Are all dirts – or soils – made the same? As a horticulturist, I get asked this question a lot: What’s the best soil for my Monstera, Philodendron, Peace Lily, or [insert your houseplant here!]?
I love this question because, yes, different plants need different types of soil, and it shows that while plant owners may not always know the answer, they know soil is an important factor. Instead of blanket-answering with vague soil types, let’s run through what we at Willow call the Four Core Soil Types. (Yes, I capitalised those to make them Look Important).
In the Willow app, it’s important to make sure you set the right soil type in each plant’s profile. This is especially relevant for those of you with Sensors as the soil type will be factored into Sensor readings.
The Four Core Soil Types are listed in the plant profile like this:
Let’s run through each soil type, how to distinguish between the different types and which plants are best suited for them.
Standard Potting Mix
Standard potting mix is a broad term that commonly refers to any soil that contains actual dirt. It’s usually sold under the name “premium potting mix” or “potting mix” and it often contains fertiliser, organic material and dark soil. It doesn’t have any large chunks through it and often lacks drainage or aeration.
Standard potting mix is most commonly found in pot plants you buy from a local nursery and hardware stores and is known as the default potting mix for all plants. It’s not perfect, but it gets the job done.
The best way to spot standard potting mix is by touch. It should be dense and gritty with no large particles, and it will often clump together when it’s dry.
Plants best suited to standard potting mix
- Herbs and flowering plants like Chrysanthemums and Basil that need to stay constantly moist
- Fruit trees and shrubs like Lemon Trees and Copperleaf plants, which are used to growing in the ground
- Palm trees like the Kentia Palm that aren’t really fussy about soil.
Finer Mix
True to its name, a finer mix is soft and delicate in texture. It’s usually made of thin ingredients such as peat moss, sphagnum moss or coconut fibres.
Finer mixes are usually designed to hold onto moisture for as long as possible. When dry, the mix becomes very loose and dusty but once thoroughly wet it turns dense and compressed.
Finer mixes are commonly seen when growing seedlings or cuttings, especially in commercial plant nurseries. You’ll often see them as a base medium for propagation.
The best way to spot finer mixes is with your eyes. They are often fibrous, stringy and quite damp. When dry, the mix resembles a powder.
Plants best suited to finer mix
- Ferns like the Rabbits Foot Fern and Maidenhair Fern that need to stay constantly moist
- Begonia, which love soft, moist soil for their fine roots
- Tropical species like the Alocasia and Calathea.
Coarse Mix
My personal favourite of the soil mixes and for good reason! Coarse mixes are excellent for indoor plants because they provide excellent drainage and hold onto the essential moisture needed to save your plants the painful experience of being watered too often. It dries out quickly, meaning you can feed your plants often without having to worry about too much water.
Best of all, it’s loose and airy so it allows thick root systems to grow smoothly through it. Without the worries of root rot, your tropical plant species and many other plants who enjoy drainage will love a coarse mix.
Spotting a coarse mix is easy. Look for large chunks of bark, perlite and other large particles. The more the merrier in this case as coarse mixes almost never have any actual soil in them, so the coarse chunks make up the base of this mix.
Plants best suited to a coarse mix
- Tropical Plants such as Monstera and Philodendron, their thick roots grow through coarse mix extremely well
- Plants that are sensitive to too much water like Bromeliads, Devils Ivy and Dieffenbachia
Sandy Mix
Last but certainly not least, we’ve got the sandy mix. The composition is somewhat self-explanatory, but it’s important to note that sandy mixes are different to your classic white beach sand and are more nuanced.
When horticulturists refer to a sandy mix, they’re referring to a mix that’s gritty, granular and dense while maintaining really good drainage. A perfect example of this is gravel or coarse river sand. Both these substrates resemble sand in texture but they drain water really well.
Best way to spot a sandy mix is through touch. You’ll instantly feel the granular texture with a dusty finish. It’s coarser than beach sand but fine enough that it can still fall through your fingers.
Plants best suited to a sandy mix
- Cacti and desert plants which usually grow in sandy, hot and dry climates
- Succulents and plants which don’t need a whole lot of water
I know that when I first started my houseplant journey, I assumed you could plant any old plant into any old pot filled with any old dirt. Boy was I wrong, and I definitely found out the hard way!
Hopefully this read saves you a little bit of time figuring out which soil is best for you and your favourite houseplants and helps you get the best out of them!