Mulching - save water and promote growth

Jun 22, 2024

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Benji Freeman

Mulch - Wasser sparen und Wachstum fördern

Content of the article

Meaning and history of mulch
The benefits of mulching
The different materials for mulching
Summary - What should be considered when mulching
The Practice - How Mulch is Distributed

In places where nature is still untouched, plants always cover the ground with fallen leaves and branches. Mulching combines plant care with soil ecology and demonstrates how closely everything in nature is intertwined. The return of organic matter to the soil is a principle that occurs everywhere in nature – from forest floors to meadows. It is a time-honored gardening practice that offers a multitude of benefits and was already practiced in plant cultivation in ancient times by the Incas, Mayans, and Aztecs. Mulch promotes a holistic approach to natural cycles.

Covering beds with mulch is already well-known in the fields of sustainable gardening and permaculture. Because it reduces resources and maintenance work, it's very attractive for both beginners and experienced gardeners. The minimal additional effort required to spread the mulch can produce higher yields, reduce watering time, and promote plant health.

To fully utilize the positive effects of mulch, it's important to understand its underlying principles. Otherwise, things can go wrong unexpectedly. To avoid this, we've presented all the important information here.

Meaning and history of mulch

The history of mulching is characterized by observation, learning, and a return to natural processes. What once arose from experience and was passed down through generations is now scientifically sound and ecologically indispensable. Mulching represents a gardening culture that understands the soil as a living system and protects, nourishes, and preserves it.

Mulching is essentially a method of improving garden soil and promoting plant growth. In agriculture, this is referred to as 'promoting soil tillage,' which describes the ideal state of fertile soil.

What is mulching?

Mulching means covering the soil with a protective layer of organic or inorganic materials. A mulch layer is a layer of rotted or unrotted plant residue up to 15 cm deep that covers the soil, making it permeable to air and light.

This layer can consist of various materials, depending on the purpose and plant species.
Due to ecological reasons, we will refer only to organic materials in this article.

The benefits of mulching

Moisture retention and distribution
Nutrient supply
Temperature regulation
Weed suppression
Promotion of soil life
Protection against erosion, frost, and desiccation
Creates habitats for insects
Protects ground-level fruits from rot
Conserves water and fertilizer
Creates a loose soil structure

As protection against the elements, mulch creates an insulating layer that cools in summer, warms in winter, protects against soil erosion, and provides nutrients to soil organisms. This can extend the growing season of crops. It provides a soft and dry base for fruits that ripen close to the ground, preventing mold growth.

When applied correctly, a mulch layer can reduce water evaporation by up to 80% and creates consistent moisture levels beneath the layer, which many crops require to achieve good yields. A mulch layer also serves to regulate temperature and compensate for significant temperature fluctuations. Mulch also helps protect against heavy rain and reduce soil erosion, which is the washing away of soil.

The opaque layer prevents most wild plants from growing through, significantly suppressing unwanted weeds.
The decomposing mulch layer also contributes to improving fertility because microorganisms and soil organisms, such as earthworms, convert the material, making its nutrients continuously available to plants.

As the mulch layer decomposes, a vibrant microcosm emerges, improving soil structure, stimulating humus formation, and enabling optimal oxygenation.
Insects and other beneficial microorganisms find a home in the partially moist and dry mulch layer and can reproduce there, maintaining biological balance.

The different materials for mulching

Materials used as mulch have different ingredients and therefore different properties. If the mulching material is not used correctly, its effectiveness can be limited or even detrimental. Choosing the right mulch material is crucial; it determines, among other things, the pH value and the carbon/nitrogen ratio (C/N ratio).

Here we provide an overview of the special properties of proven materials and application tips that help you use the different materials:

Straw
Hay
Grass clippings
Fresh wild herbs
Bark mulch
Wood chips
Sheep's wool

Straw

Straw is a proven mulch material in vegetable gardening, particularly appreciated in natural and organic gardens. It consists of the dry stalks of cereal plants such as wheat, barley, or rye and offers numerous benefits for soil and plants, provided it is used correctly.

Special features at a glance

Low in nitrogen: Unlike hay or grass clippings, straw contains few nutrients, which can lead to nitrogen deficiencies in vegetable gardens when it decomposes.
Contains seeds: Straw can contain seeds due to harvesting methods that germinate in the garden.
Longevity: Decomposes slowly and lasts for a long time as a mulch layer.

