How To Use Perlite For Plants?

Published on:
June 20, 2023

The characteristic that sets perlite different from other volcanic glasses is that it expands from four to twenty times its original volume when heated to a sufficient point in its softening range. Perlite enhances clay soil's texture while accelerating germination and roots, improving aeration, drainage, and insulation in potting mixes.

A siliceous rock that occurs naturally is known as perlite. It may swell from four to twenty times its original volume when heated. This is caused by the water in the perlite rapidly expanding, which is how the very light perlite for gardening is made.

Gardeners mostly use perlite to enhance compost blends and assist with water retention and aeration.

The globe over, perlite is expanded and mined. According to estimates, crude and expanded perlite are both produced and used mainly in the United States.  Other nations that produce perlite, nevertheless, include China, Greece, Mexico, Japan, Hungary, Armenia, Italy, and Japan.  

Benefits of Perlite for Plants

  • stops compaction 
  • greater improvement in aeration and drainage than vermiculite 
  • does not break down 
  • free of weeds, parasites, and diseases 
  • encourages the start of roots and strong growth 
  • holds moisture without getting mushy 
  • pH is almost neutral. 
  • minimizes temperature changes by insulating 
  • sterile, inert, and inorganic 
  • No recognized toxicity or fire risk 

In the further read, we dwell on how to use perlite for plants and additional information on it. 

How to Use Perlite for Plants

1. Seedling blooming

Perlite promotes seedling development and hastens germination.   

Seeds should be sown on a well-watered combination of perlite and sphagnum moss peat in equal amounts. Alternately, mix 2 parts of ready-mixed potting compost with 1 part perlite. 

Keep moist at all times by periodic misting or capillary irrigation for pure usage.  After planting, cover seeds with glass or plastic, sprinkle them with a thin coating of fine peat to preserve moisture until germination and then feed them.

2. Potting Composts

In potting compost mixtures, perlite is used to enhance aeration, drainage, and insulation.  The structure of ready-mixed loam or peat-based composts can be opened up with perlite.

Use 3 or 4 parts Sphagnum Moss Peat to 1 part perlite (80/20) for soilless compost blends.

Use sterilized loam, peat, and perlite in an identical ratio (1:1:1) together with limestone and nutrients for loam-based compost mixes. An alternative is to use a 1:2:1 mixture. Mix well, then after planting, water well and feed as necessary.

3. Cuttings and Rooting

Perlite facilitates uprooting, lowers the chance of damping off, offers the ideal amount of air and water, and almost eliminates water logging. Additionally, it lessens the effects of transplanting root damage and growth interruption.

Use a 50/50 combination of perlite and sphagnum moss peat for cuttings with delicate stems and leaves.   Increase the perlite-to-peat ratio up to 4 parts perlite to 1 part peat (80/20) for tougher cuttings and delicate plants.

Perlite can be utilized entirely for mist irrigation in situations when sterility is crucial. Water regularly, but watch for free drainage. Feed plants as soon as their roots start to grow.

4. Conditioning the soil

By enhancing aeration and drainage, perlite enhances the texture of heavy silt or clay soils. Additionally, it lessens the propensity to "cap" the germination of seeds. These enhancements will be around for a long time. 

Use up to 25% perlite worked into the top 5–10 cm of challenging seedbeds and flower beds before planting. 

Mix perlite with the soil before backfilling the planting hole for trees, shrubs, and roses to encourage root development.  

5. Grass dressing

Perlite will help the air-moisture balance and ensure greater root development and grass growth since it increases aeration and drainage. Perlite-treated golf course greens will be more resilient and tolerant of use in both wet and dry harsh weather situations.

Use the following for establishing new turf or compacted and poorly drained areas on old turf: Spread a thin layer (2–5 mm) of damp perlite that has already been fertilized with the appropriate fertilizer over the afflicted region by spiking it with a hollow tine.  Brush or rake evenly, then thoroughly water.  Remember that a 100-liter bag of perlite would typically cover 50 square meters with a 2mm layer.

6. Hydroponics, capillary watering, and NFT

The inert, sterile, neutral, ultra-lightweight aggregate known as perlite has a very high ability to contain both air and water.  Perlite should be treated with any proprietary chemical sterilizer, steam, flame, or flame gun to sterilize it for reuse.   

Perlite should be used in place of sand or gravel at least 25mm (1 inch) deep on polythene-lined benches or appropriate trays for capillary watering.  

Use perlite in a trench or channel that is coated with polythene, then saturate it with nutrient solution to grow tomatoes in rings and at a cheap cost for commercial output. 

What benefits does perlite have for soil?

Perlite, a component of soil amendment, can assist in resolving a number of growing problems for both indoor and outdoor plants. The perlite soil medium is airy, light, and has good drainage. This kind of soil aids in the prevention of developing troubles such as root rot, fungus problems, and bacterial infections.

The following list of soil problems that perlite can help with or simply perlite uses:

  • Perlite makes it easier for roots to expand.
  • Because perlite insulates the soil from temperature changes, it avoids plant stress.
  • Perlite doesn't lose its quality.
  • Heavy clay soil is loosened using perlite to avoid water collecting on the surface.
  • Any type of soil may be made more aerated with perlite, which also helps roots acquire enough nutrients and oxygen.
  • For pots, patio plants, window boxes, and decorative containers, perlite is the perfect soil material.

How to garden with perlite?

When trying to enhance the soil quality in your lawn, perlite is affordable and simple to utilize, especially if you have drainage problems. For instance, if the majority of the soil in your garden is clay, puddles may form or too much moisture will remain in the soil. In addition to improving drainage, adding perlite to garden soil also promotes stronger plant root growth.

Beneficial worms and insects may maintain healthy and rich soil with the help of perlite soil amendment.

Which perlite type should you use in your garden?

The white, Styrofoam-like balls that makeup perlite are available in three grades: coarse, medium, and fine. For your garden or containers, you should select the appropriate type of perlite based on how much soil modification is required.

Let's examine the three varieties of perlite available in garden centers and shops:

  • The greatest kind of perlite is coarse, which works well in thick, compacted soil. This type of perlite may be used as a soilless growth medium for plants like succulents and orchids.
  • Medium perlite—Potted plants and other containers are the most typical applications for medium-grade perlite.
  • When starting seeds or allowing cuttings to root, use fine perlite. It could be challenging to locate bags of this kind of perlite in supermarkets, though.

Perlite for Plants FAQs

1. Perlite: Is it organic?

As a completely natural substance and not a manufactured one, perlite is safe to use in organic gardening. Perlite is among the materials permitted for use in organic farming, according to the United States Department of Agriculture (USDA). Perlite production does not entail any chemical processing.

2. Can plants be grown in perlite alone?

Plants may be grown without soil using perlite. Perlite, a soilless growth medium, helps the roots receive oxygen while simultaneously holding back some moisture. Perlite may not be the best choice for many plants, though, as it has a tendency to float in excess moisture. Mix perlite and peat moss if you want to use it as a soilless growth medium.

3. Is perlite bad for you?

Silica, which is also the primary ingredient in sand, is a major component of perlite and is not poisonous. Granules of perlite are safe to handle while planting or replanting plants. In both building and agriculture, perlite is used extensively.

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