How do you properly fertilize trees?

Table of Contents:

• Reasons to fertilize a tree
• Healthy soil: the basis for tree growth
• Have a soil sample taken
• Provide the tree with the necessary nutrients
• Which trees need additional nutrients?
• How do I recognize a nutrient deficiency in my tree?
• How do you properly fertilize trees?
• Organic fertilizer vs. mineral fertilizer
• Fertilizing and watering: Supplying the tree with nutrients and water
• Mulching as a natural soil improvement
• Make your own compost
• Storing biochar
• Use tree watering bags and fertilize trees.
• The tree bath worm compost tree fertilizer

Fertilizing can increase soil fertility and thus promote healthy growth for your tree. And not only that: fertilizing can improve the soil and enhance soil life. On a small scale, it also helps to store carbon in the soil. 

And yet, it's not quite that simple. Not all fertilization is beneficial. Some soils are already over-fertilized. And some fertilizers can do more harm than good. Let's take a closer look:

Reasons to fertilize a tree

If you're considering fertilizing your trees, it's helpful to first determine your reasons for wanting to do so. Different motivations require different approaches and methods. Here are the most common reasons for fertilizing a tree:

• Correction of an acute nutrient deficiency
• Improvement of soil structure and humus content
• Enrichment of soil life 
• Long-term storage of carbon in the soil

To remedy an acute nutrient deficiency, you can use targeted fertilizers. Mulch, compost, and organic fertilizers are suitable for sustainable soil building and enriching soil life.
You can add biochar to the soil for the long-term storage of carbon and the improvement of the soil's capacity to retain water and nutrients.

Short-term nutrient addition and long-term soil improvement are not the same and should therefore be considered separately. 

And then there are also methods that cover all three goals simultaneously. But let's start at the basics: the ground. 

Healthy soil: the basis for tree growth

Healthy soil is an essential prerequisite for healthy trees. The federal government's definition of soil is:

"Soil is the product of the transformation of mineral and organic substances, permeated with water, air and living organisms, created under the influence of environmental factors on the earth's surface and evolving over time, with its own morphological organization, which is capable of serving as a habitat for higher plants. This enables soil to form a basis for life for animals and humans."

Here are the most important functions of the soil:

• The soil, with its mixture of nutrients, fungal networks, water and microorganisms, forms the basis for plants to grow and thrive. 
• The soil represents a kind of microcosm in which countless living beings share a habitat, from bacteria and other tiny organisms to small animals.
• The soil also acts as a kind of filter for the percolating rainwater, which becomes increasingly cleaner groundwater on its way down, and in many places thus achieves drinking water quality. 
• Vast amounts of carbon are stored in the soil. 

Have a soil sample taken

Since most of us cannot easily determine soil quality simply by looking at it, it can be worthwhile to have a soil sample taken. Because: When you fertilize the soil, you're interfering with a complex process and can potentially cause damage. Many soils are already over-fertilized, especially with nitrogen and phosphate. If you add even more of these through unbalanced fertilization, the natural system may become even more unbalanced, which can also negatively affect the trees.

A soil analysis usually also includes receiving specific tips on optimal fertilization. Furthermore, you will receive additional information about pH value of your soil.

If you want to do without a soil test, we recommend organic fertilizers, mulch, or Worm compost to use. This will bring you closest to the natural nutrient cycle.

Provide the tree with the necessary nutrients

Nutrients are essential for healthy tree growth. A lack of nutrients, or deficiencies, usually manifests as leaf discoloration, stunted growth, reduced yields, and even acute tree diseases. 

Because trees are resilient and long-lived organisms, they can initially survive extended periods of nutrient deficiency without it becoming apparent how severely they are suffering. It is important to understand, however, that weakened trees are significantly more susceptible to all kinds of stress than those with a balanced nutrient supply.

The main nutrients for trees include nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), and calcium (Ca). In addition, there are a number of trace elements that are essential for healthy metabolism and growth, of which a tree only needs small amounts. This group includes iron (Fe), copper (Cu), boron (B), zinc (Zn), molybdenum (Mo), silicon (Si), and manganese (Mn). Ideally, these nutrients should be available in sufficient quantities in the soil for the tree to absorb.

