A Beginner’s Guide to Peat Humus



Peat humus seems to be one of those “magical” soil amendments that can fix whatever ails your garden (assuming you can find any to purchase). But is this perception accurate? Let’s find out.

A Beginner's Guide to Peat Humus

A Beginner's Guide to Peat Humus
A peat bog being harvested

Many gardeners sooner or later wonder about peat humus, particularly what it is and what it is used for. Peat humus seems to be one of those “magical” soil amendments that can fix whatever ails your garden (assuming you can find any to purchase). But is this perception accurate? Let’s find out.

Commonly Confused Soil Amendments

Peat humus is frequently confused with peat moss. Little wonder, since not only are the names similar but the two products come from a similar source. Peat moss is partially decayed sphagnum moss, a species of moss that grows on top of bogs. Peat humus is a combination of sediments and more thoroughly decayed peat moss that collects at the bottoms of bogs. Peat humus is darker in color and finer in texture than peat moss.

Another source of confusion is peat humus and just plain humus. Humus is the part of the soil that is without structure and is made up of the entirely decomposed remains of plants and animals. Humus can be derived from many different sources, not just sphagnum moss. Peat humus is therefore a specific type of humus.

Peat Humus Benefits

Peat humus can dramatically improve the following aspects of soil:

  • Structure.
  • Drainage.
  • Moisture retention.
  • Nutrient retention.
  • Heat retention.

Some experts also believe that peat humus may be able to help plants process and eliminate heavy metals. It may provide a further boost in plant health by fostering microbial growth.

Peat Humus Drawbacks

Peat humus is one of the more expensive and hard-to-find soil amendments out there, which has precluded it from more common use.

While peat humus does have moisture-retaining properties, it is not as effective as peat moss. However, this is not necessarily a bad thing, as peat moss is so notoriously “thirsty” that it must be watered down before application to avoid completely drying out the soil.

Be aware that peat humus is low in nutrient content. Its purpose is to improve the structural qualities of soil. If you are wanting to boost soil nutrients, you will need to use a different ingredient, such as compost.

Is Peat Humus Sustainable?

Sustainability is a common concern with peat humus, because this soil amendment is harvested from peat bogs. Peat bogs appear to form and decompose slowly. Indeed, scientists believe that it can take hundreds of years for peat humus to form. This means that we could theoretically harvest peat humus faster than it is regenerated.

However long peat humus takes to form, it definitely takes much longer than peat moss because it must undergo more extensive decomposition. In practice, this makes peat humus rather scarce, which is why it is so expensive.

Best Uses for Peat Humus

Peat humus is well suited to the following applications:

  • Acid-loving plants. Plants such as blueberries will appreciate the low pH that peat humus can contribute. Just be aware that the adjustment tends to be short-lived due to leaching, so you may still need to adjust the pH from time to time.
  • Clay soils. Clay soils are notoriously heavy and slow to drain. This makes peat humus a natural choice for improving the situation, at least on a small scale.
  • Raised beds. Peat humus has an ideal texture and structure for growing many types of plants. Using it in combination with a nutrient-rich ingredient such as compost to fill raised beds is a good way to maximize the value you obtain for the price. Be aware that the pH may start out too low for some plants. A little watering should help.
  • Roses. Peat humus can be useful in growing extra-large roses if used cautiously and in moderation. Fork it into the soil to improve structure and moisture-retaining properties as needed. Large quantities will lower the pH too much (at least for a time) and will not provide the nutrients that are necessary for big, beautiful blooms.
  • Vegetable gardens. If you can afford it, peat humus can give a tremendous boost to the health and growth of your vegetables by improving the soil. It may be a little too acidic for some plants at first, but the effect should be short-lived if you water regularly. Also be sure to add organic fertilizers for a nutrient boost, which peat humus alone cannot provide.

On a more unusual note, some natural supplement manufacturers are straining peat humus through water to create humic acid supplements for human use. These supplements are thought to help in vitamin absorption and heavy metal elimination.

Cases where peat humus is not ideal include the following:

  • Compost. Adding peat humus to compost is frankly rather pointless, as the purpose of composting is to break organic matter down into humus, and peat humus is humus already. Peat moss, however, is an excellent addition to the compost pile, as it can improve moisture retention.
  • Lawns. Peat humus is a poor choice for topdressing lawns. For one thing, it is way too expensive to be spread over a lawn of any size. For another thing, grass will grow poorly if peat humus is the only amendment used due to its low nutrient content. A better option is a topdressing of cheaper peat moss in combination with topsoil and sand, perhaps with some weed-free compost.
  • Potting soil. Peat humus is not recommended for potting soil largely because it is so expensive and hard to find. The good news is that the more readily available peat moss is actually better for seed-starting and potted plants because it is lighter and retains moisture better. (Note, however, that you will still need to add a substance that contains nutrients, as you would with peat humus.)
  • Tomatoes. Tomatoes do not develop a full-bodied flavor on soils with high peat content. While tomatoes will indeed benefit from the addition of a enough peat humus (or peat moss) to improve the soil texture and drainage, make sure the soil for your tomatoes includes ample mineral content.
Improving Your Garden Soil