You’re thinking about it.
How nice it would be to grow some plants in attractive planter boxes.
But if you decide to use them, would these planter boxes need a bottom?
Planter boxes need a bottom if you’re going to place them on a surface that could get stained. This could be your wood patio, deck, or roof. They don’t need a bottom if you’re going to place them over good quality soil in your garden.
In this post, I’ll help you understand situations where it makes sense that your planter boxes have a bottom. I’ll also give you information on the materials you can use for the bottom and how to use them.
Let’s take a look.
1. Attack by burrowing pests
Your planter box could be attacked by burrowing pests such as gophers that reach the plant roots through the soil. The best way to avoid this problem is using a planter box with a bottom.
It’s best to use a wire mesh or stainless steel mesh that these pests can’t get through. You’ll still get good drainage and beneficial organisms through the mesh.
2. Infestation of weeds or grass
Weeds can be a common problem if you put the planter box directly on the soil. They can grow through the soil and into the planter box.
Using a planter box with a bottom helps keep such weeds out. If your planter box has a wood bottom that would work fine. Otherwise, you can use a weed fabric or landscape fabric to keep the weeds out.
Such material can also help keep the grass out of your planter box if you place it on a location that has grass growing. You can avoid the work of pulling out the grass or getting rid of it if you use a bottom.
3. Drainage problems in the garden
If the planter box does not have good drainage, the plants will face overwatering as the water collects at the bottom. This would cause fungal issues such as root rot that would destroy the roots.
The drainage could become a problem when the planter box is placed on soil that has a lot of clay causing poor drainage. It could also be a problem when the planter box is placed on a slope where the water cannot drain.
You can place a bottom under the planter box that will ensure the water runs out from the side of the box. Some materials that would work well would be wood or plastic.
You can build the bottom at an angle so that the excess water can flow out from the sides of the planter box.
4. Protecting your floor from stains
Planter boxes will add beauty to your deck, patio, or roof where you place them. If the planter boxes don’t have a bottom, the soil will stain the floor.
The best way to avoid this problem is to use a planter box with a wood bottom. I would recommend using an elevated planter box at such locations.
It will protect the floor from stains and you can collect the water that flows out from the drainage holes at the bottom. Use a tray to collect the water that you can reuse for your plants.
5. Poor soil in the garden
You can place the planter box in the garden on top of the soil. You don’t need a bottom if the soil is good. The plants will be happy to grow into the soil.
The problem could happen if the soil in your garden is not healthy. This could be because it contains a lot of clay that causes drainage problems. Or it could be toxic because it contains chemicals left by pesticides and fertilizers applied on the lawn earlier.
It’s best to use a wood bottom for such planters that would keep the soil in the planter box separated from the garden soil.
6. Moving your planter box
If you have small planter boxes, you could move them around. You may need to do this if there’s a better location where the plant could get sunlight.
You may need to move the planter boxes to a location that is warm when the night temperature drops in fall. You may even move it indoors and keep the planter box in your basement or garage.
This would only be possible if the small planter boxes have a wood bottom so the soil does not fall out. You could even keep the planter box on a moving tray, so it’s easier to move around.
What is the best bottom for a planter box?
The best bottom for a planter box would depend on the benefit it provides for your particular situation.
The simplest option is to buy a planter box that comes with a wooden bottom. This works well when you want to place the planter box on your patio, desk, or floor.
The wood bottom will protect the floor surface from the staining caused by the soil.
Pro tip: Even if you have a planter box with a wood bottom, it’s good to line the planter box with material such as plastic or landscape fabric for additional protection against weeds, prevent leaching of the soil, and improve the life of the planter box.
A plastic sheet is a good option to use as a planter box’s bottom when you’re placing the planter box on grass. Or on soil that could contain potential weeds that would grow into the planter box.
Wire mesh or steel mesh is a good option when you’re placing the planter box outdoors in the garden and want to protect your plants from pests like gophers that would burrow into the planter box.
Weed fabric or landscape fabric works well to keep the weeds away from the soil in your planter box. Make sure to staple it well to the planter box as it could shift because of the weight.
If you’re looking for a really cheap and readily available option, you could use newspaper or cardboard at the bottom of the planter box.
These work well to smother the weeds and grass growing on the soil. They also decompose over time and add organic matter to the soil.
How do you add a bottom to a planter box?
Adding newspaper or cardboard
Adding these materials is the easiest to do. You just add layers of the materials on the bottom of the planter box.
Make sure that the sheets are overlapping each other so there are no gaps through which the weeds or grass could grow.
Using plastic or landscape fabric
These materials are flexible and you can add those to the bottom of the planter box. The problem is such flexible material can shift as the soil absorbs moisture and dries out.
It’s best to fix these materials to the planter box by using a heavy-duty staple gun. You can staple the material to the sides of the wood planter box every 6 inches.
Adding wire mesh or cloth
These materials are hard and can take a little bit of work to add to the bottom of the planter box. If there are multiple small sheets, you can attach them together using plastic ties.
To secure the sheets to the bottom of the planter box, you can use landscape staple so they are attached firmly to the ground.