Important: Nutrient deficiencies can arise not only from a lack of fertilizer but also from an unbalanced nutrient supply. Therefore, we recommend determining in advance which nutrients your soil requires. This is especially important if you are using commercially produced fertilizers. If you only use organic fertilizers (such as your own compost, mulch, or plant-based fertilizer), an unbalanced nutrient supply is much less likely. 

For example, a very high potassium content in the soil can impair magnesium uptake by the roots, even if sufficient magnesium is actually present. Such interactions (antagonisms) are a common cause of hidden deficiency symptoms.

It's also important to note that each tree species has different needs. We therefore recommend that you research the specific requirements of your trees.

Which trees need additional nutrients?

Generally speaking, many trees do not require any additional nutrients. However, there are exceptions:

• Trees growing on barren, nutrient-poor soils
• Fruit trees that are expected to consistently produce a high yield over a long period of time
• In very well-maintained gardens or parks, where, for example, autumn leaves are removed immediately and thus no longer serve as natural fertilizer.
• For young trees that were planted several years ago without soil improvement
• When a tree shows signs of nutrient deficiency

In these cases, it makes sense to optimize the nutrient balance of the soil by regularly using organic fertilizer and mulch in order to create a healthy, growth-promoting environment for trees.

How do I recognize a nutrient deficiency in my tree?

Typical signs of nutrient deficiency include:

• Leaf whitening or yellowing
• Premature leaf drop
• Weak or absent flowering
• Low fruit set
• Reduced growth

These signs are also similar to those of the so-called Drought stressTherefore, as a first step, it might be helpful to simply provide the tree with sufficient water. 

How do you properly fertilize trees?

Here are the most important guidelines for fertilizing trees:

• Don't use fertilizer carelessly; ideally, have a soil sample tested beforehand. This is especially important if you're buying commercially produced fertilizer. 
• Apply fertilizer preferably in spring (March to May) at the beginning of the growing season, as the trees have the highest nutrient requirements for growth and bud break at this time. 
• Avoid applying fertilizers with a high nitrogen content in late summer and autumn.
• Use organic fertilizers whenever possible, as these also contribute to improving soil quality.
  
• Use mineral fertilizers sparingly and bear in mind that although they contain the main nutrients NPK, they do not contribute to soil improvement and can even be harmful if used excessively.
  
• Adjust fertilization to the tree species, location, and soil condition.

Keep in mind that different tree species have different nutrient requirements. Fertilization should always be tailored to the specific type of tree and its environment. Generally speaking, good soil structure and active soil life are more important in the long run than short-term nutrient applications. Sustainable soil improvement through compost and mulching is more effective over time than repeatedly applying individual nutrients in the form of artificial fertilizers.

If you want to fertilize your tree, you can follow these steps:

• First, check the condition of the soil: If it is dry or heavily compacted, we recommend watering it first. 
• Apply the fertilizer to the outer crown area. That's where most of the tree's fine roots are located.
• Avoid applying fertilizer directly to the trunk.
• Then thoroughly water the area so that the nutrients reach the root zone.
  

You can find more information about seasonal special features in the text. Trees fertilize themselves in the cycle of the seasons.

Organic fertilizer vs. mineral fertilizer

Basically, there are two types of fertilizer: organic and mineral fertilizer. Organic fertilizer is produced by the slow decomposition of organic matter, for example through composting or Worm compost. 

Organic fertilization increases the amount of humus, improves the soil and improves soil life. Organic fertilizers not only contain individual elements such as nitrogen, but usually a whole range of important nutrients and trace elements that a tree needs.

Mineral fertilizers, on the other hand, are mostly designed for specific nutrients, which are mainly based on nitrogen, phosphorus and potassium, and are therefore also called NPK fertilizers.

Important: Mineral fertilizers should be used with more caution than organic fertilizers. With organic fertilizers, it is much more difficult to achieve one-sided over-fertilization than with mineral fertilizers.

We recommend the following as an organic fertilizer: Baumbad liquid fertilizer made from worm compostIt In addition to important plant-available substances, it also contains humic acids and living microorganisms that further enrich the soil life. 

