What is a Mulch and How to Apply It
In general, mulch is just a material, applied in layers on the soil surface. There are many reasons for mulching. They include conserving soil moisture, improving the health and fertility of the soil, reducing weeds, enhancing visual looks, etc.
This article focuses on mulch, its types, application details, and uses.
Generally, weeds require sunlight to thrive. The mulches block the sunlight and effectively prevent weed growth. Applying multiple layers of mulch increases efficiency. You can also use mixed mulching methods to combat weed growth.
Types of Mulches
There are two types of most widely used mulches – organic and inorganic. Both of them can be applied temporarily (bark chips, wooden chips, etc.) or permanently (plastic sheeting, landscape fabrics, etc.). Both of them can also be applied around the plants or on bare soils.
As the organic mulches decompose, they enrich the soil and improve its quality. However, the woodier or dryer mulches decompose slowly. They also provide lesser nutrients compared to softer mulches.
Naturally, the invertebrate activities incorporate organic mulches (like compost or manure) into the soil. In fact, both commercial producers and gardeners make use of this natural activity to improve the soil quality.
On the other hand, most inorganic mulches do not break. Instead, they have other advantages.
For example, the black plastics (inorganic mulch) generate heat in the soil during the day and radiate the same at night. This helps to keep the heat-loving vegetables (like cherry tomatoes and eggplants) cozy and healthy.
Photo by Dvortygirl (Wikimedia Commons) (CC BY-SA 3.0)
There are many types of organic mulches used in the gardens. We have briefed some of them below.
Bark mulch is best for garden beds, trees, shrubs, etc. where you won’t perform frequent gardening tasks. Naturally, these mulches last longer compared to other finer organic mulches. However, these elements do not mix well with the soils. They also have fewer nutrients comparatively.
You can use grass clippings both as mulch and compost. They suppress weeds well. Having high water content, these clippings dry rapidly. Sometimes, they form a mat preventing water flow. Due to the moisture content, the clippings may also have an unpleasant smell.
After clipping the grass, gardeners usually leave it on the lawn surfaces. As the grass decomposes, it enriches the soil readily.
Naturally, shredded Leaves are one of the perfect mulches. They encourage more invertebrate activities. They also decompose and blend with soil quickly. Mostly, they are available for free. But some commercial houses do sell them.
Straw and Hay
In vegetable gardens, the growers mostly prefer to use straw and hay mulches. Usually, these mulches decompose at a slower phase, lasting the entire growing season. Also, beneficial insects love to nest homes in straw and hay. This helps controlling pests to a large extent. Finally, straw and hay are easy to work into the soil or rake up for new plants.
Nowadays, most newspapers use organic dyes. Hence, you can use them without concerns about chemicals for mulching. Newspaper layers have good moisture retention properties. They can also control soil temperatures and suppress weeds. Some gardeners use newspapers to smother existing grass and start new plantations.
There are many types of inorganic mulches used in gardens. We have briefed some of them below.
Plastic and Landscape Fabric
Plastic and landscape fabrics suit well in spaces like garden beds where you perform less frequent gardening activities. Hence, they fit well for trees, shrubs, and foundation plantings. Normally, these plants do not demand frequent fertilization. So, you may not require to weed them frequently.
Normally, the plastic fabrics block the sunlight, killing weeds. In summer, they also generate immense heat, drying the soil. As a result, many soil microbes, including plant roots die of starvation.
Hence, make sure the plants are getting enough moisture to thrive. If needed, cut holes through the plastic where you intend the water to flow through.
However, most Landscape fabrics are porous and do not stop the water flow unless blocked.
Gravel and Stone
To enhance the drainage, you can mulch the spaces with gravel and stone. You can also use them to generate additional heat in places like rain gardens and Mediterranean herb gardens. These mulches also enhance the ornamental looks of the garden spaces.
On the flip side, it is difficult to remove these mulches once placed. Hence, use them as needed.
Every year, commercial markets introduce various new mulches. Depending on the requirement, choose a mulch that suits your garden spaces well. If needed, consult an expert for advice.
When to Apply
Generally, the application time depends on your goals. Mulches act as insulating barriers between the soil surface and the surrounding air, thereby moderating the soil temperatures. This simply means, mulched soil will be cooler in summers and warmer in winters compared to open soils.
Similarly, mulched soils warm up slowly in spring and cool down slowly in autumn compared to open soils.
In northern climates, winter mulching is useful for plants like strawberry fruits. Apply the pine boughs, hay, straw, etc. in the late fall after the grounds freeze but before the arrival of the coldest days. This helps to prevent rodents to a large extent.
In winters, the repeated fluctuating climates like freezing nights and thawing days heave out the shallow or small rooted plants. Winter mulching helps to reduce the fluctuations in soil temperatures to a great extent. This helps to preserve plants in winter, especially the shallow-rooted ones.
For flowers or vegetables, apply mulch when the soil warms up in the spring. You can also apply additional mulching layers once the soil warms up completely.
The wet, cold soils slow down the rate of germination. They also increase the decaying activities in seedlings and seeds.
How to Apply
Before mulching, remove the weeds from the soil completely using weeding machines. Then apply the mulch layers to the soil. Usually, two layers of mulch are sufficient in shaded spots to prevent weed growth. However, two to three layers may be needed for some fertile lands with abundant sunlight
If your garden space is filled with perennial roots or weed seeds, you can try double-mulching methods. In this method, water the plants thoroughly and spread newspaper layers around them. Then, top them with other commercial mulches.
Some mulches like wooden chips retain moisture. When they are piled against stems of vegetables, flowers, shrubs, etc., they can cause root rot. They can also invite rodents that can destroy the plants or bring various diseases.
Hence, keep these types of mulches at least an inch away from the stems or other contacting parts. In the case of trees, it is advisable to keep them about 6 – 12 inches away from trunks.