Comments on: Chipped Eucalyptus Wood and Leaves from Tree Trimmers

By: Pat

Pat — Wed, 02 May 2012 05:22:49 +0000

I read over your question twice to try to understand it. It seems as if you are asking me this question: Will mulching vegetables with eucalyptus and pine needles harm your vegetables? The answer is no, as long as you are just using these materials on top of the ground as mulch. (If that is not your question, you need to phrase it better.) A second part of your question seems to be will these ingredients in your mulch harm soil as they break down? The answer is No, but you must wait until they are fully rotted before you dig them into soil as soil amendment and that will take a very long time, perhaps years for the eucalyptus leaves. Pine needles are acidic and somewhat slow to rot. Eucalyptus leaves are oily and highly resistant to rotting, but they are no more acidic than anything else. So as you can see, both pine needles and eucalyptus are very slow to rot. They will not rot while lying on top of the ground in your vegetable garden for one season as mulch unless you grind them up into small pieces first. The important rule for you to follow is not to dig eucalyptus leaves or pine needles into the ground until they rot on top of the ground, and that is unlikely to happen this year. Thus you are fine. However, there is a very important rule for you to follow. Do NOT dig these un-rotted materials into the ground until they have fully rotted. You will know when that happens since then you will not be able to tell what they once were. This means that you must pull back the mulch before pulling out a spent crop such as the root of a cauliflower after you have harvested the head. Then you should amend the soil with compost and mix in fertilizer and plant something else, such as an eggplant in that space. After which you can replace the mulch. If you allow un-rotted carbonaceous materials such as eucalyptus leaves or pine needles to be buried in soil they will rob nitrogen from the soil in order to rot, as I have said many times. But as long as they lie on top of the ground they will do no harm whatsoever. Pine needles make an excellent path covering in vegetable gardens. I have often used them that way in mine and once they had fully rotted then it’s okay to dig them into the ground as additional soil amendment since they do no harm once fully rotted. Also, their acid composition didn’t harm my soil either since our soils in the west are alkaline and our irrigation water is alkaline also, so adding some acid organic materials is a constructive thing to do. Mainly, however, I have used pine needles from my trees as mulch around azaleas and camellias since azaleas and camellias are acid-loving plants.

By: Maria

Maria — Wed, 02 May 2012 00:22:43 +0000

I just need to confirm that I understand this well, I have mulched my entire veggie garden with about 5in of eucalyptus and pine mulch as I was inspired by this gardening DVD I watched. I didn’t realise that his advise was that you can mulch just about any tree but eucalyptus as it is very acidic. Can I safely leave the mulch there and what are the long term effects as it starts to breakdown into to soil. Thank you

By: Pat

Pat — Tue, 27 Sep 2011 04:47:13 +0000

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.

By: holly blackwood

holly blackwood — Tue, 27 Sep 2011 00:08:09 +0000

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.