makeups premixed, or mix your
own, using the ingredients that
work best for you.
The traditional houseplant potting soil contains equal parts black loam (good garden soil), peat moss, and perlite. The garden soil is quite heavy and provides a solid base of earth for the plant. Its finer particles (mainly clay) retain nutrients. Peat moss is light and absorbs lots of water, keeping the growing medium moist. The perlite acts as a spacer so that roots can grow freely. It also keeps the soil from compacting and becoming waterlogged. Tip: Dry peat moss sheds cool water. When moistening peat for the first time, use hot water.
Many other materials can replace these three. Coarse sand and vermiculite are two of the most common. Shredded bark and charcoal are used in special instances, as for growing orchids and bromeliads. To replace peat moss, some gardeners use compost, leaf mold (decomposed leaves), or rotted horse manure.