Technology & Science

Peat moss use in gardening unsustainable, says soil expert

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It takes thousands of years for peat bogs to form, but it's being harvested too quickly

If applied regularly and in sufficient amounts, compost or wood chips could provide all the nutrients your plants need, according to soil expert Lee Reich. He recommends investigating alternatives to peat moss. (Lee Reich via Associated Press)

Peat moss has been a great helper for years, especially with seedlings. It's made our potting mixes better able to hold both water and air, so important for confined roots, and it's helped grab onto some nutrients that would have otherwise washed out the bottom of pots.

Out in the garden, peat has been similarly helpful, acidifying the soil for plants that need it.

But it may be time to bid goodbye to peat moss in the garden and in pots, according to New Paltz, N.Y., gardener and soil tester Lee Reich, because the way it's harvested is unsustainable.

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Peat moss comes from bogs, those dank environments home to such unique creatures as insect-eating pitcher plants, red-capped and long-necked sandhill cranes, and large heath butterflies. Peat was formed as plants died and were swallowed up in water to partially decompose. What was left, after thousands of years, was a thick layer of almost pure humus, valuable also for being relatively sterile and relatively stable to further decomposition.

Peat grew very slowly over thousands of years, but it is being rapidly consumed for fuel and gardening. (Lee Reich via Associated Press)

Peat grew very, very slowly, about a yard deep every thousand years.

Now, so much peat moss has been harvested for use in gardens and landscapes that in many places there's not much left. Ninety-five per cent of England's bogs have been lost in the last hundred years, much of it burned for fuel.

A peat bog is a unique ecosystem, valuable in and of itself as well as for purifying water flowing through it. Harvesting peat moss destroys that ecosystem, and the supply will be depleted given the slow regeneration rate.

More sustainable approaches

We can temper, to some degree, the bleakness of the above scenario. Researchers have found ways to reclaim a bog ecosystem if only part of the peat layer has been stripped away.

And much of the Earth's peat remains intact. Canada has over 200 million acres left, or about a quarter of the world's supply.

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On the other hand, peat is not indispensable in the garden and landscape and there other materials that could serve as well.

Compost and leaf mould, for instance, can both be made in your own backyard. Or there's sawdust, shredded bark or wood chips — all renewable resources.

Cocopeat as an alternative

The main contender stepping into peat's shoes is a material called coir dust, or cocopeat. This waste product from the processing of coir, a fibre from coconut husks that finds its way into ropes, baskets, mats, packaging and other products, can now have a useful afterlife making gardens more colourful and productive. Its characteristics and even appearance are very similar to peat moss.

Keep an eye out and ask for products with coir, Reich recommends. It's available, as is peat moss, as part of potting mixes, and also straight-up in a bag or bale.

Neither coir nor the other substitutes for peat moss can necessarily be substituted 1 to 1 for peat; tweaking of potting mixes is needed, he says. Then again, coconuts grow a lot faster than peat.