Using Sphagnum Peat Moss Responsibly in Your Vertical Garden

Sphagnum Peat Moss

As an aspiring gardener, you’ve researched everything your beloved plants need to grow fruitful and multiple. If you’re adding acid-loving plants to your garden, like camellia or edible nasturtium, you’ve probably found advice suggesting that you add sphagnum peat moss to lower the pH of your soil. If you’ve rushed to the internet to purchase enough sphagnum peat moss to keep all your flowers and veggies happy, you’re probably confused at the variety and even stunned at the cost.

Don’t be. While sphagnum moss is expensive, sphagnum peat moss usually isn’t. Don’t confuse the two, and make sure that you read the descriptions carefully. While sphagnum moss can cost $10 or more for half a pound (you know you’ll need buckets of it for your hydrangeas), you’ll find it’s packaged for crafts, not gardening. So, what is sphagnum peat moss, where do you find it, and even more importantly, should you even be using it?

Sphagnum Peat Moss Versus Sphagnum Moss

Sphagnum moss is a genus of up to 380 different species of mosses. Mosses are plants that reproduce with spores, much like fungi. Unlike true plants, mosses have no vascular system to distribute water and nutrients throughout their structure. And of course, they don’t flower.

Sphagnum moss grows in various countries across the world, generally in damp wetlands with high water tables. Much of the sphagnum moss we see commercially comes from Canada or Michigan, although it also grows in Scotland, Ireland, New Zealand, and even cooler parts of South America.

What is important for gardeners to know is that “sphagnum moss,” as sold commercially in small bags and bricks, is generally the live moss after drying and sterilizing. Many florists use it on plant and flower arrangements. It’s particularly good for adding a bit of “green” where you don’t wish to tend growing live plants.

Why is sphagnum peat moss different?

Sphagnum peat moss, on the other hand, is not live plant material. Nor is it harvested from live plant material. As sphagnum moss dies off in bogs, it sinks and decomposes, very slowly, beneath the live plant matter on top. It may also contain other plant materials blown or washed in from incoming water flows.

Harvesters source these rich layers of decomposed materials for a variety of purposes. They drain the peat bogs and cut the compressed matter out in bricks. After they’ve dried, they ship the peat in blocks to retailers for use in home gardens. Traditionally, many North European countries used peat blocks as an inexpensive source of fuel. In North America, companies have generally harvested and sold it for gardening.

The benefits of sphagnum peat moss for gardeners

Sphagnum peat moss has a very low pH, which makes it an excellent soil amendment for acid-loving plants. It can also help acidify the soil where it’s too alkaline in general for good garden production.

Its structure makes an excellent soil lightener for areas that have lots of clay. For plants that prefer less rich soil, such as succulents, it’s a preferred potting medium. In heavy soils, sphagnum peat moss provides a better texture where delicate plant roots can spread out. It resists compaction, which can make it impossible for plants to deploy the root systems they need to grow. Because of this property, it makes an excellent component for seed-starting mixtures.

It also has excellent water-retention properties, so your plants will stay better hydrated between watering. Many gardeners use it to improve water retention for chronically thirsty plants, like tropical foliage and flowers, and vegetable plants like tomatoes.

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The downsides of using sphagnum peat moss

Before you start adding it to your containers or garden soil, it helps to understand some of the pros and cons associated with sphagnum peat moss.

While sphagnum peat moss improves the structure of your soil, it doesn’t add many nutrients. It may contain some vital micro-organisms that prove beneficial to your soil. However, these micro-organisms vary depending on the geographical source of your peat moss. Unfortunately, that may be impossible to discern from the label and impossible for the distributor to guarantee.

Because of its low pH, it may not be suitable for all of your plants. That is less of a problem if you grow in containers and can sequester your plants by their soil preferences. But if you’re planting spring bulbs like irises, crocuses, hyacinth, and lilies, anything that increases soil acidity will be wasted effort and expense.

Finally, the biggest concern about using sphagnum peat moss in your garden is the environmental impact from its harvest.

Environmental Concerns About Sphagnum Peat Moss

A third of the world’s soil carbon is tied up in peatlands across the planet. During the harvest, it releases carbon dioxide into the atmosphere. CO2 is the prime driver of climate change. And while peat harvests comprise only five percent of human-made carbon dioxide emissions, the less we release, the better for the environment.

Along with releasing these harmful gases, there is controversy over whether or not our peat harvests remain sustainable. Peat bogs develop at an infinitesimal rate, about 1/16th of an inch every year. The peat harvested today has been quietly and slowly developing over hundreds, even thousands, of years. Because of the time involved, experts consider peat moss as an unsustainable resource.

