There are many different options when it comes to mulch, including plastic mulch, rocks or gravel, rubber mulch, straw, wood bark, and wood chips. The general consensus is that any mulch is better than no mulch for plant growth and success. 

However, we continually hear from our customers and other experts in the field that wood chip mulch is the ideal mulch to add to your landscape. It can benefit your garden, plants, and soil in a variety of ways. But we think that the biggest benefit is that it makes your job of caring for your trees, shrubs, and gardens easier.

Weed Control

When planting young seedlings, it is important to remove surrounding vegetation that will compete for resources. One way of controlling the weeds in the area is through the use of mulch. Adding a layer of wood chips acts as a separation from the underlying soil. If the mulch is thick enough (at least 10 cm) it can prevent weeds from germinating. As wood chip mulch decomposes over time it will become less successful at controlling weeds, so reapplication of mulch may be necessary down the road. While mulch isn’t the perfect cure for weeds, it will reduce the number of weeds and make dealing with them a lot easier. 

Soil Benefits

Here are four benefits to your soil wood mulch can help with Moisture, Quality, Temperature, Erosion & Compaction. Keep reading for more details.

1. Soil Moisture:

Mulch increases soil moisture by increasing water permeation and retention while reducing evaporation. The coarse texture of the wood chip mulch makes it more effective at moisture retention than mulch with a finer texture. Instead of having excess water lost as runoff. The coarse wood chips will absorb the water, much like a sponge, and later release the moisture to the soil below. Rather than losing this precious moisture to the surrounding area or the atmosphere, it goes where it is needed most: to the plants. 

This can be critical for a plant’s success, especially during dry years and droughts. It can also decrease the amount of times you have to water or irrigate. Maintaining soil moisture is particularly beneficial for young seedlings still developing their roots and trees with shallow root systems. Trees with deeper, established roots can access water that is found deeper within the soil.

The benefit experienced will vary from project to project. Moisture retention will be more significant for trees and shrubs that have their surrounding soil fully exposed to the sun and wind. Soil that is already shaded by tree canopy and understory plants will not experience as noticeable of a benefit.

2. Soil Quality:

Wood chip mulch varies in size which causes their decomposition rate to vary. As they gradually decompose, they add beneficial nutrients and minerals to the soil. This includes nitrogen, phosphorus, and potassium. Research even shows that as the thickness of the mulch increases, so does the nutrient content of the soil. This increase in nutrients is important for establishing new trees or for those planted in poor soil.

One myth regarding mulch and nutrients is that organic mulch can deplete with nitrogen from the soil. However, any decreases in soil nitrogen only occur in the thin top layer of soil. This does not negatively impact the plants as their roots are found beneath this level. Lower nitrogen levels at the surface of the soil have the added benefit of making it hard for weeds to germinate.

3. Soil Temperature:

Wood chip mulch can help protect the underlying soil from extreme temperatures, keeping the planting site more consistent. During hot conditions, mulch will keep the soil cooler by as much as 10°C when compared to bare soil. Bare soil will absorb a large amount of heat from the sun, whereas wood chip mulch absorbs very little and dissipates that heat. The opposite is true during cold months. The mulch layer will act as insulation for the roots below and keep the soil temperature warmer. Coarser organic mulch and thicker applications are more successful at temperature moderating.

Extreme temperatures can cause fine roots to be damaged or killed off, especially at the soil surface level. While this won’t necessarily kill an established tree or shrub, it can cause them stress. Whereas, a young seedling or recent transplant that is in the process of establishing roots, the loss or damage of the surface-level roots could be fatal. 

4. Soil Erosion & Compaction:

Bare soil is more susceptible to both erosion and compaction. Adding even a thin layer of wood chip mulch will help protect the soils from compaction and erosion. While mulch will not be able to stabilize the soil in ways that plants and soil engineering solutions will, it still helps to prevent surface erosion. 

It is easy to understand that areas with foot, animal, or equipment traffic will experience soil compaction. However, when the soil is bare even rainfall can compact the soil over time. Adding a layer of mulch will help protect the soil by dispersing the impact of the compaction forces. Adding mulch will only be able to prevent further compaction from occurring and will not reverse compaction after the fact. So the best time to add mulch is now. 

Compaction is one of the key factors that can prevent or limit tree growth. It can make or break a planting project. As soil becomes compressed and compacted it absorbs less water, making less available for the plants. Root growth will be limited as their ability to penetrate the soil will be reduced. This can cause shallow or even malformed roots, making overall plant growth difficult.

Conclusion

Adding wood chip mulch to your landscape can address multiple concerns that can impact plant survival. Mulch will promote root establishment, improve seedling and transplant survival, and can increase overall plant growth. This is due to all the factors that mulching will impact. Plants respond positively to less competition with weeds, improved soil quality, less compaction and erosion, and consistent planting site characteristics. At the end of the day, this means healthier trees and shrubs that require less maintenance, which makes your job a lot easier. 

Any mulch is better than no mulch!

So whether you are concerned about dry conditions and drought, competition with weeds, or soil quality, adding mulch to your landscape can be the solution. Depending on the size and scale of your project, there are many different options of mulch to consider. There is a wide range of information out there on the various mulch options. By doing your research you can come up with a mulching solution that works for you. We always love learning from our customers’ experiences.

If you have project success stories or information to share please let us know by emailing at [email protected] or by phone at 1-844-873-3700. Visit TreeTime.ca for all your tree and shrub needs for your project.

References

  1. Linda Chalker-Scott, “Impact of mulches on landscape plants and the environment – A review,” Journal of Environmental Horticulture, December 2007.
  2. “Mulch & more: A how-to-guide to a healthy yard,” Gardening at USask, December 27, 2022.
  3. “Mulch and soil nitrogen,” Gardening at USask, April 26, 2022.
  4. Linda Chalker-Scott, “Wood chip mulch: Landscape boon or bane?,” Master Gardener, Summer 2007.
  5. Jim Downer, “Mulch affects on trees,” Western Arborist, Summer 2009.
  6. Nicole Stoner, “Mulch in the landscape,” UNL Water, October 24, 2023.