Potting Soil

During the summer months, nothing looks lovelier than hanging flower baskets or overflowing window boxes. Many gardeners also bring potted plants into the home to add touches of green to inside spaces all year round. If you are a container gardener, you probably already realize the importance of good, quality potting soil. In addition to needing water, nutrients and air to grow, plants also need soil that drains well. For garden plants, gravity pulls water through the soil. Containers, however, are too small and shallow for gravity to do its job. For this reason, you need potting soil that provides the appropriate amount of drainage and extra nutrients to help plants thrive. Before you purchase potting soil, consider the following questions:

• Can you use all-purpose soil or do you need a mix for acidic plants?
• Will you need a premium or professional potting soil mix?
• How can you ensure you are buying high-quality potting soil?
• Is it more convenient for you to use a potting soil with fertilizer?
• Do you prefer buying premixed potting soil or mixing your own?

Ingredients, Types and Selection Tips

A potted plant will only be as good as the soil in which it grows. That's why selecting the right potting soil is so important. The key to selecting good soil is understanding the bag's list of ingredients. By changing the quantity of these key ingredients, you can create the perfect growing medium for your garden or houseplants. There are four basic types of premixed potting soils, which vary by function and cost. If you decide to buy potting mixes, rather than mixing your own, there are several selection tips that will help you choose high-quality soil.

Ingredients: The main ingredients in potting soil are sphagnum peat moss, vermiculite or perlite and aged compost products. Sphagnum peat moss is responsible for holding water in the soil. Perlite separates the fibers in the peat moss so the soil is more porous. Vermiculite has the same function but holds more water than perlite. Compost adds nutrients to the soil and the best quality compost is made from aged forest products. Potting mixes are sometimes referred to as "soilless," meaning that they do not contain the type of dirt you would find in your yard or garden.

• Look for better-quality potting mixes, which contain 10% to 15% perlite
• Some potting soils also include lime to balance the pH, if needed
• Some soils contain wetting agents that help retain water to prevent drying out
• Wetting agents are helpful in soil used for plants in hanging baskets and window boxes
• Sand is found in some mixes but doesn't hold water well and can hinder drainage

Types: There are four different types of potting soils, including all purpose, premium, professional and plant specific. The cost of each varies, according to the specific ingredients and the amounts included in the soil. All-purpose potting soil is appropriate for adding ingredients, such as plant food. Premium mixes help augment water drainage and aeration with the addition of perlite and vermiculite. Professional mixes contain materials that are more completely processed and are usually very high quality. Plant-specific soils are premium mixes designed specifically for a certain plant's needs, such as cactus or African violets.

• If you are an amateur gardener, use a premium mix for best results
• Some premium mixes include water-soluble or slow-release fertilizer
• For a small amount of soil, premixed types cost less than mixing your own
• Avoid heavy, low-quality mixes that contain manure, topsoil or muck peat
• For roses, cactus, African violets or orchids, consider a plant-specific soil

Selection Tips: When it comes to potting soil, you usually get what you pay for. Higher prices can often be a good indicator of quality. However, take a look at the list of ingredients on the package and make sure the main ingredients (sphagnum peat moss, vermiculite or perlite and aged compost) are listed. In addition, when it comes to compost, look for a description that reads "aged forest products" as lower-quality mixes can contain yard waste or sewage sludge. Whenever possible, open the bag and look for potting soil that is even in texture. Avoid soil that has large dirt clumps or contains large chunks of wood, bark or other composted materials.

• When comparing potting soil, look for packages featuring a satisfaction guarantee
• Although fertilizer may be listed on the package, plants always need extra fertilizer
• For starting seeds, use a soilless mix for better drainage and water absorption
• For cactus and succulents, make or choose a mix that contains sand
• For container gardening on balconies, choose a lightweight mix without sand

If you prefer to mix your own potting soil, consult the following chart to learn what ingredients and how much of each you will need to create a variety of different mixtures.

Soil Mixing Chart

Acid-Loving Plant Mix --for plants that need acidic soil to grow 4 parts organic matter 1 part sand, perlite or vermiculite All-Purpose Mix - for use with most types of plants 3 parts organic matter, such as peat, humus or sawdust 1 part sand, perlite, vermiculite or a combination of all three 1 part sphagnum peat moss Cactus and Succulent Mix -- for cactus, succulents and other plants requiring good drainage 3 parts organic matter 2 parts sand, perlite or vermiculite Seed Starting Mix -- for starting seeds in flats 1 part sphagnum peat moss 1 part vermiculite Seedling Mix --for seedlings that have developed their first set of leaves 2 parts organic matter 1 part vermiculite 1 part sphagnum peat moss

Features

All-purpose Potting Soil: Premixed soil for potting new houseplants or repotting plants that need larger containers. You can also use all-purpose potting soil for potted vegetables, herbs and outside container gardens.

Potting Soil Plus Fertilizer: Premixed potting soil with a time-release fertilizer feeds plants for several months to promote strong root development. Like general, all-purpose fertilizer, this variety works well for houseplants and garden plants and contains a blend of sphagnum peat moss and perlite. This type of soil works especially well for container plants and hanging baskets.

Seed-Starting Mix: A seed-starting mix is specially formulated for seed germination and growth. This mix also works well for leaf, stem and root cuttings. Containing sphagnum peat moss and higher levels of vermiculite than other mixes, seed-starting mix provides the proper medium for growing seeds and cuttings quickly.

African Violet Potting Mix: African violet potting mix contains lime with a pH adjusted for the acidic type of environment these flowers are accustomed to. The mix also contains a mixture of sphagnum peat moss and perlite for improved soil aeration and drainage for optimal growth.

Cactus Potting Mix: Cactus potting mix works well for cactus and succulents because it contains a special blend of organic materials, sand and perlite to promote drainage. These mixes also contain bone meal for phosphorus to promote blooming and root development.