There are many different approaches to mulch, with some people swearing by it, and others rarely or never using it or recommending it. We tend to be in the latter camp.
Our fruit growing study tour of the USA last year got us thinking slightly differently about mulch, as we saw a number of different approaches to it in our travels.
Sadly but unsurprisingly, it’s not hard to find orchards where the weeds have been completely sprayed out with herbicide, and mulch isn’t needed because there’s no plants left to suppress. In fact, in most orchards around the world that is still considered to be best practise.
Yuk! Please don’t do that to your fruit trees. It’s an approach we moved away from in our orchard many years ago.
The chemicals are bad for your health, the weeds grow back and need spraying again (which is money straight from your pocket to the chemical companies), but worst of all – it’s really bad for the soil and kills the natural fertility system that trees need to get their nutrients (more money from your pocket, to the fertiliser company).
So, what to do? Should you just let the weeds grow? Won’t they compete with the trees? For young trees this is somewhat true – it’s definitely helpful to keep the weeds (or you could call them precious understory biodiversity plants) down while the tree’s roots are getting established. We’ve always weeded around the very young trees in our on-farm fruit tree nursery, but these days are moving towards using woody mulch around the trees.
We also saw this in action at the Maine Heritage Orchard in Unity, Maine. This orchard was planted not that many years ago on the site of a disused gravel pit, so major soil building and remediation has been the order of the day.
Hardwood chips have been extensively used, not only to mulch the trees when they were planted, but also to build paths, build soil more generally, and as an ongoing weed suppression tool even as the trees mature.
We saw a different approach in Michael Phillips’ orchard in New Hampshire. Michael is author of The Apple Grower: A Guide for the Organic Orchardist, and we were lucky enough to be able to visit, spend some time with Michael and have a tour of his orchard. He also uses woodchips on young trees, but welcomes a wide diversity of understory plants as the trees grow, using mulch in a more ad hoc way.
There is widespread agreement that if you are going to mulch, hardwood woodchips are preferable. This is because fruit trees prefer a fungally dominant soil, as we explain in our Soil Biology and the Soil Food Web short course.
Understanding the amazing world of soil microbes that are key to the Natural Fertility System will change the way you think about soil, fertiliser and mulch forever.
So, to mulch, or not to mulch?
After everything we’ve seen, we’re still in favour of mulching while the trees are young, and then transitioning to either a natural or cultivated understory – a “living mulch”!
Hi guys, just wondering if you have any idea whether Eucalyptus wood chips can be used successfully as a mulch?
Thanks Vanessa
Hi Vanessa, yes eucalyptus mulch is fine but it should be aged first for a couple of reasons. The first is to give the volatile oils a chance to gas off, and the other is that fresh mulch can rob the soil of nitrogen.
Hi Katie, roughly how long would you age the eucy mulch?
Hi Stuart,
Good to age eucy mulch for 3 months+. It should lose that fresh green look and be looking grey and old rather than green and fresh.
Hi Katie, have you used eucalypt mulch in your orchard? Keen to hear if there are any long term negative effects on soil Biology. I have always turned down such mulch in favour of white wood deciduous such as willow, alder, birch etc. Thankyou!
Hi Michelle, some eucy mulch is fine, and if you dig about under any mature gum tree in the bush you’ll find that the understorey breaks down nicely and fungal growth is plentiful (in fact we use this as source material to brew a nice fungally-dominant compost tea). So it depends how you’re planning to use the mulch – if you’re thinking of complete mulch cover and maintaining the cover for more than one season then the willow etc. is probably better. In the orchard, we’re more in favour of occasional use in piles here and there (the method recommended by Michael Phillips), in which case using some eucy mulch will encourage fungal growth just fine.
I am curious to know what you would include as living understory for your mature fruit trees?
Great question Deborah, there’s such a long potential list of plants we won’t go into them here, but this is a topic we explore in in-depth in several different resources.
We’d highly recommend you have a look at “The ‘Under Story’ Masterclass” by Dr. Christine Jones – https://growgreatfruit.com/product/the-under-story-masterclass/. Also our “Guide to Edible Flowering Plants” (https://growgreatfruit.com/product/guide-to-edible-flowering-plants/), or “Build Soil Fertility with Green Manures” (https://growgreatfruit.com/product/develop-your-green-thumb/) all have plant lists.