Mulching trees

Mulching is a simple, inexpensive and effective way to do something good for your tree. But what is mulching anyway? And what do you need to take into account?

Mulching trees: The most important points at a glance

• Mulch reduces water loss and protects against drying out.
• Mulch improves soil structure and activates soil life.
• Do not place mulch directly against the trunk and do not apply it too thickly.
• especially effective before heat waves or in late spring
  

Table of Contents

• What is mulching?
• Advantages of mulch
• Suitable materials
• When mulching is not advisable
• How to properly mulch trees (instructions)
• How often should you mulch?
• Renew the mulch or leave it as is.
• Mulching for young and old trees
• Mulching throughout the year
• Mulching vs. Fertilizing
• Combine mulching and irrigation
• Avoid common mistakes
• Conclusion

What exactly is mulching?

Mulching is covering the soil with organic material. This technique is based on nature. In nature, you hardly ever see bare soil. Fertile soil is either covered with vegetation or covered with a layer of organic matter. In the forest, for example, the soil is covered with leaves, needles and branches. A layer of mulch protects the soil like a coat from Drying out, extreme heating or cooling and erosion. At the same time, a layer of mulch also protects soil organisms and supplies nutrients.

What are the benefits of mulching trees?

A layer of mulch…

• slowly and steadily supplies nutrients to the soil and thus builds it up
• promotes the favorable crumb structure of the soil.
• The crumb structure allows the soil to absorb water better
• protects the soil from drying out and keeps it moist
• regulates soil moisture and temperature
• suppresses the growth of other plants
• reduces erosion
• provides food and good conditions for soil organisms
• Occasional mulching can often eliminate the need for additional fertilizer

Which materials are suitable for mulching trees?

Many materials from the garden are well-suited for mulching. The most important thing is that they are organic and decompose over time. Here are the most important examples:

• Laub
• (dried) grass clippings
• Bark material or wood chips (e.g. from tree or hedge trimmings)
• semi-mature compost covered with a thin layer of organic material
• old hay
• chopped straw
• Nettles or other medicinal wild herbs

When should you not mulch trees?

Mulching is beneficial in many cases, but not always. Under certain conditions, a layer of mulch can even harm the soil:

• On very heavy, clay soils that are already prone to waterlogging, mulch can further reduce oxygen penetration into the soil. In such cases, moisture remains in the top layer for too long, which can promote rotting processes.
• Even in heavily compacted soils, mulching alone is often insufficient. If water can barely penetrate the soil, a layer of mulch will do little good. In such cases, the soil should first be carefully loosened to improve water and air circulation.
• Another point to consider is pests. Especially with existing vole problems, a thick layer of mulch can offer additional protection and exacerbate the situation. In such cases, it's advisable to keep the area around the tree relatively bare or to mulch very sparingly.
• Fresh grass clippings should also be used with care. In thick layers, they can quickly rot, leading to unpleasant odors and an unfavorable soil environment.

Preparing the soil: The basis for effective mulching

For mulch to be fully effective, the condition of the soil plays a crucial role. If the soil is heavily compacted or dried out, water cannot penetrate it properly. In this case, the effect of the mulch layer remains limited, as it protects the surface but prevents water from reaching the root zone.

It is therefore advisable to briefly prepare the tree base before mulching:

• Remove weeds and coarse plant debris.
• Carefully loosen the top layer of soil if it is very hard.
• Water the soil lightly in very dry conditions.

This ensures that water is absorbed better and that the mulch layer optimally fulfills its function.

How do you mulch trees properly?

For mulch to be fully effective, it's not just the material that matters, but also the correct application. With a few simple steps, you can optimally support your tree:

• First, you should prepare the area around the tree. Remove weeds and loosen the soil slightly if it's hard. In very dry conditions, it can be helpful to lightly moisten the soil beforehand so that the water is absorbed better later.
• Next, spread the mulch evenly around the base of the tree. Make sure to lay the mulch loosely and not press it down so that sufficient air can still reach the soil.
• The correct layer thickness varies depending on the material: Dry, coarse material like wood chips can be applied several centimeters thick, while fresh grass clippings should only be spread in thin layers, otherwise they will rot quickly. In this case, it is better to add more layers more frequently.
• It is also important to leave a small gap around the trunk. This allows the bark to dry properly and prevents damage from constant moisture.
• During the growing season, the mulch layer should be checked regularly. Over time, the material decomposes and is worked into the soil. You can add new material as needed or partially remove old, heavily decomposed remnants.
• For heavy or poorly draining soils, it's advisable to mulch more carefully and apply thinner layers. This prevents waterlogging and ensures that the soil remains adequately aerated.

How thick should the mulch layer be?

The correct layer thickness is crucial for its effectiveness. Too little mulch offers little benefit, while too much can smother the soil.

