What materials can be used for mulching? Which type of mulch to use for which purpose? We show the advantages and disadvantages of bark mulch, pine mulch and co.
Mulch is an integral part of most people’s gardens. Many especially appreciate the visual appeal of different types of mulch. Mulching not only positively affects the aesthetics, however but can also support the plants: It reduces evaporation near the soil, thus preventing plants from drying out, secures the soil from erosion and compensates for temperature fluctuations. In addition, many mulching materials such as bark mulch can be used against weeds: They reduce weed pressure by inhibiting the growth of these uninvited guests. Especially in winter, however, mulch is a real life insurance – it protects plants that can not spend the winter indoors from freezing, ensuring that they come into the next year unscathed. Meanwhile, there is a whole range of materials that are considered suitable for mulching. We tell you here the pros and cons of these materials and which types of mulch should be used for which plant. Find out exactly what benefits mulching brings to the garden in our dedicated article.
Bark mulch is probably one of the best-known types of mulch and especially popular for its attractive appearance. The organic material consists of the bark of various coniferous and deciduous trees and is excellent for mulching perennial beds but is also used for path surfacing. Ferns, hydrangeas (Hydrangea) and rhododendron (Rhododendron) in particular love bark mulch. This suppresses weeds particularly reliably and also shields the soil well from drying out and erosion. At the same time, bark mulch has a soil-activating effect, as it slowly rots to form humus, while additionally providing shelter for various beneficial insects. Unfortunately, bark mulch also comes with numerous disadvantages: fresh bark mulch often contains herbicidal tannins that remove nitrogen from the soil. This problem can be reduced by using bark humus that has already fermented instead of bark mulch and also making sure that there is sufficient nitrogen fertilisation. In addition, purchased bark mulch in particular is often contaminated with elevated concentrations of cadmium. Moreover, not only beneficial insects but also voracious slugs feel particularly at home in bark mulch – so to mulch the vegetable patch, it is better to use other types of mulch.
Pine mulch and pine bark
Pine bark or pine mulch and bark mulch are very similar – with the small but subtle difference that only pine (Pinus pinea) is used as the starting material for the former. As a result, pine bark mulch has many of the advantages of bark mulch. For example, it offers good weed suppression and protection against drying out. Also visually, pine mulch with its attractive reddish-brown colour and beautiful smell is in no way inferior to bark mulch.
In addition, pine bark rots much more slowly, so it does not need to be replaced as often, mosses less and is less likely to be contaminated with pollutants. However, pine mulch also removes nitrogen from the soil during the rotting process (although less than bark mulch), which must be balanced with additional fertilisation.
In addition, pine mulch is often significantly more expensive than normal bark mulch and has a poorer CO2 balance due to the usually long transport route. Pine bark is particularly suitable for mulching perennial beds but can also be used for potted plants. For mulching the vegetable patch, on the contrary, unfortunately, it is not well suited.
Whether by pruning or even cutting down whole trees – wood is produced in almost every large garden. But instead of simply throwing away the clippings, you can put them to good use: Shredded with a shredder, it makes a great mulch material. The advantages here are clear because wood chips are cheap, readily available and (at least if they come from your own garden) also sustainable. At the same time, wood chips rot much more slowly than bark mulch, so you need to renew the mulch layer less often. In addition, wood chips as mulch reliably suppress weeds and prevent both silting and drying of the soil. Unfortunately, however, the wood chips remove nitrogen from the soil, so they are less suitable for mulching the vegetable patch. On the other hand, wood chips are suitable for mulching perennial beds if care is taken to compensate for nitrogen removal by the wood chips through fertilisation. However, wood chips are especially popular in gardens with children – applied in a lush layer, they serve as a shock-absorbing surface on playgrounds or walkways that can minimize injuries.