Usage tips

Material selection: Use only well-dried and, if possible, seed-free straw to avoid unwanted weeds.
Prepare the straw: To prevent seeds from germinating, spread the straw and keep it moist for 5 days. Then let it dry again.
Distribute the straw: Lay the prepared straw in a layer 10 to 15 cm thick, extending close to the plant stems. Due to the air pockets it provides, the layer can be somewhat thicker.

Hay

Hay is an excellent organic mulch for vegetable beds, especially in natural or permaculture gardens. Its nutrients promote plant growth and revitalize soil life. It consists of dried grass and herbs and offers beneficial benefits for both soil and plants.

Special features at a glance

Nutrient content: Contains many minerals and trace elements that are released during decomposition and support plant growth.
Fast-decomposing: Hay decomposes relatively quickly, thus promoting humus formation and soil structure.
Contains seeds: Untreated hay may contain seeds that will germinate in the garden.

Usage tips

Material selection: Use only well-dried, clean hay. Damp hay can already be moldy or rotten, causing further mold growth in the bed.
Preparing the hay: To prevent seeds from germinating, spread the hay out, as with straw, and keep it moist for 5 days. Then let it dry again.
Distribute the hay: Spread the hay evenly over the bed in a layer 5 to 10 cm thick. If there is heavy weed growth, a little more may be needed.

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Grass clippings

Grass clippings are a particularly nutrient-rich and flexible mulch material, making them ideal for use in vegetable gardens. They not only retain soil moisture but also improve nutrient supply. They are regularly generated in many areas when mowing lawns and can be put to good use. Those who mow regularly and use the clippings wisely transform waste into a real garden helper.

Special features at a glance

Nutrient content: Fresh grass clippings contain a lot of nitrogen, which promotes plant growth.
Heat generation: If the layer is too thick, fermentation and unpleasant odors can occur, which greatly increases heat generation.
Rapid decomposition: The particularly fine structure decomposes quickly and effectively improves soil structure.

Usage tips

Allow to dry: Fresh grass clippings should be allowed to dry slightly before spreading to prevent clumping or rotting. This reduces the risk of fermentation and mold growth.
Distribute grass clippings: Spread the grass clippings on the bed in a layer 2 to 3 cm thick. Ensure that the stems or leaves of the plants do not come into contact with the mulch, as this prevents rot and fungal growth.
Regularly check: The mulch layer should be checked regularly and loosened or replaced as needed to ensure good aeration.

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Fresh wild herbs

Mulching with fresh wild herbs is a simple, cost-effective, and environmentally friendly way to cover garden soil.
Due to their high water content, wild herbs are flexible and therefore ideal for placing between plants as mulch. They reliably cover the soil and are breathable, while also providing valuable nutrients that are readily accepted by all living creatures.

Special features at a glance

Nutrient content: Many wild herbs such as nettle, ground elder, and dandelion contain valuable minerals and nitrogen that are released into the soil as they decompose.
Availability: They are readily available in many locations, making them a sustainable resource.
Rapid decomposition: Wild herbs decompose rapidly, effectively improving soil structure.

Usage tips

Do not use flowering herbs: Only use wild plants without seed heads to prevent seeds from being accidentally spread throughout the bed.
Chop up plant parts: Roughly chopping plant parts accelerates decomposition and prevents clumping.
Distribute wild herbs in the bed: Spread chopped, fresh plant parts around the plants in the bed in a thickness of 10 cm. Note that layers that are too thick can lead to rot or mold.
Add more mulch regularly: Wild herbs decompose quickly, so the mulch layer should be renewed regularly.

Bark mulch

Bark mulch is a natural mulch made from shredded tree bark, usually from conifers such as spruce or pine. This mulch has larger wood pieces, is easy to spread, and provides a long-lasting and reliable cover for the soil. Although it is primarily used in ornamental gardens, bark mulch can also be used effectively in vegetable gardens under certain conditions.

Special features at a glance

Nitrogen depletion: Fresh bark mulch removes nitrogen from the soil as it decomposes. This can lead to growth problems for nutrient-demanding plants.
pH regulating: The acidic material can acidify the soil environment and subsequently affect soil life.
Longevity: Bark mulch decomposes slowly, thus providing long-term protection.

Usage tips

Suitable plants: Use only in perennial vegetable beds or in combination with hardy vegetables such as pumpkin, zucchini, or rhubarb.
Distributing the bark mulch: Spread the material 5 to 7 cm thick. Keep a distance from plant stems to prevent rot.

Wood chips

Wood chips are created by mechanically shredding wood, usually using a chipper. This typically involves bark, branches, tree and shrub cuttings from untreated wood. The shredded wood pieces can be easily distributed. These are primarily used to improve the accessibility of garden paths, but they can also be used as mulch around trees or even in herb beds.

