Raised beds have gained much popularity over the past few years. While making one, a common question arises: What should be put at the bottom of the raised beds?
Common materials to put at the bottom of raised beds are newspaper, cardboard, grass clippings, leaves, mesh wire, landscape or hardware fabrics, stones, and other organic matters. These materials create a barrier between the soil and the ground, which improves drainage and reduces weed growth.
There are countless materials, both affordable and costly. This article will share various materials to put at the bottom of raised beds.
Benefits of putting materials under the raised beds
Creating raised beds requires a lot of effort and investment.
Since you put effort sincerely, you would like to make it work at all costs.
Creating barriers in the raised bed between soil and ground has a lot of benefits that are worth the expense, time, and effort you put in.
Let’s look at the advantages:
Prevents weed growth
Creating barriers between the raised bed’s soil and the garden’s ground prevents weed growth and extra grass growth in that area.
Cardboards and newspapers are effective materials to control this weed growth.
But, other materials and organic mulches will also help.
A thick layer of mulch at the bottom of the raised bed will stop the weeds and other grasses from growing.
Raised beds dry faster than the ground soil.
It prevents water accumulation and saves your plants or vegetables from overwatering.
Lining at the bottom of the bed encourages water retention, which ultimately gets drained.
Heavy soils under the raised beds can prevent the soil from draining properly.
Putting a good layer of lining will prevent this water accumulation.
Improves soil quality
Many add mulches at the bottom of raised beds to create barriers or linings.
These materials can add essential nutrients to the soil once they get decomposed.
It further supports healthy plant growth.
Some regions have rodent problems.
Rodents can create chaos and feast in the garden by feeding on the plants.
Materials like rocks, stones, and hardware fabrics help prevent these pests.
Prevents soil contamination
Garbages, construction sites, pesticides, and other chemical products can contaminate the ground soil and make it unfit for plants and vegetables.
If your ground is one such and you have raised beds, use materials to create a thick layer between the raised bed’s soil and the ground’s soil.
It will prevent the ground soil toxins from reaching the soil in the raised beds.
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17 Materials to put in the bottom of the raised beds
Though there is no need to use these materials at the bottom, they can improve your plant growth and vegetable harvest to a great extent.
You will receive much better results with barriers than those growing in the ground or raised beds without barriers.
Here are the best materials for putting in the bottom of raised beds:
Leaves are also a good option for creating barriers.
But it also decomposes faster, within 6-12 months.
Gathering leaves is an easy option, especially if you are a professional gardener.
Even if you are not, collect them from nearby nurseries.
Once decomposed, these composted leaves will add lots of organic matter to the soil, thus making it more nutritious and healthy for your plants and veggies.
Add lots of leaves if you wish to slow down the decomposition process.
When the leaves get clumped together, the decomposition process reduces.
The more leaves you add, the slower the decomposition gets.
One of the cheapest materials to put in the bottom of the raised bed is newspaper.
It is easily available as all houses receive them daily.
Spread some newspapers at the bottom of your raised bed.
Then fill the bed with the right kind of soil as per your plant’s requirement and then plant your plant.
Even if you don’t have newspapers at home, collect old newspapers from neighbors, shops, hotels, grocery stores, libraries, and recycling centers.
Though newspapers are resistant to decomposition, they will ultimately break down and get mixed with the ground soil.
Sadly, your barrier will break down, but your soil will receive lots of carbon which is a very good point.
Carbon helps feed nutrients to the soil’s microbes, leading to healthy garden soil.
If you want the newspapers to decompose slowly, add multiple newspapers to create a thick barrier.
One concern is the ink used in the paper for writing.
The link may add toxins and chemicals to the soil and make it unhealthy.
But here is the plus point.
The ink used is soy-based.
So it will cause less harm to the soil or your plant/vegetables.
The next abundant and cheap material is cardboard.
Many household materials arrive in cardboard packages.
Use them for good reasons instead of just throwing them away.
Put some cardboard at the bottom and then the soil for planting.
Cardboards, too, will decompose someday.
But it will take longer than the newspaper because they are relatively thick and hard.
