Raised bed garden is an excellent choice if you have a bad kind of soil in your garden, or you wanted to decrease the level of work you are putting for growing your own veggies.
If you are a beginner, you definitely have lots and lots of questions about making your first raised bed. Like, can I put a raised bed garden on grass? What can I put under a raised bed garden?
In this post, I’m gonna answer these specific questions in detail. Keep reading to find out what you should do before filling your raised bed garden with soil.
Putting a raised bed garden directly on grass is not a good idea. You should always put some kind of cardboard, plastic, newspaper, or landscape fiber at your land before adding any kind of soil.
Why putting a raised bed garden on the grass is not a good idea?
Before putting your raised bed garden in your area of selection you need to take care of some important factors. Is your area is cleaned of grass and most importantly weed?
If not, grass and weed will grow through the inches of your raised bed soil. That will be a big headache for you. You should cut the grass and weeds and perform a little procedure to kill them for good. The procedure is named as Soil Solarisation.
In this procedure, the area of your selection should cover with a plastic sheet and leave there for at least six weeks. There is no use of the chemical in this procedure.
The plastic sheet will trap the sunlight in it, which will increase the temperature of the soil. An increase in temperature kills the grass, weeds, and pests too. That will clean your area from grass, weeds, and pests.
Before performing soil solarisation, you should till the area, select a sheet with a thickness of 1.5mm and do not choose a damaged sheet because that will release the sunlight and temperature will decrease. If weeds and grass grow after 6 weeks, that means your soil solarisation is not working.
Soil solarisation could be harmful to good kinds of microbes. But we are adding our own soil in a raised bed garden, so that is not a problem for us.
Watch Soil Solarization Demonstration
What do I put on the bottom of a raised garden bed before soil?
As I mentioned above, the only reason to add something on the bottom is to stop growing weeds or grass in your raised bed. And it is very important to keep weed out of your raised bed for the magnificent growth of your plants.
1: Landscape Fiber.
This is a special kind of fiber that is made of mostly recycled material, linen or polyester. This fiber has numerous holes in it for drainage and water transportation. You can use this fiber to line the bottom of the raised bed. There are so many pros of landscape fiber:
- It will definitely discourage the weeds and grass to grow.
- Good kind of fiber can last for years, so for almost 10 years, your raised bed is safe from weeds.
- Landscape fiber is environmentally friendly. Because it is made of recycled plastic.
Here are a few cons of landscape fiber:
- You cannot till your raised bed soil very deeply. It can destroy fiber.
- Good kind of worms and microbes cannot enter your raised bed soil from the bottom because of this fiber.
- Some roots of plants can destroy your landscape fiber in search of water and nutrients.
You can put old newspapers, magazines on the bottom of the raised bed garden. Sure it is not very long-lasting as landscape fiber. But still, something is better than nothing. Put the newspapers on the bottom in a manner so the edges of newspapers overlap each other. Newspapers will also reduce the growth of weeds. After some time, the newspaper will decompose and add a layer of humus in your raised bed soil, which is a plus point of using newspapers.
Cardboard is the same as newspapers. The only difference is, cardboard can last a little longer as compared to the newspaper. Cardboard also works as a weed barrier on the bottom of the raised bed. After the decomposition, they will also add humus in the soil.
4: Any Kind Of Plastic.
If you have any kind of plastic at your home, you can put that on the bottom. Any kind of plastic will be a great weed barrier, but it is not very good for drainage. If you are using plastic instead of landscape fiber, then you need to drill some holes in it for drainage. Plastic will last years and stop weed germination.
5: Concrete slab.
If you think the soil where you are putting your raised garden bed is terrible, has a lot of stubborn weeds and the soil is no use for gardening, you can build a concrete slab and put that on the bottom of your raised bed. Here are a few things you should remember before putting a concrete slab on the bottom of your raised garden bed.
- You need to drill some holes in concrete slabs with a drill machine in the concrete slab for drainage.
- Before adding soil, add a layer of small stones or pebbles on the top of concrete slabs.
- Now add a very thick layer of the soil, a good soil mix on the top of the pebble layer, because some plant roots go very deep, they will need a thick layer of soil for better growth.
- The concrete slab would be a great weed barrier because it will last for many many years.
- Add a good compost every year for better growth of plants.
If your soil is a little bit better, then don’t use concrete at the bottom. Here are a few cons of using concrete
- A concrete slab can change the pH of the soil because concrete is made of cement and cement is made of man-made limestone. And limestone can raise the pH of soil.
- Water can drain so fast through the holes in concrete slab because it has no water holding capacity.
- Plants with deep root systems will not take concrete slab very well.
6: Gopher Wire.
Do not confuse yourself with gopher wire and chicken wire. They are two different kinds of wires and play different roles. Always use gopher wire on the bottom of your raised bed to keep pests out of your garden bed. There is no drainage issue in using gopher wire. Gopher wire surely can keep pests out of the garden bed, but weeds can find a way through it. You can buy a gopher on amazon here.