Fertilizing and watering: Supplying the tree with nutrients and water

Both nutrients and water are essential for a tree's health and growth. If a tree shows deficiency symptoms, it could be due to either a nutrient or water deficiency; the tree often displays the same symptoms. Therefore, if you observe deficiency symptoms, we recommend first checking whether the tree might be getting too little water.

Furthermore, water is essential for trees to absorb and metabolize nutrients in the soil. When considering fertilizing trees, we recommend always thinking about irrigation as well. This is especially important during dry periods. 

Mulching as a natural soil improvement

Mulching is a word often only known to gardeners. Unfairly so, because it's something very simple and essentially just follows a principle from nature. In forests, for example, the soil is covered with a layer of leaves and fallen branches.

Mulching is the process of covering the soil with plant material. It is a simple and effective method for improving soil quality.
The slow weathering of the various organic materials in the mulch layer provides the soil life below with nutrients and carbon, while at the same time covering the entire soil and thus protecting it from drying out.

Mulching offers you, among other things, the following advantages:

• It slowly and steadily delivers carbon and other important nutrients to the soil, thus building it up.
• Provides food for soil organisms
• Promotes the favourable crumb structure of the soil. This also allows the soil to absorb water better
• Protects the soil from drying out and thus ensures even soil moisture.
• Suppresses the growth of other plants (including so-called weeds)
• Prevents surface soil erosion (leaching of nutrients)

What materials can you use for mulching?

• Laub
• grass clippings
• shredded bark material 
• semi-mature compost covered with a thin layer of organic material
• chopped straw
• wood shavings or wood chips

How to use mulch:

• Green material is only applied thinly, otherwise it will easily rot. It can be renewed more often
• Dry material can be applied in a thickness of 5 to 10 cm.
• Heavy soils (very clayey and loamy) should be mulched with as much "loose" material as possible, otherwise the risk of waterlogging and rot is increased.

In this article you will find more information about the Mulching trees. 

Make your own compost

You create a compost heap for the entire garden ecosystem. This promotes local biodiversity, improves the soil, and stores carbon in the earth. At the same time, you reduce kitchen waste by returning some of it to the soil. 

If you have enough space in your garden, we definitely recommend creating your own compost heap. You can then use the mature compost to fertilize your trees. This article provides the most important information about composting. composting. 

Storing biochar

Due to its porous structure  biochar It has a large surface area, which allows it to store water and nutrients particularly well. Similar to a sponge, it is able to retain water and store nutrients. It also provides a habitat for microorganisms in the soil. Furthermore, by incorporating biochar into the soil, you can also benefit from its ability to absorb nutrients in a small amount of water.ßThey help to store carbon in the soil. 

Before incorporating the biochar into the soil, it's advisable to first saturate it with nutrients and water in a liquid fertilizer to ensure that the nutrients already present in the soil aren't absorbed by the biochar first. Worm compost-based liquid fertilizer is particularly suitable for this purpose because, in addition to nutrients, it also introduces a wealth of minerals and microorganisms into the biochar, thus providing a double benefit to your garden. You can find more information in the article. Biochar and worm compost: A power duo.

Use tree watering bags and fertilize trees.

Tree watering bags Tree watering bags are a suitable tool for efficiently watering trees. The water is released drop by drop into the soil, allowing it to seep into deeper layers where the tree can absorb it. A consistent water supply from tree watering bags can also improve nutrient uptake, as the soil remains moist more continuously.

You should keep the following points in mind when fertilizing trees and using tree watering bags:

• Use only liquid fertilizer that does not damage the material of the tree bag.
• Do not put any solid items in the bag (risk of blockage).
• Avoid liquid manure or fertilizer teas containing suspended particles. in the bag
  

If you want to water your tree with a tree bag and simultaneously supply the soil with nutrients and microorganisms, we recommend the tree bath. Liquid fertilizer made from worm compost to add to the watering can.

The tree bath worm compost tree fertilizer

If you'd also like to know when fertilization is particularly beneficial during the year, read our article. Trees fertilize themselves in the cycle of the seasons..