The potting soil mix you use probably has more impact on your plant’s long term health than anything else. Whatever you choose, your plant will likely remain in this potting soil mix for 1-2 years so it’s a good idea to make sure you choose a potting mix that matches your plant needs and the conditions you live in. Probably the most common issue we see with potting mixes is the lack of aeration and poor drainage. Most commercial potting mixes have a lot of water retaining elements like peat moss, which results in poor aeration and drainage. Your plants need AIR to reach the root zone to achieve optimal health. Costa Rica is generally very humid and has strong rains, so additional aeration and drainage helps your plants grow healthier roots, which leads to more rapid growth and reduced incidents of root rot or disease.
There are countless recipes for potting soil mixes available online, and I recommend doing a little research to see which best suit your needs.
We see a few mistakes that are commonly made, and so here are a few quick tips on how to improve the aeration and drainage of your potting soil mix.
ADD AGGREGATE TO IMPROVE AERATION AND DRAINAGE
We tend to use perlite for our tropical potting mix and pumice for our cactus and succulent potting mixes. We make our own potting soil mixes from scratch, but even adding perlite (anywhere from 25-35%) to a commercial potting mix will generally improve aeration to the roots of your plants as well as improve drainage. For cactus and succulents we use a mix of 75%-85% inorganic material like perlite, pumice, sand or rocks. Switching to this type of gritty, dry potting mix has produced much better results for our cactus.
DON’T USE MATERIALS THAT DECOMPOSE INTO A MUSHY, ROTTING MESS
It’s ok to use an appropriate amount of organic materials like worm castings or turbinate, but avoid materials that rot over time. Rice husks (granza de aroz) are commonly used as a soil additive in Costa Rica, but we find they tend to turn into a mushy, smelly, rotting mess over time. This can lead to root diseases and pests. As the rice husks decomposes the soil will become more compact and will hold less air. The end result is that plants start to suffer due to poor aeration to the roots and poor drainage. Do yourself a favor and switch to using an aggregate for drainage that does not decompose, like perlite or vermiculite.
We have had similar issues with orchid potting mix that is made of wood chips. It’s another topic too lengthy to discuss here, but if you are interested in orchids I recommend doing a little research into semi hydroponics using leca clay pebbles.
DON’T PACK YOUR SOIL DOWN TOO MUCH
When you are potting, only pack down the soil enough to secure your plant in place and to remove any large air pockets. We secure the plant in place, add soil to the top of the pot and then lightly tap the sides and bottom of the pot so that any large air pockets are removed. This leaves space in the soil for water to pass through and for air to circulate more freely. There is no benefit in packing as much soil as you can into the pot. This actually decreases aeration and drainage.
Hopefully this tip helps! If you are looking for premium soil mixes that already have all the fertilizer, water retention, and aeration, come visit our store. We offer potting mixes and aggregates for all types of plants and climates and are happy to help you find the best solution for your needs.