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Food for magnolia trees

Updated February 21, 2017

Before feeding your magnolia tree determine what it really needs. If your magnolia has healthy foliage and is gaining height and circumference, fertiliser is probably not necessary. For lacklustre magnolias, perform a soil test before fertilising.

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Basic Nutrients

Magnolia canopy and root growth require at least 18 nutrients, according to Hubert Conlon, Extension specialist at the University of Tennessee. Nitrogen, phosphorus and potassium (N, P, K) are the most commonly applied nutrients.


Magnolias responded to high-nitrogen slow-release fertiliser (20N-2P-8K) with more root growth and less canopy growth, in Tennessee growth trials. A more balanced formula of nitrogen to potassium (8N-3P-7K) applied monthly produced healthier magnolias.

Phosphorus, Potassium

Magnolias receiving 2 to 3 per cent phosphorus or potassium in the Tennessee growth trials were unaffected.

Organic Materials

Nutrient levels are lower and release-rates slower using organic material such as magnolia food. Manures have high N-P-K ratios are not recommended for magnolias. Cotton-seed meal is close to the University of Tennessee experts' recommended ratio. Composted sludge applied with commercial fertiliser produced even magnolia growth in the Tennessee Extension trials.

Compost Mulch

A study by the International Society of Arboriculture found that mulched magnolias surpassed unmulched trees in branch and canopy growth. Finished compost with known components used as mulch benefits by providing micronutrients as it is watered into the soil.

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About the Author

Beth Asher began writing in 1972 for a catalog company. She has written for schools and charities, including Star Workshop Foundation. She was a John Deere representative for nine years, manager of Brown's Blueberries and an advisory member of King County Small Farms Board and the Washington Association of Landscape Professionals. Asher holds a Bachelor of Science in computer networking from City University.

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