Most ornamental plants need nutrition. This is because they have different characteristics from wild plants, such as abundant flowering. Usually, such features require additional nutrition.
QUICK ANSWER: Fertilize magnolia in early spring. Use a slow-release granular fertilizer with an NPK ratio of 12-4-8. Apply fertilizer around the magnolia.
Read also: Basic Guide to Growing Healthy Magnolias.
When to fertilize?
The best time to apply slow-release fertilizer is March-April. Choose a fertilizer that lasts at least 3-4 months. In this case, the magnolia will be nourished for the entire growing season.
Do not apply the slow-release fertilizer later than the first half of summer. Especially don’t do it in the fall. This is because the magnolia can stay active through the winter and will definitely suffer frost damage.
How to fertilize?
Slow-release pellets with an NPK ratio of 12-4-8 are the best. That is, the product should contain more nitrogen than phosphorus and potassium.
Make sure the fertilizer contains at least some magnesium and iron. Also, the longer the action time of the pellets, the better.
Dig three small holes around the magnolia up to 2 inches deep at equal distances from each other. The distance between the holes and the trunk of the magnolia should be at least 0.5 feet but no further than the drip line of the tree.
Dig the holes very gently to avoid damaging the root system.
Take the amount of fertilizer recommended by the manufacturer and spread it evenly between the holes. Cover the holes with soil.
Next, water the magnolia with 1-2 gallons or more. Nothing more is required of you; the pellets will work all season long.
Natural fertilizer
In addition to mineral fertilizer, you can also use organic fertilizer. Both can be applied together without any negative consequences.
Compost works best among the whole range of organic matter used as fertilizer. The main thing is that it should be of high quality and free from pests and pathogens. To get this quality, buy this product only from reliable suppliers.
The first time, compost should be applied to the planting hole before planting the magnolia. Mix 1-2 buckets of compost with the native soil in the planting hole.
After planting, mulch the root zone with a 2-3 inch layer of compost. Do not put mulch on the trunk of the magnolia; avoid so-called volcano mulching.
Every year in the spring, the compost mulch should be renewed.
Fertilizer burn
Over-fertilization is possible if fertilizer is applied too often or in too large portions. This will result in salt accumulation in the soil, causing damage to the root system.
The outward sign of excess minerals is a browning of the leaves. This usually occurs along the edge of the leaf.
Water the magnolia with 5 to 6 gallons of water to remedy the situation. This will flush out some of the salts from the root zone. Repeat this watering after 1 to 2 weeks.
Also, replace the top 1-2 inches of soil around the roots if possible. Be as careful as possible not to damage the roots.
From now on, fertilize the magnolia no more than twice a year. The last fertilization of the year should be done no later than mid-summer.
Not enough nutrients
If your soil is more or less nutritious, the magnolia should not be deficient in nutrients even if you do not fertilize it. However, there are cases where the tree will suffer without fertilization.
The first is poor sandy or clay soil. The magnolia may not have enough minerals here and will grow very slowly.
In this case, you should improve the soil with organic matter before planting. Also, the magnolia should be fertilized at least once a year.
The second case of fertilization deficiencies is when the soil is too alkaline. If the pH>7.0, the nitrogen may not be available to the root system. As a result, the leaves will turn yellow.
To remedy this, buy a soil pH test kit and find out what kind of soil you have. If the soil is too alkaline (pH>7.0) acidify it with garden sulfur or other commercially available acidifiers. Then, follow the fertilizer recommendations above.
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