Plants have adapted to wildly different environments and, to some extent, you should endeavor to mimic their native soil when deciding what mixture to use. You can also alter a soil mixture depending on where you plan to grow it and to better suit your watering routine. It’s often a daunting task to look at the myriad number of soils and choose the right one for your particular houseplant. To get started, there are a few basic questions to ask yourself:
- What type of plant are you potting?
- Where will your plant be grown?
- What are your watering habits?
Plants can typically be broken down into a few broad categories based on their needs — succulents/cacti, tropicals, ferns/ivies, and specialty plants. Figuring out the category your plant falls into is a good place to start for determining its base soil requirements. Succulents and cacti need a well draining medium which doesn’t hold much moisture and usually includes perlite, coarse sand, or rice hulls. Tropicals typically require a balanced mix that retains good aeration, drainage, and moderate water-holding properties. Ferns and ivies are really a subset of tropicals, but common enough to warrant noting that they benefit greatly from a larger ratio of vermiculite to hold a little extra water. Finally, there are some plants that have very specific needs, and require a mix tailored accordingly. These specialty plants include orchids, African Violets, and carnivorous plants. These general categories will help you pick an appropriate soil base.
After choosing a broad soil type, you should consider other potential amendments by thinking about where you want to put this plant and the conditions of its’ microclimate. First, observe the light level. Plants in bright direct sun may need some extra water retention, with the general exception of cacti and succulents, while plants in a darker environment need better drainage. Next, consider the humidity of the area. Relative humidity can play a role in how quickly a soil mix dries out. Humidity typically warrants a small change, like using vermiculite rather than coco coir in locations like bathrooms or around kitchen sinks. Note: planting in a terrarium may require a drastically different media due to the potentially significant different relative humidity.
Finally, consider your habits and how often you find yourself watering. If you like to give your plants a lot of love and water them often, you may want to increase the drainage of your houseplants with either sand, perlite or possibly bark. If you frequently wait for your plants to start wilting or dry out completely, consider adding something extra to hold a little more moisture in the soil. Some coconut coir and vermiculite will hold extra water to help your plant survive until the next deluge. While all of these ingredients can assist with personal habits, they are by no means a solution to keeping a plant that doesn’t fit with your needs. The goal is to supplement an appropriate mixture, not replace one. Planting a cactus in all compost and coconut coir can only end in disaster. However, adding a small amount of vermiculite to a sandy succulent mix will help that cactus if you forget about it for a month at a time. In general, when adding soil amendments to help with your routine, just be sure that you don’t fundamentally alter the type of soil you are trying to create.