The following values ​​serve as a guideline:

• Wood chips or bark mulch: approximately 5 to 10 cm
• Foliage: approximately 5 to 10 cm
• Compost: about 2 to 5 cm
• Fresh grass cuttings: maximum 2 to 3 cm per layer

It is important that the mulch is applied loosely and not compacted. Especially with fine material like grass clippings, it is better to apply thin layers more frequently than to apply too much at once.

How large should the mulch area be?

Not only the thickness of the mulch layer is crucial, but also its extent. Ideally, the entire area around the tree should be mulched. Even better is to extend the mulch up to the crown of the tree, as this is where a large proportion of the fine roots are located, through which water and nutrients are absorbed.

Small mulch rings placed directly around the trunk offer some protection, but their effect is limited. The larger the mulched area, the better the soil can retain moisture and the more stable the entire system becomes.

In practice, this means: It is better to mulch a larger area somewhat thinly than a small area very thickly.

Maintain a safe distance from the trunk

A common mistake when mulching is placing the material directly against the trunk. This keeps the bark constantly damp, which can promote rot and fungal growth.

Therefore, a small gap should always be maintained around the trunk. About 5 to 10 cm is usually sufficient. This allows the bark to dry better and protects the tree.

How often should you mulch trees?

In most cases, mulching once or twice a year is sufficient. The crucial factor is not so much a fixed schedule, but rather the condition of the mulch layer.

Organic material decomposes over time and slowly disappears into the soil. Therefore, it is advisable to regularly check the area around the tree and add new material as needed.

This may be necessary more frequently with rapidly decomposing materials such as grass clippings. Long-lasting materials such as wood chips, on the other hand, need to be replaced less often.

Should I renew the mulch or leave it?

Mulch does not need to be completely removed when it decomposes. On the contrary, decomposition is an important part of its function, as it introduces organic matter into the soil.

Coarse materials like wood chips can remain for extended periods and are only replenished as needed. Finer materials like grass clippings or leaves decompose more quickly and should be added regularly.

In practice, it has proven effective to check the existing mulch layer and supplement it if necessary, rather than replacing it completely.

Mulching for young and older trees

Not every tree reacts the same way to mulch. Young trees in particular benefit greatly from it, while the effect is somewhat different for older trees.

Young trees don't yet have a deep root system and are more dependent on the upper soil layers. A layer of mulch is particularly helpful here, as it helps retain moisture in the soil and balance temperature fluctuations. Especially in the first few years after planting, mulching can be crucial for the tree's healthy development.

For older trees, the focus is less on water supply and more on the long-term improvement of the soil. Mulch primarily supports soil life and helps to maintain soil structure.

Mulching of trees throughout the year

• Spring: Leave the tree ring uncovered at first so that the soil warms up more quickly. If there is still mulch from last year, you can remove it.
• Summer: A good time to apply a new layer of mulch is after flowering, usually between May and June. This layer is changed periodically throughout the summer to prevent rot.
• Autumn: It is a good idea to remove the mulch after harvesting the fruit to prevent voles from finding shelter. Voles feed on roots, among other things, and could therefore cause some damage to your tree.
• Winter: Leave the tree ring of older trees free. For young trees, you can leave a thin layer of mulch made of leaves. The mulch layer is particularly helpful for young trees that are sensitive to cold.

Mulching or fertilizing – what's the difference?

Mulching and Fertilize They are often confused with each other, but they fulfill different tasks.

• Mulch works slowly and indirectly. It provides organic material that decomposes gradually. This releases nutrients and promotes soil life. At the same time, it improves the soil structure.
• Fertilizer, on the other hand, delivers nutrients in a targeted and concentrated form. The effect usually sets in faster, but is less long-lasting.
• The most effective approach is a combination of both: While mulch creates the foundation and stabilizes the system, fertilizer provides targeted nutrient supply as needed. An ideal complement to mulch is, for example... Worm compost.

Combine mulching and irrigation

Mulching works best in combination with proper irrigation. While the mulch layer helps retain water in the soil, it's crucial that the water actually reaches the root zone. Slow and even watering helps the soil absorb the water instead of it running off the surface. For this, we recommend drip irrigation, for example with... Tree watering bags.

This creates an effective interplay: The water penetrates deep into the soil, and the mulch layer ensures that it is stored there for longer. As a result, the tree is supplied more evenly and can better withstand dry periods.

Avoid typical mistakes when mulching

When mulching, some typical mistakes can significantly reduce the effectiveness or even be harmful:

• Applying mulch directly to the trunk promotes rot and fungal growth.
• Applying mulch too thickly leads to oxygen deficiency in the soil.
• Applying fresh grass clippings in thick layers: risk of rot.
• Applying mulch to compacted soil: water cannot penetrate.
• Mulching area too small: Limited effect

If these points are taken into account, mulching can fully realize its advantages.

Conclusion: Mulching as part of a system

Mulching is one of the simplest measures with a big impact. When used correctly, it protects the soil, improves water retention, and strengthens soil life.

However, mulching unfolds its full potential in combination with Irrigation and nutrient supplyThis creates a stable system that keeps trees healthy in the long term.