Lava mulch has revolutionized the garden. What Mother Earth brings to light as bubbling magma, clever hobby gardeners know how to use it as a problem solver for bed and plant care. This guide highlights the special properties and expert use of lava mulch. You can find out here what advantages and disadvantages are associated with the volcanic natural product.
What is lava mulch used for in the garden?
Lava mulch is a light, air-permeable and rot-free garden rock that is used as a soil improver, pavement, weed suppressant and plant care. It comes from cooled and crushed lava and is available in different grain sizes and colors.
- When lava is cooled and crushed, lava mulch is created for the garden.
- Lava mulch is light, air-permeable, non-slip, odorless and does not rot.
- Hobby gardeners use lava mulch as a soil conditioner and paving paths, for weed suppression and plant care.
What is lava mulch?
Lava mulch is cooled, solidified lava. The pure natural material is created when liquid magma bubbles up from the earth's mantle. This sometimes happens spectacularly as a volcanic eruption. On the earth's surface, the volcanic extraction product cools quickly and turns into a covering layer that is broken down and crushed into lava mulch. The result is a valuable natural product with these beneficial properties for the garden:
- light and breathable
- does not rot
- odorless
- steady
- suppresses weeds
- prevents soil compaction
- prevents waterlogging
- protects against cooling in winter and drought stress in summer
Weighing about one ton per cubic meter, lava mulch is a real lightweight among the garden supplies. Breathable and inorganic are exactly the properties that nature-loving gardeners want from an environmentally friendly problem solver in the bed. Find out where lava mulch is useful in the garden in the following section.
Versatile application
Lava mulch is available in different grain sizes
Grain sizes from 8 to 32 mm offer hobby gardeners a wide range of possible uses for lava mulch in their green realm. The best ideas for competent and beneficial use are summarized in the following table:
| Garden | Plant Care | Pond |
|---|---|---|
| Road paving | Substrate loosening | Soil |
| Weed suppression | Drainage | Bank fortifications |
| erosion blocker | Heat storage | Plant basket bottom layer |
| Design element | Evaporation protection | |
| Snail defense | Plant base |
Grain sizes from 2 to 8 mm are referred to as lava granules. With this grain size, lava is an excellent alternative to road s alt in winter. If unpaved work paths in the garden become slippery when it rains, lava granules are available as anti-slip grit. Aquarists swear by lava granules as a filter medium and substrate.
Excursus
Lava mulch vs bark mulch
In a direct comparison with classic bark mulch, lava mulch is clearly ahead. Lava mulch does not rot, does not smell and does not remove any valuable nutrients from the garden soil. The reason for the positive properties are inorganic, mineral components. In contrast, bark mulch is made from tree bark and is therefore one of the organic materials for the garden. This is associated with a limited shelf life. At the beginning of decomposition, bark mulch removes important nutrients from the bed, which can cause deficiency symptoms in young plants. The organic mulching material only fulfills its role as a natural fertilizer later. A musty smell is a negative. Furthermore, bark mulch offers ideal conditions for voracious snails, whereas lava mulch is useful as a migration barrier.
Application in the garden – tips & tricks
Lava mulch has many uses in the garden
Lava mulch does not dissolve within a few years like organic mulches. For this reason, crushed lava serves as an ideal top layer in the bed and as a planting base for ornamental and vegetable plants. The volcanic natural product keeps weeds under control, ensures permeable soil and prevents waterlogging. When used correctly as mulch, lava keeps the soil moist and warm for longer. Grain sizes from 16 mm store the sun's rays during the day and give off heat to your plants at night. Strong thunderstorms do not wash away bed soil if lava mulch is available. To ensure that lava fulfills its tasks perfectly as mulch, planting base and paving paths, important details are important:
Lava as mulch
The hobby gardener spends a large part of his time in the bed fighting weeds. With lava mulch, the amount of work is reduced to a tolerable level. Dandelions, groundweed, couch grass and the like have bad cards if you use lava as mulch like this:
- Pulling existing weeds
- Spread lava mulch on the ground
- Ideal layer height: 6-8 cm
Grain sizes of 8 mm, 16 mm up to a maximum of 32 mm are well suited for long-term weed suppression. Lava mulch against weeds is only not recommended under deciduous trees because autumn leaves cannot be removed from them or can be removed with considerable effort.