Special features at a glance

Nitrogen depletion: As they decompose, fresh wood chips bind a lot of nitrogen from the soil, which can lead to nutrient deficiencies in plants.
PH regulation: The mostly acidic material, made from mixed wood species, can slightly acidify the soil environment and subsequently affect soil life.
Longevity: Wood chips decompose slowly, making them ideal for permanent areas such as paths or around trees.

Usage tips

Use after decomposition: Fresh wood chips remove a lot of nitrogen from the soil as they decompose. Therefore, it's advisable not to use them fresh in the vegetable patch, but to store them for 6 to 12 months.
Suitable plants: Ideal for woody plants, shrubs, fruit trees, and paths. Less suitable for heat-loving herbs or sensitive perennials.
Spreading the wood chips: Spread the chips in a layer about 5–10 cm thick. Apply more for paths, but less for sensitive plants.

Sheep's wool

Sheep's wool is not only a long-term fertilizer but also an excellent mulch material. Due to its structure and beneficial properties, this natural material provides ideal nutrients for vegetables, fruit, and ornamental plants.

Special features at a glance

Nährstoffgehalt: Wolle ist ein Naturprodukt und zersetzt sich mit der Zeit im Boden. Dabei gibt sie Nährstoffe wie Stickstoff, Kalium, Phosphor, Schwefel und Magnesium an an den Boden ab, was das Pflanzenwachstum stark verbessert.
Feuchtigkeitsspeicherung: Durch die Faserstruktur mit Hohlräumen kann Wolle Wasser speichern und langsam wieder abgeben. Das hilft den Boden auch bei Trockenperioden gleichmäßig feucht zu halten.
Durchlässigkeit: Durch die Beschaffenheit der Wolle, sickert Regen oder Gießwasser langsam hindurch und erreicht so zuverlässig den Erdboden. Die lockere Struktur der Schafwolle ermöglicht eine gute Belüftung des Bodens, was wichtig für Mikroorganismen und Wurzelatmung ist.
Schädlingsabwehr: Durch den Geruch und die Textur der Wolle, meiden in der Regel Schnecken, Wühlmäuse und Maulwürfe die nähe und halten sich dadurch aus dem Garten fern.

Usage tips

Use raw wool: Unwashed wool with lanolin (wool grease) is particularly nutrient-rich. It can be used directly without prior cleaning.
Preparing the wool: Roughly pull the wool apart so it lies loosely, ensuring air circulation and water permeability.
Distributing the wool: Spread the pulled wool evenly between the plants and then cover with a little soil. When laying it out, ensure that the wool is 2-3 cm away from the stems. For a normal mulching effect, a 3-5 cm thick layer of wool is sufficient. For strong weed control, 5-8 cm is sufficient.

Summary - What should be considered when mulching

After fertilizing with unfavorable material (C/N ratio)
pH value for sensitive plants
Permanent moisture promotes mold growth and snail infestation
Soil cultivation is no longer possible afterwards

Prolonged moisture not only increases mold growth but also attracts more slugs over time. Each type of mulch also influences the soil's nutrient content and pH level. Consider the nutrient requirements and whether the plants require a specific pH level. You can find the correct value for each plant in the product descriptions for each variety on our website.

Many organic materials can be used for mulching and serve their purpose. Prioritize using garden waste that suits the characteristics of your bed.

The timing of mulching depends on environmental conditions. In subtropical climates, ideally, beds are always mulched immediately after preparing the soil to prevent drying out and promote soil life. For seeding or planting, the mulch is pushed aside in specific areas and then re-covered. In temperate climates, mulching depends on weather conditions. Mulching is not advisable in persistently high humidity, but highly recommended during heat and frost.

The practice – How mulch is distributed

To ensure that mulch, such as straw or hay, remains stable on the beds even in windy conditions and demonstrates its benefits, a certain simple technique is recommended. The basic idea is that the mulch forms a closed, breathable carpet. To achieve this, the individual pieces are pushed together after the mulch has been placed. The individual mulch pieces then form a large, stable covering of the soil, which remains securely in place even in severe weather. Additionally, the applied layer of mulch can be moistened with water so that the loose material settles under its weight and takes on the shape of the bed.

The thickness of the mulch layer depends on the materials used and is chosen according to weather conditions. A thicker layer decomposes more slowly and retains more moisture, while a thinner layer can dry out and decomposes more quickly. The right type of material makes all the difference.