them.
Ingredients in the ZZ Plant’s Soil
Potting soil is the basic medium of your soil mix and would be in a greater quantity than other ingredients.
Choose a well-draining, light, and aerated soil mix containing small amounts of organic matter. Steer clear from clay, garden soil, or soil primarily composed of sand.
Perlite’s primary function in the soil is to improve aeration and drainage of the mix. It is a type of volcanic glass available in white and irregularly shaped chunks.
In my opinion, if you simply mix 1:1 perlite and well-draining potting soil, you’ll likely have a good mix for a ZZ plant.
You can use vermiculite as an alternative to perlite. It has a similar structure, and it helps aerate the soil. However, since it retains more water than perlite, adding it in a lower ratio is recommended when using it as an alternative.
Pumice is yet another substitute for perlite with some differences. Firstly, it is more porous than perlite, more expensive, and less readily available. However, like vermiculite, it also retains slightly more water.
It is a type of volcanic rock that is heavier than perlite and stays in the soil longer. It is better to use a smaller ratio when adding pumice instead of perlite.
Sphagnum and Peat moss
Sphagnum and peat moss both originate from the same source. They have a dense structure and can help improve soil aeration. They are also helpful in retaining nutrients for longer.
However, their main downside is their water-retention capability. I recommend using moss in relatively small amounts to prevent waterlogging.
Coco coir is made from coconut husks, and it is an eco-friendly alternative to peat moss. It is mainly used to improve soil aeration and drainage. Using it in low quantities is the key because of its exceptional water retention qualities. Coco coir also tends to compact with time.
Pine Bark Fines
Pine bark fines are tiny parts of coniferous trees (spruces, pines, firs, etc.). Their primary function is to improve aeration, drainage, and water retention. They may also help with soil-borne disease and provide nutrients.
Due to their moisture retention, it is best to use them in small amounts. Avoid using them with other such materials like coco coir, peat moss, sphagnum moss, etc.
Biochar is an organic material used for soil amendment. Its primary function is to provide nutrients to the soil and improve nutrient retention from other sources. It also helps improve drainage and aeration to some degree.
As it can increase moisture retention, it is better to use it in small amounts.
Horticultural charcoal has a similar nature to biochar. Its primary purpose is to improve aeration, drainage, and water retention (to some degree). It also has anti-microbial properties, which can help rid toxins and other soil impurities.
Due to its water-retentive nature, using it in a smaller ratio is recommended.
Horticultural sand is used to loosen dense soil. For example, if you use garden soil, you can add sand to make it lighter and drain better. Sand often makes up a large part of succulent or cactus mixes.
However, only using sand as a potting medium will make the water pass too quickly without enriching the roots. Mix sand moderately in a potting medium to improve drainage while making it slightly moisture-retentive.
By now, you might be scratching your head, worrying about how to mix all these ingredients to make the perfect potting mix. Well, here’s how:
Creating Your Own Soil Mix for a ZZ Plant
If you don’t want to take the commercial route, you can make your own soil mix for ZZ plants. Using the description of the most important ingredients and additions mentioned above, you can make a soil mix to help your plant thrive.
Making your mix has some key benefits. For starters, you can control the ratio of ingredients. You can also choose cheaper options and experiment with different mixes to give your plant the best growing advantage. Making your soil mix will also help you become a better gardener.
However, experimenting with different ingredients is not everyone’s cup of tea.
It requires time and patience, and you must be attentive to the changes your plant is going through. If you’re pressed for time, I can recommend a time-tested recipe I often use. Before that, here are some essentials you will need.
- Organic potting mix or general potting soil
- Horticultural sand,
- Peat moss or coco coir,
- Organic compost
- Hand spade
- Gardening gloves
- Measuring cup
- Kitchen scale
- Spray bottle
Here’s a breakdown of each ingredient and how it will help your plant:
- Organic/general potting soil is a relatively well-draining and light medium useful for most houseplants.
- Horticultural sand in the right quantity improves drainage.
- Perlite is essential for making the mix porous, aerated, and well-draining. Without perlite (or alternatives), the potting mix will hold water longer.