Lava as a plant base
Lava secretes valuable nutrients
With a grain size of 4 to 8 mm, maximum 16 mm, Lava is at the feet of flowers, perennials and vegetables as an innovative planting base. Although the volcanic rock does not decompose, it releases small amounts of magnesium over time as a desirable contribution to lush green, he althy leaves. To ensure that the natural mineral product makes optimal use of its advantages, the following step-by-step procedure has proven to be excellent in practice:
- Best time is in autumn
- Weed the planting area, dig deep, remove old roots, stones, coarse lumps of earth
- Place perennials, grasses, succulents in the soil and water
- Apply lava mulch about 4 cm high on the free bed area and the root discs
- Important: Do not cover plants with lava mulch
- In December, add another 2-3 cm of mulch
It is advisable to proceed in this order. If you first spread lava mulch in the bed and then plant the plants, the lava grains will be in your way. It is time-consuming to push the top layer away a little for each individual young plant in order to plant the perennial properly.
Lava mulch for paving paths
In natural gardens and cottage gardens, paved paths are not to everyone's taste. Traditionally, bark mulch acts as a natural surface for paths. However, the organic material decomposes quickly and must be replenished regularly. This is where lava mulch comes into play as a permanent, sturdy pavement. How to do it right:
- Measure and mark the route
- Dig the soil 10-15 cm deep
- Spread sand as a base layer at a height of 3-5 cm
- Tamp down the layer of sand and slurry it in with water from the watering can
- Apply lava mulch
A border is advantageous so that lava mulch does not spread in all directions when paving the path. A boundary is essential if paths with lava surface border a lawn. If pieces of lava get between the lawn mower's blade bars, significant damage is inevitable. Lawn edges, for example made of popular Corten steel, are well suited and almost invisible. Close to nature, you limit the path with wood as a mini palisade.
Creative design element
Lava mulch with its strong red tone looks pretty
Lava mulch is a visual asset for imaginative garden design. The volcanic natural material is very popular as a cover layer in the prairie garden. Lava harmonizes wonderfully as mulch with ornamental grasses and gives the representative front garden a permanently well-kept appearance. Subtle colors make the natural material the ideal component for creative garden design. As a rule, lava is red-brown to gray when it emerges to the earth's surface. The composition and manufacturing process allow for other colors such as anthracite, black, red and brown.
Babbling water worlds are impressively accentuated with lava mulch. If lava forms a covering layer around the fountain or other water features in the garden, muddy, trampled earth is a thing of the past. A sturdy bank reinforcement made of lava grains makes maintenance work on the pond and stream much easier.
Calculate the amount of lava mulch – this is how it works
Using lava mulch in the garden is also a cost factor. Compared to conventional bark mulch, lava rock costs more. If you determine the exact quantity required with a sharp pencil, you will avoid anger and frustration. The following quick guide explains how to correctly calculate the amount of lava mulch:
- Measure the length and width of the area
- Determine the height of the mulch layer (ideally 6-8 cm)
- Note down the determined values in meters
- Calculation formula: Height x width x of lava mulch in cubic meters
Alternatively, you can call up a requirements calculator on the Internet, enter the measured values into the mask and automatically receive the result.
Tip
Balcony gardeners appreciate lava mulch in many ways. As drainage in the flower box, excess irrigation water can drain away quickly. The substrate stays moist longer and does not crust under a cover of lava. Strawberries in the flower box stay appetizingly clean with lava mulch.
