Most magnolias - with the exception of the evergreen magnolia - shed their leaves in the fall, which, like other deciduous trees, have previously changed color. However, if the yellowing of the leaves does not occur in autumn, but in the middle of summer or even in spring, then chlorosis is present.
Causes of Chlorosis
Chlorosis always indicates a deficiency, usually of the two essential nutrients magnesium (Mg) and iron (Fe). Acidic, firm soils, such as those preferred by magnolias, are often poor in magnesium - especially since this nutrient is either far too low in doses in most commercially available fertilizers or is even not present at all. In addition, soil that is too compacted can prevent the plant from absorbing nutrients.
treat chlorosis
As a first step, you should loosen the soil in the root area. Be careful not to damage the roots of the flat-rooted magnolia. Work as deep as you can, digging in some topsoil or compost. You should then fertilize the plant with magnesium and/or iron.
tips and tricks
If there is a severe magnesium deficiency, fertilizing with a 2 to 4% Epsom salt solution will quickly remedy the situation.