- Peat moss or coco coir will help retain moisture just long enough for the proper absorption of the nutrients. It will be lightly added to make its moisture retention bearable for the plant.
- Organic compost in small quantities will provide nutrients to the plant.
Let us now learn the step-by-step process of mixing the ingredients for the best ZZ plant soil:
How to Make the Best Soil Mix for a ZZ Plant?
- Weigh the total mix you’d need to fill the pot, and then measure and add each ingredient in the said ratio.
- You should add two parts potting mix, one part sand, one part perlite, a quarter part coco coir/peat moss, and a quarter part organic compost.
- For example, if the total weight of the soil in the pot is around 4 lb, you should measure 2 lb potting mix, 1 lb horticultural sand, ¼ lb coco coir, and ¼ lb organic compost, and mix them.
- Before mixing the ingredients, wear protective gloves. The ZZ plant contains toxic sap that can irritate skin and eyes.
- It is best to mix the soil in a secluded area, preferably somewhere outside, like a yard or a garage.
- Add and mix all the ingredients in the said ratio in the empty pot with the hand shovel. You can lightly spray the ingredients with water to make mixing easier.
- Add a layer of this new mix at the base of a terracotta pot. Lay enough mix at the base that the root ball of the ZZ plant is a couple of inches below the pot’s lip.
- Fill the pot with the remaining mix, ensuring that the plant is stable in the new pot.
- Lightly tamp the soil, ensuring the soil doesn’t become too compact.
Why Does a ZZ Plant Need Well-Draining and Aerated Soil?
The nature of the soil must sync with the plant’s biology to provide the maximum benefit to the plant.
In its natural habitat, the ZZ plant experiences long periods of drought followed by unexpected and intense rains. These conditions have evolved the plant to develop rhizomes. These potato-like structures hold water and help the plant survive until the next shower.
The ideal soil retains moisture long enough for the rhizomes and roots to absorb nutrients and water and drains the rest. If the soil retains moisture any longer, the plant will experience unpleasant circumstances.
Similarly, the plant’s roots mostly experience freely moving oxygen in their natural habitat. They’re not used to struggling for oxygen as the soil in these regions is dry and aerated most of the time.
When you pot a ZZ plant in a dense, heavy, and moisture-retaining medium, the soil becomes soggy, and the roots struggle to access oxygen. A soggy environment also leads to fungal growth and root rot.
As for the pH, acidic soil has different nutrient absorption than the basic soil. The nutrients a ZZ plant needs are best available in acidic to neutral soil (6.0-7.0) instead of alkaline soil.
How to Measure and Amend Soil pH?
The soil pH affects the availability of various nutrients to the plant. If your potting mix has improper pH, your ZZ plant may suffer from nutrient deficiencies. Ideally, the soil pH for a ZZ plant should be between 6.0 and 7.0 (slightly acidic to neutral). You can measure it easily with a soil pH meter.
Amending the Alkaline Soil
If you get a reading of more than 7.0 (alkaline), you can make the soil more acidic by adding ingredients such as compost, peat moss, manure, or other organic substances. However, be careful not to add too much or multiple ingredients at a time. All these additions retain water, and overusing them can lead to the soil staying wet.
Amending the Acidic Soil
Conversely, the soil is too acidic if the meter reads less than 5.5 pH. You can add baking soda (mixed in water), wood ashes, or limestone to fix it. Again, the key is to add small amounts until the soil achieves the desired pH.
Issues Caused by Abrupt Changes and Improper pH
Changing soil pH too abruptly can also lead to other issues. For example, if soil suddenly becomes too acidic (<5.5 pH), the plant may experience Phosphorus deficiency. The soil may also experience an increase in Calcium, Magnesium, Manganese, and Aluminium, all of which can make the plant sick (if present in surplus).
Overly alkaline soil (>7.0 pH) will experience different issues like restricted absorption of Copper, Manganese, Boron, and Zinc—or Sodium toxicity.
In short, each plant needs specific nutrients in a specific amount, and the right soil pH makes that possible.
Signs of Soil Issues in ZZ Plants
A ZZ plant is much more vulnerable to overwatering than underwatering. Therefore, any soil that retains moisture and doesn’t dry out quickly will lead to serious issues for the plant.
