Standard Potting Mixes

The standard base

Use two parts clean, screened potting mix, one part fine pine bark, and one part perlite. This is the starting mix for many foliage houseplants.

Succulents and cacti

Make approximately one-third of the blend screened potting mix and two-thirds coarse mineral material such as pumice, perlite, or grit. For plants especially vulnerable to rot, including winter-hardy outdoor rosettes, the mineral share may be increased to about three-quarters.

Epiphytes

Use two parts fine bark, one part screened potting mix, and one part perlite. The goal is rapid drainage with humid air around the roots.

Outdoor perennials

Use two parts existing loam, one part finished compost, and one part coarse mineral material when drainage needs improvement. Do not create a sharply different pocket inside heavy soil.

Safety and adjustment

Wear a dust mask while handling dry ingredients and moisten them lightly before mixing. Change one factor at a time. A mix is successful only when water drains freely yet roots do not remain chronically dry.

Sources

• Purdue Extension — Container and raised-bed gardening
• University of Maryland Extension — Potting media