Before exploring popular perlite alternatives, it’s best to review what perlite is and how it’s used. This will help you pinpoint the best alternative for perlite in your particular setup.
Perlite is a volcanic mineral. When heated, it pops like popcorn and expands to 13 times its original size. The resulting mineral is lightweight and porous. Perlite is often used as a soil amendment because it helps improve drainage and control moisture levels. Some hydroponic systems also use perlite as an effective soilless growing medium.
While perlite offers many benefits, it also has some distinct drawbacks that may cause you to look for a perlite alternative:
- Perlite is very lightweight and therefore floats in water, making it difficult for plants to root properly in hydroponic systems.
- It is a nonrenewable resource that cannot be readily replenished.
- It produces dust that can cause respiratory and eye irritation.
What to Use Instead of Perlite
If you’re interested in eliminating perlite from your garden in favor of a better growing medium, there are several options that you can explore. Some are fairly straightforward replacements, while others require an adjustment to your feeding or watering regimen. Carefully consider the needs of your plants and growing system when you choose your perlite alternative.
Coco coir can help aerate your soil like perlite. However, it responds differently to water, so you’ll want to change your watering and feeding habits if you choose to use coco coir instead of perlite in a soil mixture. Coco coir improves water retention, so you won’t have to water your plants as frequently, while perlite causes the water to drain away.
Used in a hydroponic system, coco coir is far superior to perlite because it more effectively anchors roots. Completely organic, coco coir is a byproduct of the coconut industry. While longer coconut husk fibers are used to make mats, ropes, and baskets, the shorter fibers were previously discarded. These fibers are now used to make growing pots, seed-starting pellets, and soil amendments. Coco coir is therefore an extremely eco-friendly choice compared to nonrenewable perlite.
Coco coir absorbs calcium and magnesium, so you’ll need to add these nutrients to your water when you switch to this media. However, you’ll find that the coir does an excellent job facilitating the absorption of other nutrients for your plants.
Parboiled rice hulls are an effective alternative to perlite because they have many of the same characteristics. Rice hulls are effective at aerating your soil, which is the primary purpose of perlite. These hulls also provide your plants with a rich source of silica, which strengthens the cell walls in plants and makes them more resistant to heat and drought.
In one study, a peat and perlite mixture was compared to a mix of peat and rice hulls when growing pansies and calibrachoa. The results showed that both mixtures ended up with plants of similar heights and stem lengths.
Rice hulls break down over time, but you shouldn’t have to replace this amendment for three to five years. The hulls are more effective at staying in the soil than perlite, which often floats to the top and may wash away.
Rice hulls are otherwise considered a waste product, so using them as a growing medium is an eco-friendly choice that creates a valuable purpose for an item that would otherwise be discarded as a useless byproduct of the rice industry. The process of mining and heating perlite consumes a great deal of energy, while utilizing rice hulls adds nothing to the production process that’s already taking place.
Sharp sand can help aerate your soil like perlite. It helps loosen heavy soil and improve drainage. However, you need to choose the right type of sand, or the results could be disastrous. The best choice for this purpose is silica or quartz sand with grains around 1.5 to 2 millimeters. Avoid sand with a smaller grain because it can cause the soil to compact, which is the opposite of what you’re looking for.
Pine Wood Chips
In 2010, manufacturers at North Carolina State first explored the idea of using pine wood chips as an alternative to perlite. They engineered the wood chips to provide the same particle size as coarse perlite.
These wood chips are effective at increasing aeration, similar to perlite. Since they’re organic in nature, they will decompose over time, adding nutrients to the soil and encouraging beneficial organisms like earthworms as they do so. Pine wood chips are often produced as a byproduct of wood milling. Adding these chips to your soil makes use of something that might otherwise be discarded.
Unfortunately, tree bark absorbs many plant growth regulators, so you’ll need to make appropriate adjustments if you choose this product. Plan to use 25% more growth regulators to get the same results you previously experienced with perlite. Pine wood chips can also cause nitrogen deficiencies in your soil, so you should adjust your fertilization as needed to compensate.
With care and consideration, you can replace perlite effectively with an alternative soil amendment in nearly any type of setup. Proper planning will help you make the necessary adjustments to your watering and feeding schedules. While many of these amendments do need to be replaced over time, this is typically because they decompose naturally, making them eco-friendly, organic options for your garden.