One of the many things that I learned on my trip to Steve Lucas’s Exotic Rainforest atrium was how to simulate rain forest soil. Steve showed me the soil that he makes and uses for all of his tropical plants (primarily Aroids) and explained the natural processes that make a very similar soil in the rain forest.
As far as I know, there aren’t any potting soils available for purchase that are as good as the one listed below. If you like growing tropical plants, try making your own soil mixture – it’s fun and it’s likely to be better than anything you can buy!
Below is the recipe, along with some of my customizations. You can make this great potting mix pretty cheap, if you’re creative.
- Miracle Grow Moisture Control potting soil
- Sphagnum Peat Moss – broken up by hand
- Cedar mulch – only the smallest pieces
- Orchid Bark Mix
- Sphagnum Moss – cut into tiny pieces
The goal of this mix is to provide a highly-organic, quick-draining soil. Many of Steve’s Aroids are epiphytic or semi-epiphytic, which means that they grow on trees in nature and require very little soil. However, in nature their roots are nearly always getting wet. The idea is that the roots don’t need to stay wet long, because another rain will come soon. The tropics are known for their regular rain fall. With the chunks of bark and moss in this soil, the roots make contact with moisture in the soil, but will not be sitting in a wet soil for any period of time.
As with all recipes, there is plenty of room for experimentation.
The first ingredient is a suggested base potting soil. I have purchased a non-name brand potting soil that is a competitor to the Miracle Grow Moisture Control. It is priced a little cheaper and I can’t tell much of a difference, after having bought both of them. Recently I found a really good potting soil at a local nursery (TLC) that includes some additional organic material, including some small pieces of cedar mulch. Naturally, this negates the need for adding cedar mulch separately.
Sphagnum peat moss can be purchased in large blocks. I bought by huge bag about 2 years ago and I’m just now finishing it off. I have potted some plants exclusively in peat moss, but I usually mix it with equal parts of a potting soil. Make sure to break this apart in to small pieces to that it will mix well with the other ingredients.
Cedar mulch or cypress mulch is one of the ingredients that helps with drainage. It loosens up the mix and adds more avenues for water to escape from the soil.
You can purchase a couple of different types of charcoal that are safe to add to your potting soil: aquarium filter charcoal and horticultural charcoal are both safe bets, but can be expensive. The cheaper barbeque charcoal is not safe to add to your potting soil, as there are added ingredients in the processing that can add harmful elements to your soil. I chose the ultra cheap option, which is to gather some charred wood from fire pits. There is still a risk of getting charred wood that has lighter fluid on it, but the lighter fluid is likely to have all burned. I played it safe and used wood from my own fire pit in the backyard, which I knew had never had lighter fluid on it. The charred wood can either be broken apart by hand or with a hammer. It’s a messy job, but we are talking about dirt, here.
In place of perlite, I substituted vermiculite. The two ingredients have different properties, but I already had vermiculite on hand, so that’s what I used. I use vermiculite for rooting cuttings and also for my hypertufa pots. Perlite is much easier to find than vermiculite and can be bought in a number of different sizes. As with all of these ingredients, if you’re planning on messing with plants for the rest of your life, it’s probably cheapest to buy the larger size for the long haul.
When it comes to the bark mix, I guess I am luckier than most. In my backyard there is a huge Sycamore tree and a fairly large Magnolia tree. Both of these trees shed some bark at certain times throughout the year. The Sycamore sheds a lot of bark in the middle of the Summer. Not only do I get free bark for potting soil, but I’m not just raking it up and putting it in cans at the curb. I crumble the bark in to as small of pieces as I can manage and mix it in with everything else. Of course, if you don’t have a bark factory in your backyard, orchid bark mixes are pretty easy to find these days. Just look at your local home and garden/hardware store in the potting soil section or houseplants section.
The last ingredient, Sphagnum Moss, can also be found in this section. It is also used for potting orchids. If you cut the long, stringy pieces into small pieces no longer than 1 inch, it will work its way into the mixture rather well.
I hope you enjoy making your own potting soil. Good growing!