7 Alternatives to Use in Place of Perlite in Soil

Perlite is a useful element in many potting soils and seed-starting mixes. It’s sourced naturally and offers benefits to soil structure and content. However, gardeners are increasingly seeking perlite alternatives. The reasons for this vary, but some are better than perlite in the long run. 

Growers pay more and more attention to how different soil elements are sourced these days, seeking eco-conscious products that come from renewable resources. Organic materials are also important for many gardeners, as using what would naturally occur in soil becomes a focus. 

What are the viable alternatives to perlite? The answer to this question depends on the context. Determine first what aspects of perlite provide the desired outcome. Then seek a different material that offers the same benefit with more advantageous elements included. 

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Perlite’s Role

This superheated volcanic glass adds structure to soil and improves aeration. The surface of each grain of perlite is covered in little cavities that have the capacity to hold water, too, though this is not what it’s chiefly used for. When we look for a replacement for perlite, we seek out something that can do at least one of these things. 

Reliable stand-ins have the ability to improve aeration in the soil, hold water, or add tilth. There are a number of materials that can do at least one of these, and sometimes they should be used in combination with other materials for the full effect. 

Another important role that perlite serves is in its chemically inert nature. It’s a great material to include in seed-starting mixes and in rooting mixes, as it doesn’t have nutrient content that can burn sensitive developing roots. It stands in for a rooting medium, but can still take on molds or algae if it’s not managed properly. 

Why Seek Perlite Alternatives?

One of the main reasons people choose a different material over perlite is that it is technically inorganic, as it’s not something you’d find in soil. It is generally manufactured, rather than harvested in its end form from a natural source.

While its raw state does occur naturally, it is often shipped over the Atlantic Ocean from Greece, making it less eco-friendly than other options that are available more locally.

Gardeners who use soils with lots of perlite might notice it tends to float up over time, displacing its structural ability from within the soil to the soil surface. The dust it produces can also cause problems if inhaled, and it requires hydration before use.

Rice Hulls

Rice hulls are among the viable perlite alternatives. Rice hulls provide the same structural benefits that perlite does, with added micronutrients. When you use these to promote better drainage in your soil, they provide calcium, magnesium, iron, zinc, manganese, and copper as they break down. 

Rice hulls are a byproduct of rice harvesting. Put simply, they are the coatings that are separated from the rice grains before rice is washed, dried, and packaged. Unlike non-renewable perlite, rice hulls are eco-friendly. Using rice hulls is a great way to have the same effects as perlite while using a byproduct. 

Peat Moss or Coco Coir

If you wanted to use perlite for water retention, peat moss or coco coir are better perlite alternatives. While perlite does have some water-holding capacity, it pales in comparison to coir and peat moss. Peat moss, for instance, can hold 70 to 80% of its weight in water. A similar volume by weight is possible with coco coir.

For more eco-conscious options, gardeners often choose coir over peat. Coir is an offset from coconut harvesting, whereas peat comes from bogs. Peat is a non-renewable resource. However, today’s peat-harvesting practices are much more ecologically-sound than those of the past. And shipping coco coir over long distances could render it less eco-friendly. 

The choice is yours here, but for water retention, these are the best perlite alternatives.

Horticultural Sand

Unless you are trying to improve the structure and tilth of clay soil, horticultural sand is another one of those good perlite alternatives. Gardeners use small amounts of this sand to break up the soil structure and improve it. Because sand particles lack nutrients and don’t hold water, it’s better for plants that don’t need a lot of nutrition, but do need fast water drainage. 

Horticultural sand is a variety of crushed rocks and has a different composition than play sand or volcanic sand. It’s best not to use it in clay soils, as sand and clay create a concrete-like mixture when moistened. That’s the last thing most plants need.  

Succulents and cacti thrive in a mixture that includes equal parts potting soil and coarse sand. Other plants appreciate sandier soils, like citrus trees, and do well in a soil mix with horticultural sand as a perlite alternative. But for plants that need rich, acidic soils that hold moisture, other options are preferable.

When you replace perlite with sand, test your soil mix before potting up your plants. Squeeze it in your hand, and if it falls apart slightly, you’re working with a good combination of elements. If it doesn’t fall apart at all, add a little more sand. If it falls apart too much, add more potting soil. 

Manure and Compost

Homemade compost and composted manure are great perlite alternatives, as they improve the structure and content of soils. Both contain macro and micro nutrients that perlite lacks. They encourage microbial life that promotes a soil full of life and nutrient exchange capabilities. 

Incorporating either element as an amendment before planting, and after planting. For established plants, side dress with a compost or well-rotted manure of your choice. As they break down, they infiltrate the soil surface and beef it up too. 

Perlite offers no nutrient content to soils, but compost and manure have a constant provision of nutrients offered to soil over time. 

Pumice

Much like perlite, pumice has pores that hold water. This porous quality also lends drainage to the soil. However, unlike perlite, pumice is heavier. It doesn’t float to the top of a soil mix as it gets watered over time. It stays in place, and it’s a naturally occurring material that doesn’t require manufacturing. 

Pumice is sourced from volcanic eruptions. It’s superheated rock that is ejected from volcanoes. As the rock heats up, pores develop. Because eruptions happen repeatedly, pumice is a reliable, renewable resource (unlike perlite).

Pumice has multiple applications and fits into many functions of a garden space. Perlite, on the other hand, is slightly limited in its scope. Use pumice in cactus mixes, as a rooting medium, an aerator for soil, mulch, or even as a hardscaping material.