Leaves for mulching
For many gardeners, the fallen leaves in autumn because only annoying work, while autumn leaves in the garden can also be used wisely. In fact, you can turn adversity into a virtue through skilful action. Indeed, leaves can be wonderfully used as mulch that does not cost a single penny. Thus, a layer of foliage protects the soil from drying out and also acts as a weed guard. Over the winter, the foliage is then slowly decomposed by microorganisms, releasing nutrients into the soil. The protective effect of foliage against frost is particularly good, however, and is especially important in autumn and winter – leaves are thus ideal for mulching the perennial bed, as they reliably protect plants that are sensitive to cold. Foliage can also be used to mulch the vegetable bed, as woodland plants such as raspberry (Rubus idaeus) or strawberry (Fragaria) in particular respond positively to leaf protection in the root zone. Only the appearance of the foliage in the bed may bother some garden owners, and therefore represents a disadvantage. Also, only healthy leaves should be used for mulching, otherwise diseases such as mildew can spread in the garden.
Lastly, pay close attention to the type of foliage chosen – some foliage, such as from the walnut tree (Juglans regia), contains tannins that can limit the growth of other plants.
Needles for mulching
A coniferous tree in the garden can be an asset – if only it was not for that annoying needle litter that accumulates year after year. But, as with foliage, the needles of almost all coniferous trees also make an excellent mulch material. On the one hand, they prevent strong temperature fluctuations on the ground and reduce soil compaction, and on the other hand but at the same time – like many other types of mulch – they allow better water infiltration. At the same time the needles take a very long time to rot, which means they need to be replaced less frequently. The terpenes contained in the needles delay the germination of other plants, so that weeds are effectively suppressed. Needles should not be used as a mulch around seedlings or young plants, however, as this effect can also have a negative impact on them. Established plants, on the other hand, are not negatively affected. Furthermore, it should be noted that needles have a low pH, which means that needle litter is especially good for mulching bog beds or heather plants, and rhododendron and hydrangeas love it.
Contrary to popular belief, however, the needles of trees are also suitable for mulching vegetable beds: In fact, the ideal pH for most vegetable plants is in the slightly acidic range, so mulching with fir or pine needles is not a problem if the soil has not previously had a pH that is too low. Blueberries (Vaccinium myrtillus) and cranberries (Vaccinium vitis-idaea) even prefer acidic soils, so a mulch layer of needles is excellent here.
Straw for mulching
Mulching with straw has become a tradition in many gardens – no wonder, after all, straw is not only cheap and readily available but also offers numerous advantages as a mulching material. Thus, straw allows good aeration of the soil, suppresses weeds and releases nutrients into the soil when weathered. Straw is especially popular for vegetable bed mulching because plants such as strawberries and courgettes (Cucurbita pepo var. giromontiina) do not lie directly on the ground and thus remain nice and clean. Straw is particularly useful for mulching plants with a long growing season – such as tomatoes (Solanum lycopersicum) or pumpkins (Cucurbita) – because it rots very slowly. Perennial shrubs also benefit, which is why straw is just as suitable for mulching perennial beds.
However, straw also removes nitrogen from the soil, so care must be taken to ensure an adequate nutrient supply to the soil. In addition, care should be taken in the kitchen garden to use only untreated straw for mulching, as treated straw may contain residues from the chemicals used.
Lawn clippings for mulching
Whether you have a small garden or large estate – lawn cuttings accumulate in almost every garden. Anyone who has had enough of simply throwing away the mown greenery can, however, still help the lawn cuttings to have a second life: As a mulch, it prevents desiccation and siltation, promotes soil life and inhibits the growth of weeds. The particular advantage of grass cuttings lies in their rapid availability and slow rotting. Nevertheless, when mulching with lawn clippings, attention must be paid to a few points. You should always only spread a thin layer of mulch and be careful that it does not become too moist, otherwise it can quickly rot. If you mix some straw with the lawn clippings, you can minimise this risk by improving the ventilation of the mulch layer. Also, lawn clippings remove nitrogen from the soil during decomposition, so an adequate supply of nutrients is essential. Grass clippins are especially suitable to mulch the vegetable bed -. between young vegetable plants, over time this forms a stable mulch cover, which keeps moisture in the soil.
Expert tip: Cut grass is also ideally suited for lawn mulching: So-called mulching mowers shred the grass clippings directly while mowing and then leave them as fine mulch on the lawn, where they rot and return their nutrients to the soil.