In general, apple trees are among the more easy-care specimens, even among fruit trees. However, in order to have a rich apple harvest, you should not forget to supply the tree with sufficient nutrients.
How and when should you fertilize an apple tree?
Apple trees require moderate fertilization with nutrients such as nitrogen and potash. Young trees should be provided with compost and manure, while older trees receive complete fertilizers containing potassium or organic-mineral fertilizers. Fertilization takes place twice a year, in spring and late summer.
Fertilize freshly planted apple trees properly
Basically, many hobby gardeners tend to over-fertilize the fruit trees in the garden rather than supplying them with a lack of nutrients. That's why all fertilizer applications should be administered sparingly. For a freshly planted apple tree, it is usually sufficient for the first two to three years in the new location if the excavated soil around the tree roots was mixed with compost and stored manure during planting. Only then should around 10 grams of blue grain (€12.00 on Amazon) be administered per tree around the trunk in spring and late summer. Over-fertilization with nitrogen would pose the following dangers to the apple tree:
- immature, dying branches in winter
- strong shoot growth at the expense of flowers and fruits
- increased susceptibility to diseases and pests
The effective fertilization of older apple trees
Depending on their variety and location, older apple trees usually have a slightly higher nutrient requirement than their younger relatives. First of all, a larger tree disc around the tree trunk should be covered with mulch in summer to protect it from drying out. Ideally, for large apple trees with full yields, you should use a complete fertilizer containing potassium or an organic-mineral fertilizer. Apply about 60 grams of this per tree twice a year, once in March and once around the middle of the month in May. However, if you have fresh compost available, you can also distribute around four liters of it on the tree disc in spring. After a soil test, you may be able to supplement it with horn meal and lime ammonium nitrate.
Underplanting with green manure
The use of chemical fertilizers can also be avoided on apple trees if, in addition to the annual incorporation of compost into the soil in the area of the tree disk, green manure is also planted underneath. Plants such as low-growing nasturtiums or lemon balm are suitable for this and are then incorporated into the substrate after the season. This naturally creates rotting material that protects the delicate roots of the apple tree and supplies it with moderate amounts of nitrogen and other nutrients.
Tips & Tricks
For young apple trees, no freshly chopped wood parts should be added to the soil when mulching, otherwise these would remove nitrogen from the soil during the rotting process. Older trees are less sensitive and their tree slabs can also be covered with wood-containing materials. In general, proportionate fertilization should ensure a balanced ratio of fruit yield and shoot growth. Fertilization should be avoided in late autumn, otherwise young shoots will not survive the frosty temperatures in autumn and early winter.