Advantages and disadvantages
Regardless of its useful properties and diverse uses, lava mulch does not only come with advantages. The enthusiastic hymns of praise for the volcanic natural rock should not hide one or two disadvantages. The following table compares the advantages and disadvantages of lava mulch:
| Advantages | Disadvantages |
|---|---|
| durable, rot-proof | does not release nutrients |
| suppresses weeds | not suitable for deciduous trees |
| improves the soil structure | can harm lawn mowers |
| prevents waterlogging/erosion | more expensive than organic mulch |
| well tolerated by plants | |
| odorless | |
| steady | |
| decorative |
In a direct comparison, a higher price has so far been paid for lava mulch than for bark mulch. In this context, it should not be overlooked that lava as mulch must be purchased once, whereas bark mulch must be replenished at regular intervals. In addition, a gradual increase in the price of bark mulch has been observed in the market since the discovery of the material for combustion in wood chip heating systems.
Frequently asked questions
Where can you buy lava mulch?
Increasing demand has brought lava mulch out of the niche of hard-to-find garden products. After lava mulch was primarily available from specialized building materials dealers for a few years, most hardware stores and garden centers have now integrated lava into their standard range. Obi, Hornbach and Hagebau offer inexpensive lava mulch in various grain sizes and colors locally and online. Lagerhaus in Austria also has the natural product in its range. You can also consult internet portals such as Amazon and Ebay to have lava mulch delivered directly to your home.
What is the difference between lava mulch and lava granules?
The grain size makes the difference whether lava is to be bought as mulch or granules. Grain sizes of 2 to 8 mm are usually offered as lava granules. Specialist retailers describe grain sizes from 8 to 32 mm as lava mulch. However, due to the lack of clear DIN classifications, the boundaries are fluid. In particular, grain sizes from 8 to 16 mm are offered under both product names.
How much lava mulch per m² should be distributed in the bed for effective weed control?
Long years of experience in the garden have proven that a 6 to 8 centimeter thick layer of lava mulch reliably suppresses most weeds. When you calculate the amount you need, it depends on the grain size you choose. With a grain size of 16-32 mm, 0.08 cubic meters (=0.09 tons) of lava mulch can be purchased per square meter. Competent providers provide practical calculators for determining the quantity of lava in finer or coarser grain sizes, such as kiesdirekt.de for Germany or kieskaufen.at for Austria.
I've had enough of the red-brown lava mulch. How can I remove the top layer from the bed?
Since lava mulch is a purely natural product, time-consuming disposal work is not necessary. To remove lava as mulch, simply work the grains into the soil. This has the particular advantage that the soil is additionally loosened up and protected against waterlogging. Alternatively, rake up the volcanic mulch with a rake and sift out crumbs of soil. If you need drainage for your potted plants in the future, you already have the perfect, inorganic material at hand.
We would like to buy lava mulch 16/32 for our garden. What price should we expect if we need a ton of lava rock?
Specialist retailers charge an average of 250 to 280 euros for a ton of lava mulch in a big bag. Big bags are delivered using a special lifting platform truck. Therefore, there are additional costs for shipping, which are usually not included in the purchase price. We determined these prices in online trading. Many years of experience have shown that local building materials dealers and hardware stores have seasonal special offers that are not published on the Internet. Our tip for bargain seekers: Call regional lava mulch suppliers before ordering from national sellers and digging too deep into your pockets. With a little luck you can get discounts of up to 50 percent.
Is lava rock suitable as mulch for all plants?
Lava mulch harmonizes with almost all plants that thrive in ornamental and kitchen gardens. Use lava rock as flooring under perennials, flowers, conifers and evergreens for a well-groomed appearance. Even in vegetable beds, lava as mulch reduces annoying weeding to a minimum from a layer height of 6 centimeters. Lava mulch is only not recommended under deciduous shrubs and trees because autumn leaves are difficult to remove.
Tip
Lava mulch is the ideal bulwark against snails. Sharp stones and sharp-edged grains are anathema to the voracious pests. If voracious slugs are after your flowers, perennials and vegetable plants, cover the ground with lava mulch. Grain sizes from 8 mm to 16 mm, ideally combined with coffee grounds, have proven to be excellent in practice.