When I first planted fruit trees, I knew I needed to mulch them. After all, when you visit any well-tended garden, you will see a pretty circle of mulch – usually wood chips or cedar mulch – carefully spread out around the base of the trees. But what exactly is tree mulch?
Mulch is a name used for any material that we use to cover bare soil. People mulch their trees with organic materials like wood chips or compost, or with inorganic materials like gravel, plastic sheets or landscape fabric. There are two main benefits:
So, let’s explore some great tree mulch options and when you might use them on your fruit trees. You can also try some of them on your native and ornamental trees as well.
Wood mulch can come in various colours including natural, red and black. Red and black wood mulches are dyed with chemicals and should be avoided to prevent the dye from moving into the soil. Photo Credit: OrchardPeople.com.wood mulch – and why it’s not always good for fruit treesCedar mulch is one of the most popular wood mulches that you can buy and many people use it on landscape trees. But there are other wood mulch options including hardwood mulch, pine mulch and bark mulch. Wood mulches have lots of benefits. But used on their own, many wood mulches can actually be bad for fruit trees – especially young trees.
The problem begins when you first lay the fresh mulch down around the roots of your fruit tree. Soil bacteria move into the mulched area and they will work to decompose the wood. But these bacteria need nitrogen in order to survive and wood chips are low in nitrogen. So, the bacteria pull nitrogen out of the soil and away from the roots of your fruit tree.
For fruit trees, this is not a good thing. Nitrogen is an essential nutrient for fruit trees and it gives them the nutrients they need for healthy leaf and branch growth. Trees that are low in nitrogen will not grow well and will experience stress. Young fruit trees that have not yet established themselves are particularly vulnerable to this problem.
But there are also benefits to using wood mulches around fruit trees – especially if you are layering the wood mulch on top of a more nutrient rich mulch like compost or well-rotted manure. We will talk about nutrient rich mulches in the next section. In the meantime, here are the advantages and disadvantages of a number of wood mulches that are available.
Compost or well rotted manure can be a nutritious tree mulch. Photo Credit: OrchardPeople.com.nutrient rich fruit tree mulchesIf you really want to use a wood mulch around your fruit trees, you’ll want to layer it on top of another mulch that will offer nutrients to your tree in the first year. In Ben Nobleman Park Community Orchard, we use either compost or well-rotted manure for that.
Compost contains small amounts of all three primary nutrients that trees need: nitrogen, phosphorus and potassium. If you mulch your trees with one to two inches of compost in the spring, that compost will insulate the roots and prevent weeds like wood mulch but it will also add nutrition and organic matter to the soil over the following weeks and months. You can learn about the role of compost in building good soil in this podcast.
Manure can also be helpful. Manure usually contains nitrogen but not much phosphorus or potassium. But the problem is that fresh manure can actually burn tree roots and it can have pathogens in it that are toxic to humans. The manure that you buy from your local garden center will be composted and so it is safe to use. You might also consider buying dehydrated chicken pellets instead of using composted manure.
Like compost, leaf mold has small amounts of nitrogen, phosphorus and potassium. But while compost is produced by soil bacteria, leaf mold is produced by beneficial fungi in the soil. This is an amazing product to mulch with because it’s free and easy to make. Leaf mold also feeds beneficial microorganisms in the soil while improving soil texture and your soil’s ability to hold water.
To make leaf mold, just collect fallen leaves from your neighborhood. Avoid diseased leaves that can introduce a pathogen into your soil. And you might also want to avoid oak leaves which break down very slowly. Pile the leaves up in a corner of your garden, spray them lightly with water, cover the pile with a tarp and then wait for the beneficial fungi to do their work!
In one to two years, the fungi will have broken down the leaves, leaving behind a dark brown crumbly leaf mulch with a nice, earthy smell. Don’t want to wait that long? Just shred your leaves with a lawnmower or leaf shredder before adding them to the pile. This will make it easier for soil fungi to do their work and your leaf mold could be ready in a year or less.
Straw can be used as a mulch for fruit trees. But it's important to be sure that the straw doesn't contain seeds to prevent bringing unwanted plants and weeds into your orchard. Photo Credit: OrchardPeople.com.affordable mulches for larger orchardsAll of the mulches we have discussed so far are great for any type of tree, including fruit trees. But there are a number of mulches that researchers have experimented with that are particularly good to use in orchards.
You see, if you are just planting one or two trees, it’s not that expensive to buy and bring in some bags of compost or mulch. But if you need to mulch an entire orchard of ten thousand fruit trees, that will be incredibly expensive.
In an episode of The Urban Forestry Radio Show and Podcast, I spoke to Professor David Granatstein of Washington State University's Center for Sustaining Agriculture and Natural Resources about the mulches that researchers are testing for use in orchards. Here are some of his top picks.
Straw mulch is often used when you are growing strawberries. It keeps the berries from touching the soil, retains moisture and protects the roots of the plants from extreme hot or cold temperatures. Straw mulch is also beneficial for fruit trees. While it is not as nutrient rich as compost, it will eventually break down and provide some nutrition to your fruit trees. The tricky part is ensuring that your straw is seedless! Ideally it should be harvested before the plant (often alfalfa) produces seeds. If it’s harvested too late, you may find that your mulch produces more weeds than it prevents. Straw mulch can also attract voles and other rodents who use the straw as habitat. These creatures then chew up the bark on our fruit trees. So, if voles are a problem in your community, avoid straw mulch.
