Can you beat peat?

By dorothy dobbie

Sphagnum peat moss.

From time immemorial, people have been using natural products to sustain and improve their lives, so it is interesting to note that we did not get around to using peat moss in our gardens until the 1960s. Peat moss has been used as a fuel since Roman times and maybe even earlier although its heat producing efficiency is only about one-tenth that of coal.

Over the past few years, controversy has waged about the impact of using peat moss in horticulture because of concern about a negative impact on the environment. However only about 0.4 per cent of the 14 per cent of the world’s supply that is being used for any purpose is used in horticulture, and only 2 per cent of Canada’s reserves are mined commercially and under rules to encourage regeneration.

The real issue for gardeners is whether the product is beneficial, and the obvious answer is yes, but that is a qualified yes.

Peat does retain water, up to 20 times its dry weight; it traps air between its particles improving the tilth of soil, making it more friable and easier to use, especially in heavy, high-clay-content soils, and it adds substance to sandy soils. Peat is well loved by commercial growers as a seed starting medium.

Not all peat is equal. The top layer of a peat bog is lighter in colour, spongy and good for water and air retention. It may contain bits of wood from roots, so is often used in larger containers. The next layer is darker in colour, more decomposed and finer. It is used for seed starting, and in consumer-potting materials sold in bales at garden centres. The lower level is the black material that is often used in the garden mixed with soil and other additives.

There are several negatives about peat. It is acidic, with a pH of 3.5 to 4, and so is usually amended with lime. If you want to use peat to help grow blueberries or azaleas, check to see that it has not been pretreated.

While peat moss will last for a few years in pots as a garden soil amendment, the life span is only about two years, so you are better off using leaves or compost. In containers, especially for indoor plants, it harbours fungus gnats. The remedy to that is to let the plant dry out, but the downside is that rehydration can be a challenge because dry peat repels water, although some suppliers add wetting agents.

Peat can also carry a fungal spore that can infect humans. Sporothrix schenckii can be transmitted as sporotrichosis, which usually infects the skin through some opening or cut and, at its most serious, can result in a lung disease. Wear gloves when working with the product.

Finally, peat used in patio plants has been known as the vector in fires caused by people butting their cigarettes in a dry plant container.

So, what is a gardener to do? Use peat where appropriate. It is a good medium for seed starting and most commercial planters use it in their prepared containers, but know that you will have to fertilize frequently because it

Photo by by Fotokannan.

Coir fibers.

Photo by by Kenpei.

Vermiculite. Perlite.

Straw.

does not contain or retain nutrients, except as is trapped in the water peat holds.

What about coir?

Consider other amendments such as coco husks, also known as coir. Coir also retains water well, up to 10 times its weight by volume, and holds onto it longer than peat. Coir contains no fungal contaminants, deters fungus gnats and doesn’t burn. It has a neutral pH and even contains some trace elements such as manganese, copper, iron, and zinc. For use in containers, it should be mixed with garden soil at 50 to 80 per cent coir with vermiculite, perlite, or coarse sand. A mixture of two parts coir to one part pumice (volcanic rock) makes an idea home for succulents. It breaks down more slowly than peat in the garden.

If you choose coir, buy the bagged product over the bricks which are harder to rehydrate, although both are easier than dry peat.

Both peat and coir come in different textures which can affect their ability to hold water.

Other amendments in the garden

Compost is ideal, of course, but many people simply do not have the time or the patience or maybe the room to compost, so here are some alternatives.

Good old leaves from the lawn are a perfect treat for garden soils. Chop them up with your lawn mower and in no time at all, the earthworms and other microbes in the soil will incorporate them into their world, feeding plants and keeping the soil alive and healthy. Chopped leaves retain water and air, lightening soil texture. You can add them in fall or store them in paper bags. Add grass clippings to provide nitrogen and help with the decomposition. Adding water will help with decomposition.

Leaves and leaf mould will restore nitrogen, phosphorous, potassium and trace elements to garden soil.

Wood chips and bark also break down over time and add organic life to garden soil.

Perlite, which is puffed up volcanic rock, is inexpensive and often used in planters. Each tiny particle is filled with air pockets that retain both air and water.

Vermiculite, another container soil amender, is made from super heated aluminum-iron magnesium silicates. It is sterile but due to its accordion shape is even better at retaining water than perlite, though not as good aeration. It fell out of favour when it was learned that it could contain small amounts of asbestos, however, it is still available.

Newsprint is often used by vegetable gardeners to deter weeds between rows. If shredded, it breaks down eventually and adds useful organics to the soil.

Bagged manures, straw, sawdust and wood ash are a few other choices.

The key to soil amendments such as these is their ability to hold water and tap air in the soil as well as add organic materials to feed the millions of beneficial microbes and little insects that work to make nutrients available to plant roots. r