In previous posts, I talked about raised garden beds and their benefits. Gardens don’t always have to be at ground level and so many gardeners prefer to use the beds. I’ve gotten some feedback on the posts and a few questions, and I will address one in this post.
Raised beds don’t need to have a bottom but depending on certain considerations, you may need to add one. Your raised bed might need a bottom if you have pest problems or you experience lots of water in your garden. So really, it’s an automatic yes, especially because it helps when your raised soil mixes with the soil on the ground, but it helps to keep your plants safe.
This post will show more on what you need to know about raised beds and their bottoms, and other options you might want to consider instead of placing a simple bottom.
What is A Raised Garden Bed?
A raised-bed garden is simply a planting area that’s higher than the level of the surrounding ground. They keep pathway weeds from your garden soil, prevent soil compaction, provide good drainage, and serve as a barrier to pests such as slugs and snails. The sides of the beds keep your valuable garden soil from eroding or washing away during heavy rains. Raised beds seem to be the most ideal choice. Some of its benefits include:
- Save time
- Soil development
- Reduces weeds
- Longer growing season
- Deterring Pests
- It is Ornamental
The main aim of building raised beds is to be allow you improve the soil by growing in a custom soil mix that is better than the one already on the ground. The soil used to make the raised bed will usually be lighter, fluffier, hold more water and have more nutrients. Because most flowers don’t have very deep roots coupled with a situation where there is a big difference in soil textures between the soil on the ground (hard) and raised bed soil (soft), the roots will grow thicker and denser in raised mix and become thinner in the existing soil. Look into which plants you plan on growing and see how well they do in soil as deep as your raised beds.
Do Raised Beds Have A Bottom?
As has been mentioned, a raised bed is a box with no bottom or top—a frame. So raised beds usually have nothing on top of or below them. However, for several reason (usually protection), you may have to put some material in either of these spots.
So, if the raised bed is sitting on the ground with ideal conditions, then you do not need to place anything in the bottom of raised beds. In fact, allowing the existing soil mix with the soil that you add to the bed will improve the rooting of the plants that grow in the bed.
A bottom would only be required if you are protecting the surface below the raised bed. An example might be if you have severe gopher problems and others pests that come from below.
In that case, you might want to place/cut wire mesh or screen (hardware cloth) at the bottom of the bed, cutting corners to fit around corner posts, to prevent them from tunnelling into the bed
Also, you don’t need to put a hard bottom in your raised beds but many people use a weed fabric if they have severe weed issues, and use it to keep weed seeds from sprouting in the soil already on the ground.
Weed fabric will block weeds while still allowing drainage. Weeds can dig through quite a soil to reach the top, especially if the soil in the raised bed is soft and light (Which is usually how will be).
You can use almost anything to prevent weeds from making it to the top of your bed, including cardboard and old newspaper.
To guard against poor drainage, you may want to use a more deliberate hard bottom, you may want to consider using rocks. Many plants require well-draining soil, so placing rocks in the bottom of a raised bed will help create additional drainage space below the soil.
Moisture stress of the soil can cause the root to rot and damage or kill delicate plants. As soil settles over time and becomes compacted, the rock at the bottom of the bed allows space for excess water to drain away from plant roots.
Crushed rock or pea gravel will work well at the bottom of a raised bed to improve drainage, particularly in beds more than 18 inches tall or where the bed is in an area of the yard with poor drainage.
Once the raised bed site is prepared, place the crushed rocks or gravel into the framed space. Spread the rock by hand, or with a metal rake, until you get a uniform depth of 2 to 3 inches across the bed.
Add good quality topsoil on top of the drainage rocks until it reaches just below the edge of the raised bed. If you’re putting raised bed right up against your house (or other structure) you may want to put some water-impermeable fabric on the bottom as a slope to direct drainage away from the house.
Alternatively, you could use materials that don’t let the water dry out too quickly, if you stay in an area that gets lots of sunlight. Some of them include dry wood, that is light, or chunks of paper. These will help retain some of the moisture for some time while draining the water from the beds, so it doesn’t dry out too quickly.
Even with the benefits of drainage rocks and other material in the bottom of a raised bed, make sure to regulate the amount of water you give to your beds to avoid over- or under-watering.
Check the water requirements on the package included with plants you have purchased and follow those instructions. If you’re not sure, follow the rule of thumb to water the plants only when the top 1 to 2 inches of soil feel dry.
Keep in mind when placing anything at the bottom of the bed the length to which the roots of your plants may grow to.
If your plants are going up to a certain point, try to plan the amount of soil you will put in the raised bed based on that, or you can reduce the amount of the things at the bottom so that the roots are able to get into the existing soil.
Alternatives to Raised Beds
If for some reason, you don’t want to compromise your garden by putting a bottom, you can always just use these other methods to plant. They all have their advantages and disadvantages so be sure to consider everything necessary before you start.
Elevated raised bed gardening
Gardening in elevated raised beds is basically a hybrid gardening technique. It’s a mix of container gardening and raised bed gardening. Think of it as a raised bed that is placed on a platform rather than being placed on the ground soil.
Soil is placed in a container similar to what it would look like simply as a raised bed, and you can garden as usual. This will help you let go of such issues as gofers.
So you elevate your bed to the point that some pests can’t get to it again, or wouldn’t want to as it’s in the open.
Traditional bed gardening
If you have a large, full-sun garden plot that has rich, well-draining soil, planting directly in the ground may be the easiest way to start your garden.
However, if your garden site has compacted clay or very sandy or rocky soil, you can spend the time and effort to improve it by adding a lot of organic material.
This is the same as what you do to the soil of a raised bed which is to get the soil fit for planting in the first place. If your soil is already good, you can save yourself some time and simply work on the soil as it is.
It all depends on the area and conditions of the are where you place your raised bed, that you may or may not need to put a bottom in your bed.
If you have severe pest problems, irrigation issues, weed issues, or other considerations, you may want to put the bottom to prevent all them from giving you concerns and disturbing plant growth.
It could be wire mesh or screen (hardware cloth), rocks or gravel, paper, wood or anything else. As long as it fixes your issue. Also, consider the plants you are growing and make sure placing a bottom in your raised bed won’t do more damage to your plants than the other reasons you placed a bottom.
I hope this blog post was able to answer your question. If you got value from this article then consider subscribing to be notified of future posts.
Remember folks; You Reap What You Sow!