Are you annoyed by pests in your garden? Or maybe you just want to protect your plants from cold. Either way, a cover for a raised garden bed can help to keep your plants safe and give you a better harvest.
So, how do you cover a raised garden bed? To cover a raised bed, you will need two things: a frame and a material to cover the frame. You can make your frame out of wood, plastic, or metal. The cover material could be netting, plastic, glass, mesh, or row covers.
Of course, the cost to build a cover for your raised garden bed depends on the materials you use. In this article, we’ll take a closer look at some ways you can cover a raised garden bed. Let’s begin.
How to Cover a Raised Garden Bed
When you make a raised garden bed cover, you will need to choose a material for the frame and a material for the cover.
There are 3 basic choices for the frame, and 5 basic choices for the cover. This gives you 15 different combinations choose from!
We’ll start with the frame materials.
Materials for Frame
First, you need to choose a material for the frame. This is the first part you will build when you make your raised garden bed cover.
I’ve outlined the three basic choices below, along with the pros and cons of each one.
Wood is a common material for raised garden beds. Here are a few options if you choose a wooden frame:
- Stakes – these are often used to support tomatoes. You can drive several stakes into the ground around the edges of your raised bed. Then, lay a cover over the stakes (plastic, mesh, or row covers would all work). Use twine or wire to tie the cover to the stakes. You might also be able to find bamboo stakes, which are strong and durable.
- Sticks – this is the most cost-effective option. However, it can be hard to find enough sticks that are straight and strong enough for the project. If you can get enough of them, use them like stakes.
- Wooden Boards – this is the most expensive option. However, boards make for a stronger structure. You can cut the pieces down to size depending on how big your raised bed is. Here are a few choices of wood for boards:
- Pine – a soft wood, often used to make furniture. It does not resist the elements, so it is not so good for outdoor projects. In most cases, untreated pine rots within a few years outside.
- Oak – a hard wood, oak is stronger than pine. Oak lasts longer than pine when used for outdoor construction.
- Cypress – a soft wood, cypress resists rot when it comes in contact with wet soil. Cypress has natural oils that protect the wood so that it can resist damage from decay and insects.
- Cedar – a soft wood, cedar holds up well outdoors. Cedar also contains natural oils that help to protect it against rot and insects. Eventually, the red appearance of cedar will fade to gray over time, before the wood rots. Cedar is a very expensive choice of wood.
- Redwood – a soft wood, redwood is one of the longest lasting you will find. Even in the outdoors when exposed to wet soil and insects, redwood is great at resisting the elements. Redwood is expensive, but it can last up to 30 years.
The biggest enemy of wood is time. Eventually, even the best rot-resistant wood will break down due to damage from insects, sun, heat, and moisture.
If you use plastic or glass as a cover, it will protect the wood from rain. However, the humidity in the air (trapped under the plastic or glass) can also make the wood rot.
You can treat the wood with a stain or sealer to make it last longer. However, you might be worried about using chemicals near your garden, which I totally understand.
Luckily, there are some more natural options. For example, Gardener’s Supply Company has a clear water proofer made from juniper.
If you want a more natural-looking cover for your raised garden bed, then go for a wood frame. It may not last as long as plastic or metal, but you can treat the wood to extend its life outdoors.
Avoid older “recovered” wood from pallets, railroad ties, or demolition projects. Some of this wood is treated with chemicals like creosote and CCA (chromated copper arsenate), which you don’t want in your garden.
If you want a lightweight, long-lasting frame for your raised garden bed cover, then plastic is the way to go. Here are a couple of choices if you opt for plastic:
- PVC pipe – PVC (polyvinyl chloride) is a plastic polymer used extensively in home and garden projects, including plumbing, drainage, irrigation, and gardening. PVC pipe can be pretty stiff, depending on the thickness. This makes it a good choice for construction, since it is hollow (less weight) and resistant to rot (unlike wood).
- Plastic boards – not to be outdone by wood, plastic also comes in board form. Often, plastic boards are made from recycled material. You can cut them to whatever size you need for your raised bed, just like any wooden board.
If you pair a plastic frame with a glass cover, you won’t have to worry about damage from weather or time. That particular combination will hold up for years to come.
One drawback of plastic is that it does not have the natural appearance of wood.
If you want a heavy-duty frame that will resist rot, then metal is the way to go. Here are a few ways you can put metal to use:
- Poles – you can drive metal poles into the ground just like wooden stakes. The only difference is that metal poles will last longer. Also, sturdy metal poles will hold more weight that wooden stakes. This is useful if you choose a heavy cover, such as glass.
- Fences – if you take down an old fence, you can use the posts to help you build the frame for a raised garden bed cover. You could even use the chain link to keep larger animals (like deer) out of the garden.
- Tomato cages – this is a cool idea. All you have to do is support the plants in the corners of your raised bed with tomato cages. Then, you can drape plastic or a row cover material over them. Secure it in place with twine, clothespins, or any fastener you have available.
One drawback of a metal frame is that it can be quite heavy. Also, most untreated metal (such as iron and copper) will rust or tarnish over time as they react with oxygen in the air.