Usually, cardboards take 4-6 months to decompose.
It depends on the cardboard you use, especially thickness and quality.
If you don’t have any at home, buy them from stores or collect them from your neighbors and recycle centers.
Avoid using glossy print cardboards like soda boxes, shoe boxes, or cereal boxes.
Cardboards having glossy inks release harmful toxins into the soil during decomposition.
It further harms the plants or veggies you grow in your raised beds.
4. Grass Clippings
Grass clippings work like leaves.
Once decomposed, it will add humus to the soil and choke the weeds and extra ground grasses.
Apply a 2-4 inches thick barrier layer at the bottom of the bed.
Check that the grass doesn’t go to seed before the cutting.
Otherwise, your raised beds will have lots of grass with other plants.
Mechanically clipped grasses release an oily-gassy smell.
So, avoid these grasses as these add harmful toxins to the soil and make it unhealthy for the plants.
5. Woods, woodchips, or other wood materials
For a solid barrier, use woody materials like wood chips.
It will create a stronger barrier and choke the weeds and grasses much better than the previous options.
Avoid using pressured lumber or glued woods like plywood or OSB.
The glued woods can release harmful toxins into the soil, making it unhealthy for the plants.
Decomposing lumber is a great choice as it adds beneficial soil-borne bacteria to the soil and makes it healthy for plants and veggies.
You can also add wood chips with cardboard or newspapers.
First, put the cardboard or newspaper and add a few inches of wood chips.
It will slow down the decomposition process and create a very thick layer.
However, one disadvantage here is that excessive wood chips add a lot of nitrogen to the soil, making it more acidic.
So, you must add limited wood chips and monitor the soil.
Other woody materials include twigs, branches, and logs.
Though they might not suppress weed growth, they can improve the soil quality after decomposition.
Straw is an excellent choice for creating barriers in the raised beds at the bottom.
Straws are affordable and easy to collect.
They help suppress weed growth and add sufficient organic matter to the soil, thus making it healthy for the plants.
Apply straw over the newspaper or cardboard.
However, you can also apply them without any cardboard or paper.
Straws suppress the wood growth and add carbon-rich matter to the soil after decomposition.
The humus formed after the decomposition will keep the soil nutritious for a long time.
Add 4-6 inches of straw at the bottom of the raised bed.
Remember that straws can shrink once the decomposition starts.
So, add a thick layer to slow the decay process and increase the timing of the barrier.
Check the straws very well and then apply them.
Many materials come infested with bugs, pathogens, or weed seeds.
If you are unsure about how to differentiate, collect organic straw.
These materials will be free from weed seeds, pests, pathogens, and other chemical products.
7. Stones and rocks
Another cheap and easily available product is stones or rocks.
Rocks are known to improve drainage to a great extent.
But, if used in the wrong way, they can be the cause of prolonged saturated soil.
If the ground soil of your garden is clayey, adding a layer of stones at the bottom of the raised bed will improve the drainage and save your plants from overwatering.
The water will go through the raised bed soil and settle over the stones if it doesn’t get filtered by the ground soil.
So there won’t be any waterlogging.
A thick layer of rocks can trap the water over the rocks.
As a result, the water will not drain, and the soil of your raised bed will remain waterlogged.
So, use stones or rocks wisely.
8. Pine needles
These are generally used as mulches, but you can also use them at the bottom of your raised beds.
These materials can retain moisture for a long time and thus benefit moisture-loving plants.
Besides, pine needles decompose very slowly, and once they start decomposing, they make the soil very healthy for the plants.
Pine needles stop the weeds from entering your raised bed soil.
They kill the weeds naturally and don’t have any weed-killing chemicals.
So, your plants and the soil are safe.
9. Rubber mulch
This material is a great alternative for landscape fabric or stones.
But, it is expensive.
Despite being expensive, rubber mulch is worthy because they prevent weeds and retain moisture during droughts.
Rubber mulches are made from recycled tires.
So, when they break down over time, the soil gets the benefits of rubber.
10. Coconut fiber
Coconut fiber has a lot of benefits.
Adding some at the bottom of the raised beds will control the soil temperature.
