The Best Soil for Indoor Basil Plants

Porous Material

• The base material in the soil must provide good drainage while providing enough density to support he plant. Basil cannot tolerate soggy soil or soil that dries out too quickly. Garden soil is too dense to provide the basil with these basic needs when grown indoors. Instead, use vermiculite or perlite, available at garden centers. Alternately, course sand also provides proper drainage though it may dry more quickly than vermiculite and similar materials.

Organic Material

• Organic matter provides much of the structure in potting soils. Compost, garden loam and purchased potting soils often supply nutrients, but basil doesn't require a high amount of soil nutrition. Using these soil amendments provides most of the nutrients needed for the first few months of the plant's life. If you use peat moss, fertilize more frequently, as it adds few nutrients to the soil. Use 2 parts organic matter with every 1 part porous material.

Sterilizing

• Insect eggs and disease organisms may be present in loam, soil and compost, unless you use purchased materials sold pre-sterilized. Protect your basil plants from insects and disease by sterilizing the soil prior to use. Spread the material in a roasting pan and bake at 200 F for 30 minutes to kill most organisms. Porous materials and peat moss do not require sterilization, as they are naturally sterile.

Fertilizer

• When using peat moss as organic matter, a fertilizer must be worked into the potting soil prior to planting the basil. Use a slow-release 15-15-15 analysis fertilizer to provide most of the nutrients the basil requires during the first three months of growth. One tsp. of fertilizer is sufficient for a 6-inch diameter pot of the herb. Add 1 tbsp. of dolomitic lime to all soil mixtures to ensure the soil has the proper acidity for healthy basil growth.