Materials for Cover
Now that you’ve chosen a material for the frame, it’s time to choose a material for the cover itself. The cover will go over the frame, and will do the real work of protecting plants from pests or cold.
I’ve outlined the five basic choices below, along with the pros and cons of each one.
Netting is nice and light, so it is easy to remove if you need to access your raised bed. Netting is also a good choice if you need to keep animals out of your raised bed.
The holes in the netting are small enough to keep birds and squirrels out, but large enough to let bees in. This means that the plants in your raised bed will still get the pollination they need.
However, this also means that other flying insects can get into your raised bed. If you have trouble with cucumber beetles, moths, and other flying pests, then netting may not be the best choice.
Netting won’t do anything to protect your plants from cold, either. So, if you are worried about a late spring frost hurting your plants, then consider another cover.
Finally, you may find that sticks and leaves get trapped in the holes in netting after a strong wind or thunderstorm. If you live in a windy area and don’t want to deal with this nuisance, then choose another material for your cover.
Plastic is a common choice for the cover of a raised garden bed, and for good reason. Plastic is commonly available and serves multiple purposes:
- First, a plastic cover will keep both animal and insect pests out of your raised garden bed. This will give you a better harvest from the same number of plants.
- Also, a plastic cover causes a natural “greenhouse effect”, warming the air and soil under it. This is helpful if you want to start plants in a raised bed early while protecting them from frost.
- Finally, a clear plastic cover will allow sunlight through. This means plants that need full sunlight can do well under a plastic cover.
On the other hand, these advantages could also be viewed as negatives. Here’s why:
- First, a plastic cover will prevent bees from pollinating your plants. You will need to either pollinate by hand, or open the cover to let the bees (and other pests) in.
- Also, a plastic cover can overheat plants on hot days. This is especially true when the sun is strong and there are no clouds.
- In addition, the humidity and heat trapped under a plastic cover can make a wood frame rot faster.
- Finally, certain types of plastic will break down over time when they are exposed to sunlight. They might start to crack or tear depending on the material and the intensity of the sunlight.
Plastic is probably not the best choice if you live in a hot climate or if you want to use a wood frame.
Glass is much heavier than plastic. However, it shares many of the same benefits as a cover for your raised garden bed:
- A glass cover keeps animal and insect pests out of your raised bed.
- A glass cover keeps the air and soil under it warmer.
- A glass cover allows sunlight through.
However, glass shares many of the same drawbacks as plastic:
- A glass cover will prevent bees from pollinating your plants.
- A glass cover can overheat plants on hot days.
- A glass cover will trap humidity and heat, which will cause a wood frame to rot faster.
Unlike plastic, glass will not break down from exposure to sunlight. Glass will last much longer than plastic unless it gets broken by a falling tree branch.
However, glass is heavier than plastic and it is harder to work with. Glass is less flexible, so you cannot curve or bend it like you can with some plastic coverings.
Glass is a good choice if you want your raised bed to look more like a greenhouse or cold frame.
A mesh material made of metal has several advantages:
- It keeps animal pests away, including birds, squirrels, and deer.
- It is the most breathable out of all the cover materials, so your plants are less likely to overheat.
- It is flexible and easy to work with, so you can bend it into the shape you need.
However, there are some drawbacks to using mesh:
- A mesh will not protect your plants against cold, unless you drape plastic or row covers over it on a cold night.
- A mesh will not protect your plants from insects, since the holes are big enough for them to get through.
- A determined animal might be able to bend it to get in (for example, raccoons).
Two mesh materials you might use are rabbit cage and chicken cage. Rabbit cage has smaller holes, so it will keep smaller animals out of your garden.
You could use a mesh material as a cover to allow your plants to breathe. Then, you could put plastic or row covers over the mesh to add overnight protection from cold and frost.
Just remember to remove the extra covers in the morning if the next day will be hot. Otherwise, your plants will overheat.
Row covers such as Agribon are used to protect an entire row of plants from cold, animals, and insects. However, you can also use it as a cover for your raised garden bed.
Row covers also allow some light through to your plants. The amount of light that gets through a row cover varies, depending on the thickness.
Just remember that some clever animals might be able to get past row covers.
Other Considerations for a Raised Garden Bed Cover
Here are a few things to consider when choosing frame and cover materials for your raised garden bed:
- Hinges – do you want to be able to prop the cover up on a hot day, to give your plants air and relief from the heat? If so, hinges would be useful.
- Pollination – you might be able to hand pollinate your plants. However, if not (or if you don’t want to), then you will need to remember to open up the cover to allow for pollination.
- Chemicals – be careful about using recycled materials that may contain chemicals that can leach into the soil and end up in your vegetables.
- Pests – don’t be afraid to choose a cover that does not keep pests out. There are other ways to discourage pests.
For example, hanging CDs from strings to scare birds away, or using companion planting to repel certain insects. Using a raised garden bed liner will also prevent pests – you can learn more about them here.
Now you have some ideas for how to cover a raised garden bed. The decision is yours, depending on what materials you have available and how much you want to spend.
You might be interested to read about more ways to cover plants in my article here.
I hope you found this article helpful. If so, please share it with someone who can use the information. I hope your raised garden bed cover helps you to get a good harvest for years to come!