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Magnolias are well known for the mess they make with their leaves. Many gardeners hate having these due to the number of leaves that end up on the ground.
Often people wonder if magnolia leaves have a use in the garden or around the home. The question that is most often asked is do magnolia leaves make good mulch? And the answer is: it depends on what you are using the mulch for.
Magnolias are allelopathic. This means that they have a chemical in them that will release into the soil that prevents other plants from growing well or even not at all (2).
This is nature’s way of ensuring that nothing encroaches on the tree and allows it to grow well without competition in the area it needs.
Often people will notice nothing grows well under their magnolia trees, including grass. This is due to the allelopathy of the tree and the leaves that it drops.
Also, another distinct feature of magnolia leaves is that they are very thick and waxy. These features don’t make magnolia leaves fast decomposers. So even if they are on the ground they are not going to break down very well.
Can You Use Magnolia Leaves for Mulch?
Yes and no.
Magnolia leaves will work well as a mulch for a path or an area where you don’t want much growth of vegetation.
In fact, using them as a mulch can be a great way to control weed growth in areas where you don’t want anything to grow.
They don’t work well as a mulch for a garden or flowerbed. This is due to the allelopathic nature of magnolias.
Using them as a mulch in an area where you are trying to grow other plants will cause plants to die off, stunt growth, or not germinate at all.
A study was done and concluded that the chemicals from magnolia leaves inhibited root growth. reduced germination of seeds, and stunted plant growth (1, 3).
How to Make Mulch from Magnolia Leaves
With the leaves of magnolia trees, it is best to use a chipper to chop up the leaves to make them into a mulch.
You can use a wood chipper to do this. Or if you don’t have a wood chipper you can use a lawn mower to mow over the leaves until they are chopped up into a mulch.
Can You Compost Magnolia Leaves?
There are no definite conclusions that composting in the traditional way or composting with a tumbler will help reduce or get rid of the allelopathic chemicals from magnolia leaves.
If you are using either of these methods for composting it is best to keep magnolia leaves out of your garden compost.
However, there is evidence that vermicomposting will help turn allelopathic plant waste into usable organic matter for the garden (4).
So if you have vermicomposting, instead of a compost pile or tumbler, then you can use magnolia leaves in your compost.
When using the leaves in your vermicomposter make sure to cut the leaves up in a chipper or use a lawnmower to chop them up before adding them to your compost. The leaves are very thick and need to be chopped up prior to being added.
- (1). Raabe, Robert D. “Studies on Deleterious Effects of Decomposed Tree Leaves on Vegetable Seedlings”, http://webcache.googleusercontent.com/search?q=cache:A8pTrIyZuHoJ:slosson.ucdavis.edu/newsletters/Raabe_199129122.pdf+&cd=1&hl=en&ct=clnk&gl=us
- (2.) “Allelopathy”, http://csip.cornell.edu/Projects/CEIRP/AR/Allelopathy.htm
- (3.) Abdelgaleil, Samir A.M. “Allelopathic potential of two sesquiterpene lactones from Magnolia grandiflora L.”, https://www.sciencedirect.com/science/article/pii/S0305197807001482
- (4.) “Vermicomposting transforms allelopathic parthenium into a benign organic fertilizer”, https://www.sciencedirect.com/science/article/pii/S0301479716302535
- (5.) Thomas, Bob. “Allelopathy, Delta Journal, Times-Picayune, October 28, 2007, C-11”, https://lucec.loyno.edu/natural-history-writings/allelopathy