Contrary to public opinion, there is absolutely nothing wrong with using the contents of tree-trimmers chippers as mulch, even if the source is eucalyptus. All wood eventually rots and becomes part of the soil. Eucalyptus chippings make an excellent and low cost mulch. Not only does it often come free of charge, but also it is clean. It contains no weed seeds and it is highly unlikely to contain pesticides or herbicides which may not be true of mulch from other sources. Many folks suppose that eucalyptus wood or leaves will kill plants, but this is entirely untrue. The only time when wood chips or chopped leaves of any species, including eucalyptus, can kill plants is when folks unthinkingly dig these raw un-rotted materials into the ground. This practice can turn plant leaves yellow and may kill them because un-rotted wood will rob soil of nitrogen in order to rot and thus also rob nitrogen from plants. This will happen regardless of the source of the chipped wood or leaves. If you do not dig the chips into the ground but just let them lie on top as mulch, no harm is done. So definitely do not remove the mulch. Next fall you can put a layer of manure right on top as described below under clay soil. Just don’t dig it into the ground.
The only wood products that can be used safely as soil amendment, in other words dug into the ground, are products that have been fully nitrolized (i.e.: enough nitrogen has been added to them so they can rot) or, alternatively, they have been fully composted, which means largely rotted. So the answer to your question is that your trees will be fine with raw chipped eucalyptus wood and leafy products on top of the ground as mulch where they will slowly decompose and add goodness to the soil. Meanwhile, this eucalyptus mulch will greatly reduce the growth of weeds and help to hold moisture in the ground. (See page 29 In my new organic book for the exact amounts of nitrogen to add to raw shavings to make them safe.) No addiltional nitrogen needs to be added when using the chips only as mulch.
Related Articles:
- Problems with Unrotted Wood Products in Soil
- Vegetables in Raised Beds: Problems with Yellow Leaves
- Vegetables, Eucalyptus, Clay Soil, and Fruit Trees
- Do Not Dig Chipper Materials into the Ground
- Eucalyptus Trees
I used eucalyptus chippings on top of a new lasagna type bed in a field where I’m planning to grow native california bunching grasses, lavenders, cleveland sage, kniphofias, matilija poppies and other deerproof plants. I was starting to rake it off but now after I read this article I’ll just rake it away from the planting holes when I plant next month. Should be o.k.? I put chicken manure down followed by cardboard to smother the grass, soil, then eucalyptus chips.
Yes, simply rake the wood chips away when you plant so they don’t get into the ground. Chipped wood mulch is fine on top of the ground as mulch where it gradually decomposes (rots) and becomes part of the soil through time. Think of the north woods where leaves fall, twigs and branches fall and rot and gradually it all becomes soil and once it rots it then gives off nitrogen that the tree roots can then pick up as food. Thus in a sense a tree can grow in a forest on its own refuse. The same is true in gardens. We only need to remember not to dig this dry stuff (wood chips and any uncomposted, unrotted organic mulch) into the soil. If we dig it into the soil it then subtracts nitrogen from the soil in order to rot and this can kill plants. If mulch (wood chips, dried leaves, whatever) lies on top of the ground it cannot rob the soil of nitrogen and this has no affect on the plants. So, yes, you are okay to plant in your lasagna garden as long as you do not combine the un-rotted woody layers (in this case eucalyptus chips) with the layers in which plant roots are going to grow because if you do large amounts of nitrogen will be subtracted. If accidentally some chips get into the soil, you could add blood meal to compensate or any other source of nitrogen but it’s difficult to balance the amounts just right without burning roots, especially in an airy lasagna garden. Spoiled hay can also be used as mulch instead of chips as most books on this kind of gardening often suggest. Hay rots quickly and is a strong source of nitrogen and of course spoiled alfalfa is especially good. Horse owners are a source of this since the flakes of alfalfa drip stuff onto the floor and you cannot feed a horse with spoiled alfalfa if it is even slightly mildewed or your horse will fall ill. I also would like to mention that the water needs of the plants you mention may vary from one another. Red hot pokers (Kniphofias) are supposed to be drought-resistant but my experience with them is they need good drainage or they will sicken and die, but they also require plentiful irrigation in summer when they are flowering or they won’t ever bloom. In winter they can go dry but that’s when we have our heavy rains. I have not had much luck with kniphofias in Mediterranean climates, but they grow wonderfully in England and there they are considered “drought resistant”. They look as if they should be drought resistant but my opinion is that here they aren’t except in winter. So go figure! (I realize this is an opinionated comment and would be happy to hear from other gardeners on this point). Personally, I do not find kniphofias easy to grow in coastal zones of Southern California and wonder why they are so often touted as good things to grow when I don’t see any good ones in gardens? If one lives in Southern California I think Kangaroo paws (Anigozanthus) are a better choice since they bloom like mad and are perfectly adapted to our climate. They are not exactly the same shape, which loss I deplore, but kangaroo paws do point upwards with drama and decision and they come in lovely colors, bloom all summer with little care and are truly drought tolerant. Additionally, aloes come in many forms and all have spiky flowers similar to red hot pokers. Bloom of each species is brief but there are so many varieties to choose from you can have some in bloom all year.