Potting Soil

Potting soils serve the vital functions of both stabilizing the plant and being the source of water and nutrient uptake. They may vary in weight and composition, and therefore must be selected according to the desired final use.

Commercial potting soils are usually "soiless," which means no natural topsoil was used in the mix, but rather peat moss, composted barks, drainage materials like perlite, and other nutrients and conditioners to make the media stable. It is a bland soil, so the fertilization can be controlled to benefit the specific crop being grown. It is also sterile, so no weed seed or pathogens are present.

Homemade potting soil uses topsoil as a prime ingredient to introduce natural microorganisms and minor nutrients. It is usually heavier in weight, and is excellent where pots cannot be watered frequently. Container gardens using homemade potting soil still need regular fertilization and can benefit from being sterilized to remove harmful pathogens and weed seed.

To sterilize soil, fill a pan with the damp soil mix, cover with foil, and bake on an outdoor grill. Use an instant read thermometer to confirm the internal soil temperature has reached 1800, and hold there for 30 minutes. Allow to cool before using.

Potting soil ingredients:

• Topsoil - harvested from your garden, precleaned of obvious debris, screened to remove oversized chunks
• Peat moss - medium to fine milled, natural brown, baled
• Compost - from home composting systems, urban compost piles or purchased mushroom compost
• Sharp sand - coarse mason or torpedo sand
• Vemiculite - expanded mica
• Perlite - natural volcanic stone
• Charcoal - horticultural grade, untreated
• Nutrients/Amendments - bone meal, lime (dolomitic lime has manganese), potash, timed release fertilizers, etc.

Recipes

Simple General Mix:

• Equal parts topsoil, peat moss, perlite or vermiculite

General Mix:

• 3 parts peat moss
• 2 parts perlite
• 2 parts soil
• 1 part vermiculite
• 1 part coarse sand
• 1/4 part fine horticultural charcoal
• To 2 gallons of mix add:
• 2 cups bonemeal, 10 tablespoons dolomitic lime, Ferti-lome Start-N-Grow timed release fertilizer (according to package directions)

Cacti Mix:

• 1 part compost
• 3 parts perlite of vermiculite
• 1 part coarse sand
• 1 part fine silt

Seed Starting Mix:

• 14 parts fine peat moss
• 3 parts perlite
• 3 parts vermiculite
• 1 part dolomitic lime
• Ferti-lome Start-N-Grow timed release fertilizer (according to package directions)

For your convenience we offer several premixed soils for various types of plant matter. Please ask a Hoerr Garden Center employee to help you select the correct soil for your needs.