Houseplants Under Lights

Lesson 2: Houseplant Containers & Potting Media

Potting Media Components -- Part 2

Sand

The only sand suitable for use in potting medias is known as "sharp" or "blasting" sand. Beach sand is much too fine to use. If you want to use sand, go to a local builder's supply store to find the appropriate type of sand.

Advantages: Sand adds weight to the pot for plants that tend to be top-heavy. It also provides both good drainage and good aeration levels for the roots. Disadvantages: Sand must be washed of all silt, clay and organic matter. It is very heavy. Some sources of sand may have too much salt in it for healthy plant growth. Sand provides no nutrients.

Perlite

This is a siliceous volcanic rock that expands into a lightweight particle when heated. It is sometimes available in different sizes.

Advantages: Perlite provides good aeration for root growth. It holds limited water thus enhancing drainage. It doesn't compress in soil. Perlite is totally sterile. Disadvantages: Perlite floats to top of planters (can solve this problem by only using it in media in the lower half of the pot). It holds little fertilizer.

Styrofoam Some nurseries are using styrofoam in their potting mix. They buy bags already pelleted. A home gardener could easily put a handful of styrofoam peanuts into the blender and chop them up. If you have exceptionally large pots (perhaps for a potted tree), you can use a layer of these on the bottom to lighten the pot. If you decide to try this, be sure you use the real styrofoam peanuts and not the ones made to break down in composting.

Advantages: Styrofoam is very inexpensive. It is a recycled product that doesn't break down easily in waste disposal. Disadvantages: It will eventually need to be disposed of; it is not recyclable, and floats to top of potting media after watering.

Pumice

Pumice is a light colored volcanic rock, which is extremely porous. Succulent growers frequently use this in potting medias to create excellent drainage conditions for the plants.

Advantages: Pumice is lightweight, doesn't compress down over time, holds water, provides excellent aeration of the soil so the roots can reach air. Disadvantages: Pumice is very expensive and quite difficult to find in some areas. It is usually not used except for succulents, cacti, and in some cases, bonsai plants.

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