Even after hundreds of years traditionally harvesting and burning peat for fuel, the UK is working on phasing out its use to end it completely by 2030. Even the Royal Horticultural Society has made steps forward, reducing its use of sphagnum peat moss by 97 percent in its gardens.

Several companies in Canada are working to restore any bogs they harvest by allowing them to flood again. They then re-seed them, claiming the moss grows back over the site within five years.

That said, we need to reduce our use of sphagnum peat moss and seek alternatives for improving soil quality.

Alternatives to sphagnum peat moss

If you’re concerned about the expense or environmental impact of using peat moss in your vertical garden, you’ll be happy to know there are many alternatives.


If you have the time and space, composting will help provide many of the benefits of sphagnum peat moss without the ethical concerns. It benefits your plants, reduces waste in the landfill, and even saves you money. While it does take time, space, and the judicious combination of ingredients in specific ratios, cultivating a compost bin or pile is one way to improve your soil quality.

Coconut coir

Many horticulturists advocate for the use of coconut fiber for starting plants and for mixing in with soil for a lighter texture. A byproduct of coconut processing, you may have already seen it at your local garden center. It’s often used in hanging baskets to retain water and corral errant roots.

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Yard waste

You don’t always have to compost your yard waste to gain the benefits from fallen leaves and grass clippings. You can even use finely chipped wood mulch to improve the quality of your soil. Instead of bagging your dead leaves and dried grass clippings and putting them out on the curb, work them into your garden. It helps if you run them through a wood chipper or leaf shredder first. You can even mow them over a few times with your lawnmower. This debris can provide a significant positive impact on poor garden soil.


You’ll find this “puffy rock” material at your local gardening center. Made of volcanic rock matter, the irregularities on the surface of all these tiny pebbles help your soil to retain water while keeping it aerated so that plant roots can spread out and get comfortable.

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Similar to perlite in concept, vermiculite comprises volcanic glass that has been superheated. It looks like Styrofoam and is spongy and light like popcorn. Like sphagnum peat moss, it also absorbs much more than its own weight in water, which helps keep your plants hydrated.

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Other alternatives

A few additional soil conditioners that do an excellent job of replacing sphagnum peat moss are cellulose mixes from recycled paper or rice hulls and peanut shells from food processing.

How to Use Sphagnum Peat Moss

Sphagnum peat moss may simply be the necessary way to go for one reason or another. For example, you may decide to use it sparingly just for a few of your most acid-loving plants. It also makes an excellent seed starter medium, which means your consumption would prove meager.

For potted plants

When potting plants with garden soil, you’ll probably need to amend it with sphagnum peat moss and other materials to make it suitable for containers. While garden plants in the ground can reach out with deep and wide-spreading roots to find water and nutrients, container plants live at the whim and mercy of the contents of their pots.

To mix with garden soil, mix it 2-to-1 with peat moss. You may want to even cut the sphagnum peat moss with other materials like vermiculite.

Unless you have room and time for mixing your own potting mix, you may choose to simply buy a pre-mixed potting soil. Many commercial producers have already amended their mixes with sphagnum peat moss, vermiculite, or perlite. Many producers even add a slow-release fertilizer.

For seed starting

Experiment with producing your own starter mix, depending on what seeds you’ll be starting. While most seedlings need a light and fluffy medium to grow roots quickly, some require a more substantial mix. For those, mix three equal parts of garden soil, sphagnum peat moss, and vermiculite or perlite.

For a very light, soilless seed starter mix, mix one-part sphagnum peat moss and one part vermiculite. You’ll also need to add some nutrients to this mix, and a very dilute formula of a balanced organic fertilizer should provide those required.

To Peat or Not to Peat

Whether or not you decide to use sphagnum peat moss in your garden depends on the soil requirements of your plants and your feelings about sustainability. Cost may even be a factor for you.

While environmentalists are concerned, you’ll be able to find sphagnum peat moss on the market in the U.S. for many years to come. You can certainly use it responsibly, reserving it only for plants that need acidic soil and for starting seeds.

For larger gardens and more accommodating plants, however, it pays to consider the alternatives. Leaf mold, dried lawn clippings, and compost are all readily available and best of all, completely free. You can sometimes get wood chips from your local county waste department for free or a small sum. On Chip Drop, you can request local arborists to deliver their clippings for free.

Sphagnum peat moss has been an important part of advancing horticulture, freeing both home and commercial gardeners from being captives to the quality of their garden soil. Use it well and wisely, and you’ll find your vertical garden thrives under the benefits.

Last update on 2022-01-27 at 20:02 / Affiliate links / Images from Amazon Product Advertising API


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