Composted bark is made from the offcuts from the timber industry or tree trimming from arborists. The bark pieces are often from pine trees but can be made from any tree that is collected. The tree offcuts are broken down into small shavings in an industrial sized drum grinder and composted.
These bark pieces are composted or broken down so they can be used as a growing medium or as a mulch. Composted bark is the main ingredient for potting soil mixes. Mixing together composted bark, coarse river sand and aged manure makes the perfect potting soil.
NOTE: Composted bark is different to bark mulch. Composted bark will be broken down and can be mixed into soil. Bark mulch will contain larger tree pieces, usually pine which will not be broken down and cannot be mixed through soil. Bark mulch should only be applied to the surface of soil.
Composted bark is available in bags or from your local landscape supplier. Make sure you ask for composted bark for potting soils rather than bark mulch.
Make sure that if you plan to dig composted bark into your soil that is has been fully broken down, is in fine pieces, resembles soil and is dug into the top soil.
Digging bark through your soil that is not fully broken down will draw nitrogen from the soil and can stunt plant growth.
How to use composted bark in your garden
If you have bought composted bark from your local garden center or online you can use it in many ways at home. It will look like potting soil so can be mixed together with other ingredients or your soil to improve it.
Here are the top ways to use composted bark at home. Remember, this is not bark mulch but a composted bark material similar to potting soil.
1. Improve clay soils
Heavy clay soils can be lightened with composted bark. Grab bags of composted bark and mix it through the top 4-5 inches of soil. This will help to mix through more organic matter, add air pockets and let water drain through easily.
2. Improve sandy soils
Composted bark can be used to increase the water holding capacity of sandy soils. Mix this material through your sandy soil to add organic matter and help to capture water from the rain. This will help to keep plant roots moist and help with healthy growth.
3. Use as a mulch
Composted bark can also be used on top of the soil as mulch. This product will help to stop water from evaporating from the soil surface, will keep plant roots moist, add organic matter to the soil and prevent weeds.
Layer 2-3 inches of bark mulch on top of the soil to stop weed seeds underneath from getting light. This will help to stop them sprouting and growing.
Benefits of composted bark
Here are the top benefits of composted bark for your soil and garden. Remember to check that the bark has been fully composted and resembles fine potting soil before digging it through your garden. You can add it to your compost bin to break down further if it has not fully broken down.
1. Improves soil structure
Mixing through organic matter like composted bark will help to improve soil structure. This means that clay soils will drain better and sandy soils will hold water. Adding organic matter helps to feed the worms and soil bacteria who will mix the compost through your soil over time.
2. Improves drainage
Composted bark will help to improve drainage and help to prevent fungal growth and root rot. Plants that are sensitive to too much water benefit from added bark mulch. Composted bark mulch is used in orchid potting mixes because it drains well.
3. Adds organic matter to soils
Adding composted bark to soils will add plenty of organic matter. Soil bacteria feed on this organic matter breaking it down further and releasing the nutrients into the soil. This makes them available for plants to help with good growth.
4. Adds nutrients to the soil
Adding composted bark mulch adds a range of nutrients to the soil including nitrogen that will be released slowly over time. Composed bark mulch is a mild, slow release fertilizer as soil bacteria digest and release the nutrients into the soil for your plants.
5. Recycles a waste material from the timber industry
Turning the leftover pine bark waste into compost is a great way to recycle a waste material. Rather than ending up in landfill pine bark pieces are composted and returned to the soil in homes and commercial landscaping projects.
This composted material is a great way to capture carbon and save waste ending up in landfill.
6. Used to make potting soil
One of the main uses for composted bark is as an ingredient for potting soil. Potting soil is made largely of composted bark with a few other additives like sand and fertilizer. It is harder to find bags of pure composted bark but cheap potting soil is almost the same. It contains very little other additives and usually doesn’t contain fertilizer.
What is Composted Bark? | Summary
Composted bark is the result of composting bark pieces, usually pine bark. Composted bark will look like potting soil with fine pieces of organic material. You can buy it in bulk amounts from landscape suppliers as it is the main ingredient for potting soil mixes.
Make sure you ask for composted bark because larger bark mulch will not work the same and should not be mixed into soil.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.