Mulch: It's definitely spreading
Mulch used to be the finishing touch on highly sculpted landscape projects, now everybody mulches. Gardeners now spend half a billion dollars a year on mulch. The word "mulch" does not mean just wood chips or shredded bark. "Mulch" is anything that covers the soil to retain moisture and prevent weeds. There is no better mulch than compost. And, if you use wood chips or shredded bark in a plant bed as mulch, please spread compost first!
Most smart gardeners mulch twice a year -- once in spring to protect plants from the heat and again in the fall to protect them from the cold. That is what I recommend to my clients. If they’re going the extra mile they’ll do a layer of mulch topped with bark mulch. This balances out the carbon and nitrogen added to the soil.
Other gardeners hope to mulch once and never again. They are the ones who blanket their flower beds with stone, crushed brick, oyster shells, marble chips, lava rock and – hopefully not in Sonoma County -- black plastic or shredded rubber. There are even "novelty" mulches. They come in a variety of colors and scents. You can purchase a mulch made of cocoa bean shells that smells of chocolate – however, it is dangerous for pets to ingest.
Mulches are available in two major forms, organic and inorganic. I prefer organic mulches, such as wood chips, pine needles, hardwood and softwood bark, cocoa hulls, leaves, and compost mixes, since they decompose, improving soil structure and increasing soil fertility.
Photo by Tobias Bjørkli
Who invented mulch?
The true pioneers of using seaweed as mulch are Scottish and Irish farmers. Noting the high degree of nutrients and its abundant nature, it was a natural fit for these farmers for hundreds of years and even today.
Does mulch improve soil?
Smart gardeners improve their soil and weed control with organic mulch. A blanket of mulch helps regulate soil temperatures and slow moisture losses to create the perfect environment for plant roots. Additionally, organic mulches break down over time. Increased organic matter aids the soil's ability to retain plant nutrients such as potassium, magnesium, calcium, and iron.
When should I mulch?
Avoid putting down mulch too early. Normally, mid- to late spring is the best time to put down mulch. Seedlings can work their way through a thin layer of mulch, but too deep a layer could be impenetrable. Let your plants get off to a good start first. You can always add more mulch after the plants are established.
What are the main purposes of mulches?
The main purposes of mulch are to suppress weeds, enrich the soil with nutrients, regulate soil temperature, improve moisture retention, prevent soil erosion. In essence, mulch suppresses the growth of unwanted weeds while enriching the soil allowing plants to thrive
One of the purposes of mulch is to retain moisture, so you'll want to wait to apply new mulch. If you still have a thick layer of mulch from last year, you should use a cultivating tool to loosen it. This will allow more air into the soil to help it dry out. Mulch should be replenished or replaced as you start to see signs of decomposition, soil erosion and discoloration.
Photo by Greta Hoffman
Which wood mulch is best?
Many local gardeners prefer organic brown as the most natural-looking mulch but will make exceptions and use black dyed mulch in a very targeted way in a specific area of the yard.
Regular mulch turns a shade of gray as it fades in the sun. In fact, in as little as one to two months, regular, non-dyed brown mulch can become gray. Meanwhile, dyed brown mulches or black mulches can last for a minimum of a year, and in some products longer with little color loss.
What are the disadvantages of mulching?
The main disadvantage of mulching is that it can create a hiding place for harmful insects, and when applied too thickly can suffocate your plants by overheating the soil and starving them of light and water.
Bulk much or bagged mulch?
Bulk mulch has numerous benefits. It is often less expensive than the same amount of mulch purchased in bags. For example, one cubic yard of mulch will equal about 13.5 bags of mulch. It is usually fresher; bagged mulch is often sold 3-6 months after being ground and bagged. However, you do need to put it in the back of a truck or have it delivered. Then again, your time behind the wheelbarrow to spread the mulch counts too!
Bagged mulch has a number of benefits too! The convenience of the bags is at the top of the list. If you don’t have access to a pickup truck or don’t envision a pile of mulch in the driveway, this is the choice for you. You can also drag it around your yard without a wheelbarrow. And it can be stored for later.
Does mulch turn into topsoil?
Rather than think of mulch as slowly becoming soil, think of mulch as gradually transforming into compost as it decomposes. Compost (and decomposed mulch) are rich with nutrients and healthy microorganisms that help battle weeds, feed plants, and balance the pH levels in your soil. Mulch feeds soil biology as it decomposes, helping to create healthy, living soil. Healthy soil means healthy plants!
What wood mulch breaks down the fastest?
Shredded Bark: Like shredded hardwood, this mulch is easy to spread in landscapes and provides beneficial moisture retention. Shredded bark mulch breaks down much faster than mulch nuggets — conditioning the soil in the process. Locally, we call it arbor mulch.
Can I spread mulch around trees?
Photo by Alfo Medeiros
This is actually a much debated topic in landscaping. Some believe that you shouldn’t mulch around a tree as the roots will rise up into the top layer of the soil and it can cause issues. Others point out that trees are naturally mulched by leaves in the wild.
Never touch a tree with any mulch. Mulches are for preventing weeds and retaining soil moisture --- they are not meant as socks for tree trunks! Always leave a few inches wide open around the trunk of a tree.
Mulch reduces weeds, conserves moisture and improves the soil, which helps your tree stay healthy! But when it comes to mulch, it is possible to have too much of a good thing. Piling mulch too high and covering a tree's trunk, also known as “volcano mulching,” can cause decay.
So, keep mulch away from a tree’s trunk!!
Just remember to keep ALL mulches six inches away from the trunk or stalk of any plant; any mulch will rot a plant it's piled against. Keep all mulches six inches away from your home as well; termites will use ANY moisture-conserving cover—even stones—to reach your framing.
Do you mulch, if so what’s your favorite material to use?