Coconut fiber won’t break down.
Therefore, you don’t have to replace it from time to time like other materials.
As a regulator, it can retain heat in the soil, which is advantageous for winter.
You can use this as an alternative to gravel or stones.
Coconut fiber is easily available and very cost-effective.
It can also be used as mulch to retain the moisture level, so you don’t have to water the plant repeatedly.
This option is rare, but people use wool at the bottom of the raised bed.
Add a thick 6-inch layer of barrier with sheep wool at the bottom.
The wool makes the soil healthy after decomposition.
Also, it helps retain moisture, which is very beneficial for plants that love moisture.
Besides, it also aids in drainage.
For a longer stay, place the wool over cardboards or newspapers.
12. Treated mulch
Treated mulch is recycled from plastic and turned into biodegradable mulch.
You can use it at the bottom of raised beds for many plant types, like veggies and flowers.
These materials have anti-weed components used for weed control, even if the mulch gets dissolved and is no longer visible.
The product is a bit more expensive than other mulches.
But, it gives the same results as the other mulches.
A good point is though the product has anti-weed components, they don’t have any chemicals to kill weeds.
So, your soil and plants will be safe.
13. Hardware Fabric
If your areas are filled with rodents, hardware fabric is a good choice for you.
It is a strong stainless steel mesh wire used for construction purposes.
It will get rusted and break over time.
But, this will give you at least 10 years of support.
Buy the hardware cloth according to the size of your raised bed and put it at the bottom of the raised bed.
Staple it at the sides.
Hardware cloth has various sizes and thicknesses.
Consult the buyer before use.
These mesh wire hardware clothes also allow beneficial earthworms to enter the soil and make it airier.
14. Landscape Fabric
If you want a better option, spend money and opt for landscape fabric.
A big advantage of this fabric is that it is long-lasting and resistant to decomposition.
Like the hardware fabric, landscape fabric also lasts for nearly 10 years.
This material can also cover your raised bed soil if needed.
Just create some holes for air circulation.
Putting the fabric at the bottom of the raised bed and over the soil suppresses the weed growth greatly.
Besides, this material has good water permeability.
Pour water directly over the cloth, and it will pass through it.
While buying, check the fabric closely and don’t confuse it with plastic.
Landscape plastics help control weed growth but don’t allow the water to drain like the fabric.
Burlap is a great alternative to landscape fabric.
It is not a non-biodegradable product like landscape fabric.
It will ultimately decompose, but it will take many years to decompose.
Burlap is an eco-friendly product that greatly suppresses weeds and allows water to pass through.
It is created with jute fibers and doesn’t harm your plant or soil.
The only disadvantage of this product is its fray. The edges get frayed easily.
So, it is difficult to cut or tear.
The edges wear out easily whenever they are cut, torn, or exposed.
16. Food-grade plastic
This material is best if your ground soil gets contaminated.
Food-grade plastic will block the contact between the ground soil and the soil of your raised bed.
For drainage, create some holes for easy water passage.
The plastic is heavy and will close off the connection between the ground and the bed’s soil.
When you completely block the connection, your raised beds work as pots.
That is why the holes will work as drainage holes.
You can also use carpet as an alternative to the options mentioned above.
But, you must be careful about the type of carpet you use.
Maximum carpets are made of plastics that don’t decompose, release bad chemicals into the soil, hinders drainage, and disturbs the plant roots.
The best choice would be natural carpets made of organic materials like jute, cotton, or hemp.
They will suppress the weed growth and take a few years to decompose.
Staple the carpet to the raised bed on different sides for a strong base.
You can also stick the carpet outside the bed edges to suppress the weeds from the sides.
Creating a lining between the ground and the raised bed soil is not mandatory. However, it can show better results in your plants. As you can see, several materials are used in the bottom of the raised beds. Some are easily available, and some are expensive.
There are alternatives for other products, and you can use some together. For example, you can put wool over newspapers or cardboards. If you want the base to last longer, go for a little costly product like landscape or hardware fabric.
If you want something eco-friendly, cost-effective, and easily available, try newspapers, cardboards, rocks, coconut fiber, burlap, etc.