Wood chips are a popular garden mulch made from ground up pieces of tree bark and wood. But are they actually good for your garden? As it turns out, using wood chips in the garden has a number of benefits, but there are also some potential downsides to be aware of. In this detailed article, we’ll examine the pros and cons of using wood chips in the garden so you can decide if they are right for your plants
Benefits of Using Wood Chips in the Garden
Here are some of the main benefits of using wood chips as mulch in the garden:
Weed Suppression
One of the primary benefits of mulch, including wood chip mulch, is suppressing weed growth. The chips block sunlight from reaching weed seeds and seedlings, preventing them from germinating and growing. The physical barrier created by the mulch also makes it difficult for weeds to push through. This weed suppression can significantly reduce the need for weeding and maintenance in garden beds.
Moisture Retention
A thick layer of wood chip mulch helps retain moisture in the soil underneath. The mulch prevents evaporation, keeping the soil consistently moist. This can reduce the frequency of watering needed for garden plants. As the chips break down, they also improve soil structure allowing it to retain even more moisture.
Temperature Modulation
Bare soil can heat up and cool down quickly, resulting in temperature extremes Wood chip mulch creates an insulating barrier between the soil and sun/air, moderating soil temperatures This helps protect plants from extreme heat and cold.
Erosion Prevention
When soil is left bare, heavy rain can easily wash it away. Wood chip mulch forms a protective layer over the soil that shields it from the direct impact of rain and water. This prevents erosion, keeping valuable topsoil in place.
Improved Soil Nutrients
As organic wood chips break down, they release nutrients like nitrogen, phosphorus, and potassium into the surrounding soil. This improves overall soil fertility and health. The added nutrients benefit plants as well as soil organisms.
Enhanced Biodiversity
The nutrients released from decomposing wood chips help support a variety of beneficial soil organisms like bacteria, fungi, insects, and worms. These organisms further enhance soil health. An overall boost in soil biodiversity creates a thriving environment for plants.
Potential Downsides of Wood Chip Mulch
While wood chips offer many benefits, there are also some potential downsides to consider:
Can Harbor Pests
If not from a reliable source, wood chips could contain insects, larvae, or eggs that can lead to pest problems in the garden. Termites are a particular concern with wood mulches. Always inspect chips for signs of pests before spreading.
May Spread Disease
Using wood chips from diseased trees can spread issues like blights, molds, and fungal infections to garden plants. It’s safest to only use chips from trees you know are healthy.
Can Tie Up Nitrogen
As wood chips decompose, the process can temporarily bind nitrogen in the soil, making it unavailable to plants. This is usually only an issue if tilled into the soil. Applying to the surface minimizes nitrogen loss.
May Encourage Fungi
The moist environment under wood mulch can sometimes promote excessive fungal growth. Good airflow is key to preventing this. Allow the mulch to dry out between waterings.
Can Look Messy
Wood chips tend to look less tidy compared to finely shredded hardwood or dyed mulches. Their coarse texture and natural colors may detract from ornamental appeal for some gardeners.
Needs Replenishing
Unlike inorganic options like pebbles or rubber mulch, wood chips decompose fairly quickly and need reapplying every 1-2 years. This maintenance can be seen as a downside.
Good Types of Wood Chips for the Garden
If you do opt to use wood chips in your garden, make sure to choose an organic, chemical-free variety. Some good options include:
- Pine bark chips
- Cedar chips
- Hardwood blend chips
- Shredded cypress or pine straw
- Aged chips that are darker in color
Avoid using wood chips from walnut or eucalyptus trees, as these can inhibit plant growth. A 2-3 inch layer of chips is ideal for most gardens. Ultimately, wood chip mulch can be very beneficial in the garden if used properly. Just be aware of potential drawbacks and make sure it’s a good match for your specific conditions and needs.
What are recommendations for using arborist chips in a vegetable garden?
Please provide recommendations for using arborist chips in a vegetable garden for plants and seeds.
Abi Griffith, Horticulture Community Education Assistant
Wood chips are really great for mulching in perennial beds, around raspberries or high bush blueberries, on permanent walkways or between raised beds to help with weed suppression and water retention. They can also be used in your compost pile (see page 2), if you have one, as a carbon source, for a healthy pile. Generally, when it comes to wood chips and vegetable and herb gardens, you want to avoid directly mulching or mixing chips into the soil or garden bed you are planting into. But, again, it could be effective, applied thickly in between your beds. Bark, and wood chips, because of their high carbon content, can cause “nitrogen lock-up”, where soil organisms actively consume the carbon in the wood chips, using available nitrogen in the process, and potentially depriving your vegetable plants of much needed nitrogen. It would be better to stick to mulches like straw in your vegetable garden beds. . I included a few pictures of how we use wood chips between our vegetable beds at our demonstration gardens at Tidewater Farm for a visual. The second picture you can see straw mulch used in the actual beds.
You may want to check out these fact sheets from the Colorado State Master Gardener Program that go into more detail about appropriate use of mulches, including wood chips. Additionally, if you have more than you can use in a few years, I’m sure your gardening friends and neighbors would love to hear from you!
Best Wood Chip Mulch for Your Vegetable Garden
FAQ
What are the disadvantages of wood chips?
The mulch also hides the soil, making it more difficult to know when to water. Also, wood chips break down and must be re-applied every year or two. Wood chips can also harbor insects that may attack plants, including slugs, earwigs, sowbugs, and ants.
What plants don’t like wood chips?
There are some species that tolerate excessive mulch better than others. Some of the worst effected plants are grassy plants (iris, daylilies, liriope, etc.), Indian Hawthorn, Azaleas and Loropetalum.
Are wood chips good for vegetable gardens?
Yes, wood chips can be beneficial for vegetable gardens, especially when used as mulch. They help suppress weeds, retain soil moisture, regulate soil temperature, and add organic matter as they decompose.
Can I mix wood chips with soil?
it’s fine to put woodchips on top of soil as mulch, just don’t mix them in with the soil.