Here are some key symptoms if the soil is retaining too much water. Frequently watering the plant can also cause these issues, so make sure to water the plant only when the soil is dry from top to bottom.
- Yellowing or browning leaves
- Wilting leaves and stems
- Dropping leaves
- Mushy spots on stems and leaves
- A foul odor coming from the soil line
- Root rot (only noticeable after checking the roots)
You can also mistakenly pot your plant in a mix that dries out too quickly or doesn’t hold water long enough. Luckily, the ZZ plant can put up a good fight against underwatering. Here are some key symptoms of an underwatered ZZ plant.
- Dry leaf tips
- Leaves dropping off one by one
- Shriveled petioles
The pot goes hand in hand with the soil. Here are some things to keep in mind when choosing a pot for a ZZ plant
Choose a pot made with a porous material like terracotta. It will help the soil dry out faster and reduce the possibility of overwatering-related issues. The pot should also have 2-3 drainage holes.
The pot size is also important as a ZZ plant can become root-bound with time. Always choose a pot with enough space for the air, roots, and rhizomes to move and grow freely.
It is a good practice to take the plant out of its pot every couple of years to see if it has become root-bound. If it has, plant it in a one-size bigger pot.
Should You Use All-Purpose Soil for a ZZ Plant?
All-purpose soil can be a good alternative if you can’t make your mix or find the one I recommended.
A high-quality all-purpose mix will generally contain many ingredients that make the medium well-draining. Even though the ratio of these ingredients will be lower, you can fix it by adding some perlite or pumice to the soil. However, wait and see how the plant is adjusting to the mix before making any changes.
Should You Use Succulent/Cactus Soil for A ZZ Plant?
Since succulents grow in the desert, they have similar characteristics to ZZ plants. However, a ZZ plant requires a bit more water than a succulent/cactus.
Succulent soil is exceptionally well-draining because of a higher concentration of sand and amendments like perlite. However, the sand is in a much greater quantity than a ZZ plant’s liking.
If you want to use a succulent mix for a ZZ plant, you’ll need to add it as an ingredient rather than the base medium. For example, you can mix one part cactus soil with three parts potting soil. By adding cactus soil, you likely won’t need other ingredients to improve drainage and aeration.
But if the soil still retains water, you can add half part perlite to the mix.
There are only a few things to remember if you want to make (or purchase) the best soil for a ZZ plant. Firstly, the mix should have good aeration and draining qualities, complemented by a little bit of moisture and nutrient retention.
Making a custom mix does not have to be difficult, either. If you don’t have a lot of time, simply mix two parts potting mix, one part sand, and one part perlite. Add peat moss and organic compost in a small ratio for better nutrition and moisture retention.
When purchasing a commercial mix, read the ingredients and choose a product that leans towards being well-draining and aerated. But if you love to experiment, refer to this guide to read about different ingredients and their role in the soil.
1.What is the best soil mix for a ZZ plant?
Choose a light and well-draining soil mix that can retain moisture to a smaller degree.
If you’re making your own mix, you can add two parts potting soil, one part sand, one part perlite, and a quarter part peat moss. If you want to purchase a commercial mix, here’s a recommendation.
2.Can a ZZ plant survive in succulent/cactus soil?
Succulent/cactus soil alone contains too much sand to help your ZZ plant grow. However, it does contain other elements like perlite/pumice that are helpful to a ZZ plant. Therefore, you can make a mix by adding one part succulent soil to 3 parts potting soil.
3.How to make soil lighter and well-draining for a ZZ plant?
To make the soil lighter and well-draining, amend it with perlite, pumice, vermiculite, etc. Generally, perlite is the best option as it not only helps aerate the soil but doesn’t retain as much water as pumice or vermiculite. It is also cheaper and easily available in most online and physical stores.
4.What are some types of soil to avoid for a ZZ plant?
Generally, avoid soils that are too dense or too light. For example, garden or clay-based soil is too heavy and retains too much moisture. They are also prone to compaction. On the other hand, using sand alone as a potting medium will drain the water too quickly before the plant can be fully hydrated.