Landscaping: What’s the Best Soil Conditioner for Your Garden?

Is this the year you get serious about improving your soil? There are good reasons to put in the work. Adding a soil conditioner can make garden soil lighter, fluffier, more fertile, and generally attractive to both plant root systems and earthworms, who will work for free to aerate and fertilize the landscape (with their castings).

OK, you’re on board. Now you have to decide which soil conditioner to use. We recently took a close look at biochar and it’s no secret we’re long-time admirers of using compost tea to improve the soil. Today, though, we’ll compare the benefits of coconut coir and sphagnum peat moss—two amendments which are affordable and widely available. Read on to learn which is the right choice for your garden:

Coconut Coir

Pros: Coir, made from the fibers and shell of coconuts, is basically a waste product of harvested coconuts.  It’s a popular hydroponic growing medium because it deters certain diseases, has water retention capabilities, and supports root structures. Coir pH usually runs neutral (in a range of from 6 to 6.7), so adding it will basically keep the soil pH the same. Coir also wets more easily than peat, decomposes more slowly, and withstands compression better than peat.

Cons: Grown in ocean climates, coir can be high in salts. It’s a good idea to wash it to remove excess salinity before adding it to the soil. Also, coir does not contain microorganisms, or trace elements which can enrich soil. And it it comes from tropical regions (most coconut fiber is grown in Sri Lanka or India), the fossil fuel cost to deliver it to the United States is high.

Sphagnum Peat Moss

Pros: When leaves and other plant parts decompose in wetland bogs, peat is formed. Peat lightens soil, aids in breaking up heavy clay, and holds water in sandy soils. It is also great for acidifying soil for acid-loving plants including azaleas, rhododendrons, and camellias. Peat, which can be harvested in the US,  also contains beneficial microorganisms.

Cons: Sphagnum peat moss, which is dead and decayed, needs to be moistened evenly (and kept moist) for best plant growth and health. The biggest negative factor is that peat is harvested from hundred (possibly thousand) year old bogs and is not being harvested at sustainable rates. It takes many years for dead plant material to pile on dead plant material to create a bog. While are efforts made to restore peat bogs after peat mining, there is a question as to whether the peat bogs will restore themselves to their pre-mining state and how long the process takes.

The Winner?

While both coir and peat moss have positive and negative qualities, coir comes out slightly ahead because it is renewable and peat unfortunately (as of yet) is not.

You can purchase coir in ready to use bales and also in compressed brick  that expand quite dramatically when moistened. Blend coir into garden beds or potting mixes to lighten them. Depending on where purchased, the price of coir is comparable to peat.

See more soil basics:

• Dirty Secrets: 10 Ways to Improve Garden Soil
• Your First Garden: What You Need to Know About Topsoil
• The Garden Decoder: What Does ‘Organic Gardening’ Really Mean?