As I’m moving wood chips provided by a local arborist to put around our fruit trees at Raintree Nursery on a recent winter’s day (fortunately without too much rain), I think to myself about the importance of mulching fruit trees. There are many benefits and reasons to mulch trees, as well as different ways to do it.
Coppicing is the periodic (on multi-year timescales, depending on the species) cutting back of suitable species back to their base. Many woody plant species (shrubs and trees) will resprout from the stump (termed epicormic regeneration, with dormant buds sprouting from underneath the bark), or from roots (suckering) after being cut down. This is an ancient method of sustainably managing forests in Europe that provided many economic and wildlife and ecosystem benefits. Coppiced hardwoods, including alder, beech, hazelnut, sycamore, and willow, can perpetually provide firewood and crafting and building materials without having to be replanted. Hardwoods that don't "bleed" too much from pruning are ideally suited for coppicing (or pollarding for that matter). Maples, for instance, tend to bleed a lot when cut. Most conifers do not resprout after being cut back to the stump. A notable exception is the coast redwood (Sequioa sempervirens). In fact, I should restate that: Most conifers do not resprout from the stump though many conifers do, in fact, exhibit this to some degree. People have been coppicing on multi-year timeframes for such a long time in some European woodlands that they have created a disturbance pattern of shaded and open areas that benefit many rare plants and animals.
For various economic reasons (including cheap fossil fuel energy that is changing the climate), coppicing largely died out in Europe in the 20th Century but has seen a renewal in recent decades out of conservation concern. Coppicing never developed as a disturbance regime on the frontier landscape of North America, where I imagine less human population density and supply exceeding demand have historically allowed more squandering of wood products. In the West and Southeast in particular, vast coniferous forests are sustained through clear-cutting and replanting. The home orchardist reading this may have the opportunity to manage a small woodlot through coppicing. In the realm of fruit and nut orchards, scionwood production for grafting may be stimulated through the cutting down of an unhealthy tree that is deemed unsalvageable through more balanced pruning. If not on rootstock, then many fruit and nut trees may be cut back to the stump and allowed to resprout.
This actually could be an appropriate option for “resetting” the wild growth of plums and figs, for a couple of examples. Hazelnuts actually benefit from being coppiced every ten years or so, though of course, that means waiting a few years after cutting for any nut production. Hazelnut wood can be used for crafting many things that the homesteading inclined mind may find useful and economical (especially within an environmentally sound framework transcendent of the climate-changing realities of consumptive modern life). Some items that can be made from hazelwood are hurdles, beanpoles, staffs, and walking sticks, charcoal, wattle, and daub, tool handles, fence posts, stack chairs, and more. In addition to hazelnuts, Raintree offers many other plants that could be appropriate for coppicing, including figs, mulberries, some of the fruit tree rootstocks, goji berries, goumi berries, aronia, and serviceberries.
As with all pruning, one of the keys to understanding coppicing and pollarding is apical dominance. To a greater or lesser extent in plants (and definitely greater with shrubs and especially trees) the top bud (apical meristem) exerts hormonal dominance over lateral buds (which, in a tree, can form branches). Removing the uppermost bud on the leader (top of a tree) by “heading back” releases lateral buds from this dominance. Pollarding involves making an initial heading cut on the leader to enforce a reduced height and then keeping lateral branches to a reduced length from the top and cutting them off six feet or so up the trunk. Pollarding can be used to bring an overgrown tree back to desirable height (e.g. within ladder’s reach). It can also be handy for maintaining trees in tight situations. Pollarding over many years will result in a tree with fat knuckles and a distinctive look that needs to be pruned regularly to stay that way. This is not recommended for maintaining a balanced fruit tree. Some pollarding in the first few years, followed by new pruning strategies down the road (such as selecting for a new central leader) could help regain control of an overgrown fruit tree. I must say that in general, thinning cuts, which remove branches cleanly at the branch collar, are recommended over heading cuts when pruning fruit trees. Even with pollarding, thinning cuts are better than heading cuts, if possible. This is because heading cuts don’t heal as well as thinning cuts and can be entry points for disease-causing organisms.
