by Plant Circle

Plant care: Potting mix

Many longtime plant parents started out thinking that dirt is dirt, and plants will grow in anything. No? Was that just us? Well, luckily thanks to information being more widely available, we now know that plants in fact need high quality potting mixes to really thrive, and to make understanding the ingredients and compositions easier for you, we've gathered them here! Having a good quality potting mix tailored to the needs of the plant is every bit as important as providing your plant with water or sufficient light. In fact, most common plant related issues, like overwatering and root rot, come from using an average quality potting mix... or worse.Let's start by getting into the two most frequently used terms when it comes to this topic: 'potting soil' and 'potting mix'. Though these terms are used interchangeably, there is a difference. Potting soil may contain soil, while potting mix is strictly a soilless medium. Technically, potting soil is nothing but dirt that no longer has the adequate elements necessary to support the growth of potted plants, or indoor plants. Potting mix, however, is sterile, which makes it safer for plants because it's guaranteed to not contain pathogens such as fungus or other diseases. Why is having a good quality potting mix so important? The main reason is that potting mixes are designed to not get too compacted, something that can suffocate the roots of a plant, or impede the flow of water and nutrients, and in the worst cases, cause root rot. A high quality potting mix will be lightweight and fluffy, with the ability to hold moisture. For the roots to grow deeply, good aeration is necessary and recommended. Aeration requires puncturing the soil with tiny holes in order for the water, air, and nutrients to penetrate the roots. To achieve that effect without the physical labour, you simply add bark to the potting mix, which creates little air pockets! Now that we've established the importance of a good potting mix, and what it does for the health of your plant, let's get into the the most common components that can be added to your potting mix! Perlite. Perlite is the name of a naturally occurring mineral. In nature, it exists as a type of volcanic glass, created when the volcanic obsidian glass gets saturated with water over a long period of time. And since fertile, volcanic areas have been settled due to fertile soils since biblical times, humans have been aware of perlite at least since Third Century BC. Other uses of perlite include masonry construction, cement, gypsum plasters, and loose-fill insulation. Horticultural perlite is made by exposing perlite to heat, which causes the trace water contained in the perlite to expand, 'popping' the perlite like popcorn and expanding it to 13 times its former size, resulting in an incredibly lightweight material! Since it is a naturally occurring, mined mineral, perlite is a nonrenewable resource. Perlite is an excellent potting mix additive, and is also an effective rooting medium. Please note: Perlite dust can aggravate existing respiratory conditions and cause eye irritation. Eye and mouth protection are recommended to prevent the dust from being ingested. Want to go deeper? Read an exhaustive article on perlite here! Vermiculite. Vermiculite is the name of a group of hydrated laminar minerals (aluminum-iron magnesium silicates) which look like mica. Horticultural vermiculite is processed with massive heat that expands it into accordion shaped pellets composed of multiple layers of thin plates. It will not rot, deteriorate, or mold, and is enduring, odorless, non-toxic, and sterile. It is however not a renewable source. Just as perlite, vermiculite is an excellent potting mix additive, and can also be used as rooting medium! This article further explores the topic of vermiculite! Activated charcoal. Activated charcoal prolongs the life of soil media by balancing pH levels and sweetening the soil of potted plants and terrariums. It also eliminates odour, absorbs salt residue, and breaks down the build-up of bacteria. We love to add activated charcoal to any potting mix, and we also add it to the water when rooting a plant! Coconut Coir. Firstly, what exactly is coconut coir? Actually everything in between the shell and the outer coating of the coconut seed is considered coco coir! While most people mainly think of the edible parts when they think of this fruit, coconuts actually have many applications in horticulture! Coco coir is known to be one of the most moisture retaining growing medias, and can absorb up to 10 times its weight in water. On the market coco coir is available in three forms: coco peat, coco fibres, and coco chips. It's very common to grow tropical plants in coco coir in Asia; in fact, that's how most of our imported plants arrive from there. We are however not big fans of coco coir as the only potting medium, and therefore suggest using it in potting mixes in combination with other ingredients. For example, you can use coco chips instead of bark, or coco peat instead of peat moss! Bark. We love bark! Namely pine bark shreds. You can easily improve drainage and aeration of your potting mix by adding some bark to it. We recommend it for pretty much all mixes, besides succulent ones. Sand. Sand is super helpful when creating a potting mix for succulents and cacti, as it it increases drainage ability. Please note: we advice not using sand taken directly from the beach, as this type of sand has a high salt content, and could severely damage your plants roots! Ideally you should only use horticultural sand. Worm humus. Worm humus, also known as vermicast, is the final product of decomposed material excreted by the king of the soil: the mighty earthworm! Packed with water soluble nutrients and bacteria, worm humus is a very nutritious organic fertilizer, and excellent all-round soil improver. Worm humus is perfect for refreshing a potting mix, or adding to substrate mixtures already in use. The ideal proportions to aim for are a blend of 10 – 15% worm humus to 85 – 90% substrate. Spaghnum moss. Spaghnum moss is generally used more for cuttings and propagations, however, some Anthuriums can be grown in it, but this is generally only recommended for people who check on their plants daily, as spaghnum moss can dry out quickly, and might require you to check on your plants every day. Read more about this, and other types of moss, in our post dedicated to Anthuriums! Last but not least, and maybe this goes without saying, but don't plant your plant into a pot without drainage holes! Leave it in the plastic nursery pot, and always check for excess water to get rid of after watering. You'll also want your ceramic planter to be a tad bigger than your plastic nursery pot, as the little gap between the two will allow a better airflow around the roots. We hope this gave you an idea of how to provide your plant with the best potting mix, and if you're still in doubt, we recommend starting out with our handmade Aroid Potting Mix! It's suitable for most tropical house plants, and contains a high quality ingredients such as bark, perlite and activated charcoal.Happy potting, plant lovers!