The adornment of a magnolia tree are the large, pink flowers in spring. The green leaves, which sprout a little later, are inconspicuous companions. In autumn they turn yellow and detach from the tree. But the yellowing must not happen at an earlier point in time! You don't have to look far for the cause. A nutrient deficiency is usually responsible for this. But the magnolia can recover.
Pay attention to the timing of the discoloration
The fall of leaves in autumn is not entirely correct, because both evergreen magnolias and deciduous varieties are cultivated in this country. The evergreen specimens are planted in mild regions of the country or in tubs because they are sensitive to frost. They keep their foliage all year round. Excessive yellow leaves are therefore a cause for concern, regardless of the season. With deciduous varieties, yellow leaves are only safe in the fall. In summer or even spring, they are a sign that something is wrong with the tree.
Plant disease chlorosis
Yellow leaves on magnolia are symptoms of a plant disease called chlorosis. It is also known among gardeners as jaundice or chlorosis. Photosynthesis in the leaves of the plant is disrupted. New chlorophyll cannot be formed, existing ones are broken down. However, chlorophyll is the substance that gives the leaves their rich green color. The less of it there is in them, the yellower they become. Yellowing of the leaves is not the only consequence of chlorosis. If you do not find a solution to the causes of this disease, the following effects are added:
- leaf shedding
- poor growth
- cessation of growth follows
- eventually the plant dies
triggers of chlorosis
In order for you to stop magnolia suffering, you need to know what caused the chlorosis. Thankfully, it's not a hard-to-control fungal disease, just a lack of nutrients. In most cases, when the leaves turn yellow, the magnolia lacks iron (Fe), but occasionally the supply of magnesium (Mg) can also be insufficient. Both elements are essential for chlorophyll formation.
lean soil
The roots of the magnolia tree may not find enough of these two nutrients in the soil. This is even more likely if you got the optimal location when planting. This tree prefers acidic and solid soil. However, what their owner needs to know is that such soil is poor in iron and magnesium. If the poor soil meets insufficient fertilization, an undetected undersupply can quickly occur. After all, the correct interpretation of the yellowness can open the eyes and pave the way to the solution.
Magnolia with slight chlorosis
Tip: Water the lime-sensitive plant with soft rainwater to keep the pH in the preferred low range of 5.5 to 6.8. This enables this tree to absorb nutrients well.
compacted soil
Sometimes it can also happen that both elements are present in sufficient quantities in the soil and yet yellow leaves appear on the magnolia. Then the absorption of nutrients will probably be disturbed. Compacted soil inhibits root growth and also makes good root penetration in the soil more difficult. In addition, compacted soil tends to waterlogging, which can also damage the root system. But only intact roots can absorb enough nutrients from the soil.
Wrong fertilizer
While soil is not inherently poor in nutrients, it still needs to be replenished from time to time to compensate for the magnolia's consumption. But fertilizer is not just fertilizer. If you buy the magnolia fertilizer from the trade, it is high time to read the small print on the packaging. How high is the proportion of iron and magnesium? Many fertilizers include these two elements in modest doses or leave them out altogether.
countermeasures
Ultimately, it is not unlikely that there is a combination of two or all three causes. The easiest way to spot compacted soil and the nutrient composition of a fertilizer is to look closely. The nutrient content of the soil is not readily visible. However, you have the option of having an inexpensive soil analysis carried out. For this you have to send soil samples to an analysis laboratory and wait a few days for the result. Measures that you can use to combat chlorosis are described below.
loosen soil
Even before you reach for the fertilizer, you should first loosen the soil. If the soil is too compacted, this can be difficult. Nevertheless, care must be taken not to damage the root system. The magnolia is flat-rooted. Their roots do not go deep into the earth, but are near the surface of the earth. Don't stay close to the trunk, but fluff up the entire area below the crown.
fertilize soil
Based on the severity of the disease symptoms and the values of the soil analysis, the ideal fertilizer or dosage must be selected. If the leaf coloring is not very advanced, it may be sufficient to work in plenty of humus and compost after loosening the soil. If necessary, you can then supply the plant with a fertilizer containing iron and magnesium.
Epsom salt
Notice: If the magnesium deficiency is severe, the solution is to immediately supply Epsom salt.
prevent chlorosis
So that chlorosis does not strike again, the iron and magnesium values must remain in the green range in the future. On the other hand, it should not be fertilized generously, because over-fertilization is not good for this plant either. A magnolia is content with rotting compost in the spring and fall. Only tub specimens require more extensive nutrient supply. If you use a commercial fertilizer as a fertilizer, it must contain iron and magnesium. In addition, there should be extra doses of iron and magnesium only once the magnolia tree begins to change leaf color unexpectedly towards yellow.
Tip: Fertilize the magnolia with a rhododendron fertilizer. Both plants have similar soil requirements. They like it sour and hate lime.