Mulching also reduces competition from grass and other weeds like dandelions, plantain, clover, or whatever other ground covers and herbs grow in the orchard. A fruit tree’s feeder roots extend to just outside of the drip line of the tree (the edge of its outermost branches), so having putting mulch under the tree up to the drip line will help reduce competition for resources (including water) from other plants. Trees with low branches may be difficult to get under for mowing or other mechanical grass control options. Herbicide may not be desirable. So, mulch is the answer for suppressing grass around the tree.
Mulch can come in many forms besides wood chips, including cardboard, plastic fabric, lawn clippings, leaf litter, and straw. All of these besides the plastic are highly desirable because they decompose over time, enriching the soil ecosystem. Mixing well-rotted compost or manure into mulch can speed up this process, though care should be taken to not over-fertilize and “force” fruit trees, especially young trees. Ramial wood chips are wood chips made from small-diameter branches and ideally chipped twice, meaning that there is more sapwood (primary xylem), phloem, and bark (meaning more live or recently alive tissue) relative to true wood (secondary xylem, meaning dead tissue, heartwood) than wood chips from whole trees. Wood chips from branches decompose faster because of this and provide nutrients sooner. It’s important to understand that part of how decomposition works is that bacteria basically use nitrogen to digest carbon-heavy matter like plant cellulose. Wood chips from branches give bacteria and other decomposers more to work with! So, the home orchardist can make their own ramial wood chips from pruning their own trees, though of course, the branches must not be diseased.
Our wood chips are locally sourced and free. In many areas, private arbor companies, municipal forestry or road departments, or utility companies that cut down and chip trees may provide free wood chips for pickup or even delivery. The backyard orchardists might not be able to take all the wood chips an arborist would want to drop in a driveway if the deliveries are ongoing, but it’s worth looking into because many arborists would just love a free place to dump chips. Check out this free service to get connected to arborists’ wood chips: https://getchipdrop.com/.
Wood chips I’ve used at Raintree have come from western red cedar, red alder, big leaf maple, western hemlock, and Douglas-fir trees. Different tree species make for different contributions and considerations as mulch for fruit trees. The cedar smells nice, but I only dare put it around old and well-established trees. This is because these “cedar” trees, which are technically not “true” Cedrus cedars (family Pinaceae) and are actually members of the cypress or redwood family Cupressaceae, produce chemicals that can inhibit the growth of other trees. Conifers as sources of wood chips in general might acidify the soil overtime, so that is something to be aware of when using them for fruit trees. I definitely don’t advise too much conifer mulch (especially not western red cedar or other cypress) around young fruit trees. Beware of other species that may be more or less toxic, such as walnuts (Juglans species) and (Robinia species). Faster-decomposing deciduous trees like alder, maple, willow, and birch can provide better mulch. Alder is especially great in our case. Willow wood chips have been shown to boost fruit trees’ immune systems (learned on the Orchard People podcast, see sources below)! Because bacteria use nitrogen to decompose wood chips, don’t overuse wood chips around young trees that have small root systems looking for nitrogen. Just enough to suppress grass around the tree is advisable.
In the long run, mulch, especially wood chips, help promote healthy woodland soil for fruit trees by breaking down and feeding the whole soil community from bacteria and fungi on up through nematodes, springtails, earthworms, ground and roverbeetles, millipedes, centipedes and the tree itself. Throw in a molesand voles, maybe a slightly pesky skunk, rabbits and the hawk they feed, robins who eat earthworms and a flicker who eats ants, and the orchard comes into focus as part of a whole ecosystem.
Happy growing! Because, after all, change is the only constant. -Xander Rose
A few useful resources:
Phillips, Michael. 2012. Chelsea Green Publishing Company: The Holisitic Orchard: Tree Fruits and Berries the Biological Way.
Poizner, Susan. “The Ultimate Guide to Fruit Tree Mulch” Accessed 12/15/2020: <https://orchardpeople.com/fruit-tree-mulch/>. (Also check out her podcast: “Orchard People”).
Poizner, Susan. "Episode 36: Willow Mulch for Fruit Trees" Orchard People podcast, with guest Dr. Glynn Percival of UK and Ireland Bartlett Tree Research and Diagnostic Laboratory. Accessed 12/15/2020: <https://orchardpeople.com/willow-mulch-for-fruit-trees/>.
UMass Extension. 2012. “ Mulching Tree Fruit and Small Fruit” Accessed 12/15/2020: https://ag.umass.edu/sites/ag.umass.edu/files/fact-sheets/pdf/mulching_fruit.pdf.