The best potting soil

Which potting soil is best?

Potting soil, or potting mix, is a substrate that usually consists of garden soil, organic matter and minerals. Its purpose is to help potted plants such as vegetables, flowers or herbs grow by providing a healthy, nutrient-rich environment for them. There are several types of potting soil, each with its balance of nutrients and ingredients. Most work well for indoor and outdoor plants. The best one is the FoxFarm Ocean Forest Potting Soil Mix.

What to know before you buy potting soil

Potting soil vs. garden soil

Garden soil and potting soil differ in the following ways:

• Garden soil: This is a combination of organic matter and regular topsoil. It can help with water retention, especially in sandy environments. It also helps make heavy or clay-based soil less compact, which lets roots grow more easily. It's usually inexpensive and works well on plants in the ground outside. One downside is that it contains microbes, which could lead to plant disease.
• Potting soil: Most potting mixes don't contain real soil. Instead, they're usually a combination of things such as peat moss, compost or organic matter. They usually offer better drainage, which is great for potted plants that might otherwise drown. They're ideal for growing plants in a pot, whether they're inside or outside.

Purpose and advantages

Potting soil is specifically formulated to help potted plants grow either indoors or outdoors. The advantages of using it include:

• Helps plant growth: Most mixes contain nutrients that aid in healthy plant growth. They’re also usually better at retaining the moisture plant roots need.
• Prevents soil compaction: High-quality mixes are less likely to become compact than garden soil. This is important as soil compaction can prevent essential resources such as water or oxygen from reaching the plant roots. This could lead to root damage and keep plants from growing.
• Reduces the risk of plant disease: Since it’s carefully formulated, potting mixes can lower the chance of plant disease. Sterile mixes are especially useful when growing seeds.

Types

There are several types of potting soil, including:

• All-purpose: These mixes are good for most indoor and outdoor potted plants. They’re a good choice for new or casual gardeners.
• Sterile or seed starting: With fewer nutrients than most potting soils, this type is ideal for growing seeds or immature plants because it keeps the growing environment sterile.
• Outdoor: Useful for both indoor and outdoor plants, this type often contains fertilizer and pellets that retain moisture.
• Moisture Control: This type relies primarily on pellets that trap moisture until the plant needs it. It’s best for plants that need smaller amounts of water over time.
• Organic: Consisting of organic matter such as compost, bones and decayed plants, these soils are nutrient-rich and fertile. They’re great for less hardy plants.

Plant-specific potting mixes also exist, such as:

• Orchid mixes
• Succulent mixes
• Cactus mixes

These specialty types come with specific nutrients and components that make growing these plants easier.

What to look for in quality potting soil

Formula

Since there are so many types of potting soil, the formulas used vary widely, as do the ratios of each component. Most mixes have some combination of the following:

• Peat moss: Found in most mixes, peat moss is partially decomposed matter that can retain moisture and break up compact soil.
• Animal or plant compost: This helps to fertilize the soil and give the plant the nutrients it needs.
• Coconut coir: An alternative to peat moss, coconut coir serves the same purpose. It’s more environmentally friendly.
• Perlite: A common inorganic material that helps aerate the soil, perlite works well with plants that prefer high humidity.
• Pine bark: Although it has no nutrients, mixes that use pine bark and peat moss offer more aeration and water retention than others.
• Sand: Sand helps with drainage and is great for succulents and cactuses.
• Pumice or vermiculite: These materials are great for water retention and soil aeration. Vermiculite can also hold fertilizer and nutrients.

Other common organic components include bat guano, earthworm castings, bone meal and seaweed meal. These all help provide essential nutrients to growing plants.

Some potting mixes contain agents or specific microbes that help improve water retention. Others have additives such as slime that help balance the pH levels to ensure healthy growth.

Density

The weight and density of potting soil depend on the formula used. For example, fillers such as mulch, sand or topsoil can cause the mix to become very dense. The advantage is that heavier soil is usually nutrient-rich and retains moisture well. The disadvantage is that it can become compacted easily, which could stunt a plant’s growth or cause roots to rot.

If your plants are struggling, consider replacing the potting mix. This can break up any compaction and let oxygen, water and nutrients reach the plant roots.

Longevity

Potting soil can go bad since most of the components eventually decompose. When this happens, it can cause mold or viruses to appear. It can also reduce the nutrients in the soil. These things can result in plant disease and death.

An opened bag of potting mix lasts around 6 months, on average. Unopened bags last one to two years when stored in a cool, dry place.

If you have an older bag, it could still be usable. Check if it smells bad, though. If it does, lay it out beneath the sun so it can dry out any potential germs, mold or viruses. Doing this can also kill off any fungus gnats that have made the moist soil their home. You can also improve the quality of the soil by adding bone meal, compost or fertilizer to it.

How much you can expect to spend on potting soil

The cost of a bag depends on the size and ingredients used. Most cost $5-$35.

Potting soil FAQ

Can you use it in the garden?

A. Although you can use potting soil in raised beds, it can quickly become expensive if you have to use it for large outdoor gardens. Consider using garden soil instead.

Can I make potting soil?

A. Yes, but you need the right ingredients for whatever it is you’re growing. One popular recipe is a 50/50 ratio of peat moss and perlite. Be sure to thoroughly mix it before applying.

What’s the best potting soil to buy?

Top potting soil

FoxFarm Ocean Forest Potting Soil Mix

What you need to know: This lightweight, all-purpose mix is perfect for indoor and outdoor potted plants.

What you’ll love: Available in one, two and four packs weighing in at 12 quarts each, this mix includes peat moss, bat guano and earthworm castings. It has a pH level between 6.3 and 6.8 and does a great job of keeping plant roots aerated.

What you should consider: Some bags may contain fungus gnats.

Where to buy: Sold by Amazon and Home Depot

Top potting soil for the money

Espoma Organic Potting Soil Mix

What you need to know: This potting mix is ideal for growing indoor and outdoor vegetables, flowers and herbs.

What you’ll love: It contains organic matter, such as earthworm castings, kelp meal, alfalfa meal and humus. It also has perlite to prevent compacted soil.

What you should consider: It has slight difficulty absorbing water.

Where to buy: Sold by Amazon

Worth checking out

Miracle-Gro Potting Mix

What you need to know: This potting mix works well for flowers and vegetables since it supports their root systems.

What you’ll love: Capable of nurturing potted plants for up to six months, this mix is lightweight and easy to use. It comes in a single and double pack.

What you should consider: Some bags may have white fungus or gnats.

Where to buy: Sold by Amazon and Home Depot

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Angela Watson writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.