Shredded Paper is a surprising option that, according to researchers, can be a cheap and effective fruit tree mulch. The shredded paper knits together over time to form a layer that prevents weeds. Shredded paper mulch is great because it is lightweight and you can easily make it at home with paper that you would send to be recycled anyways. Just feed your scrap paper into an inexpensive paper shredder and lay it down around your fruit tree’s roots. When it decomposes, the paper will add organic matter to your soil. The downside is that shredded paper mulch is low in nutrition but if you layer it with compost you could have a really easy and inexpensive way to protect your fruit tree from weeds and to feed it at the same time.
Living mulches are becoming increasingly popular. These are also called cover crops or green manures and they are incredibly flexible. Some help us fight weeds. Some stabilize the soil or provide increased nutrition. Organic orchardists will plant these living mulches in alleys between trees. But the secret here is to choose the right living mulch for your unique needs. You can learn more about cover crops in this radio show and podcast.
The downside of living mulches is that like straw mulch, they can attract pests like rabbits and voles. Some living mulches can also be invasive in certain conditions. So, you need to do a little research before using these types of mulches.
Pruning is an essential part of fruit tree care. But what do you do with the young branches that you remove from the tree? They can make a fantastic, nutrient rich fruit tree mulch. Photo Credit: OrchardPeople.com.is ramial mulch the perfect mulch for fruit trees?So far, we’ve covered lots of different mulching options. But there is one option that was overlooked for most of humanity’s fruit tree growing history.
You see, pruning plays a huge role in how we care for our fruit trees. We prune fruit trees annually in the spring or summer to improve tree health and harvest quality. And when we are done, growers often burn the cuttings or throw them away.
What few realized until recently is that the youngest tree branches – those that are under 2 inches thick, can be the perfect mulch for fruit trees. These tender young branches are rich in nutrients that fruit trees need like nitrogen, phosphorus, potassium, calcium, and magnesium which can be found in the cambium, or the living tissue in the branch. And if you cut these young branches up or shred them, they will eventually decompose, releasing nutrients into the soil where they will eventually be available to our fruit trees.
Mulch from young tree cuttings is very different from wood mulch, as the latter is made from thicker, older branches and the tree trunk. These older parts of the tree do have cambium tissue, but they are mostly made up of heartwood which has a lower nutritional value.
In terms of mulches from tender young branches, there are two amazing options to consider.
Or you can buy an electric chipper and shredder. Just feed the young branches in and you’ll have ready-made ramial or willow mulch that your fruit trees will love.
One warning though…. only use healthy branches when making these types of mulches. If the branches are diseased, then that disease will be able to continue to spread if it’s left on the site.
Do ramial and willow mulches come with a down side? Well, like wood mulch from mature branches, they may also steal nitrogen from the soil in the first year. So again, it’s good to layer your ramial or willow mulch on top of compost or manure to ensure that your fruit tree will be able to access nutrients in the shorter term as well.
Finally, let’s explore non-organic tree mulch options and why you may not want to use them with your fruit trees.
Gravel or river rocks can be used as a non-organic tree mulch. It will help prevent weeds around the base of the tree but has little nutritional value. Photo Credit: OrchardPeople.com.why non-organic mulch options can miss the mark with fruit treesLandscapers often turn to non-organic mulch options in order to keep landscapes looking perfect. Some mulch trees with gravel. Others use landscape fabric and they cover it up with wood mulch. Some even use black plastic to mulch around their trees. When it comes to fruit trees these aren’t great options. Here’s why:
Landscape fabric covered with wood mulch will prevent weeds around the base of the tree. But fruit trees need organic matter and nutrients. If there is a fabric barrier between the wood mulch and the soil, how will you feed your tree? The nutrients from the decomposed wood mulch won’t get through. And in order to feed your trees with compost, you will have to remove the fabric and then put it back. This is not a great option.
Black plastic mulch sheets are even worse. Your fruit trees need nutrients which won’t get to the root through the plastic. But the roots also need water and oxygen. Black plastic will limit the moisture and air that can get through into the soil. This is another option to avoid when growing fruit trees.
Some orchards do use gravel to mulch their fruit trees. Their goal is to prevent weeds and deter rabbits and other wildlife that might nibble on the bark of their trees. But again, with gravel, you are missing your opportunity to feed your fruit tree with your mulch. If you do use it, you’ll have to pull the gravel back each year, add a nutritious mulch like compost, and then replace the gravel.
If you are going to use wood mulch, it should be layered on top of a nutritious mulch like compost or rotted manure. That's because decomposing wood mulch can draw nitrogen out of the soil and that can cause tree stress and nutrient deficiencies.layering mulches to maximize benefitsWhen it comes to fruit trees and mulch, there is no one size fits all option. You will choose your mulch depending on your unique environment and the goals that you want to achieve. But sometimes, two mulches can be better than one. Here are some examples:
The first step to mulching your tree is to remove the grass and weeds up until the edge of the tree's canopy because that is where your tree's feeder roots are. Feeder roots take in nutrition and water. Photo Credit: OrchardPeople.com.how to mulch your fruit treeNow you have lots of options in terms of fruit tree mulches. But once you have chosen what to use, how do you mulch your fruit tree? Here are a few simple rules:
Happy mulching everyone!