Raised garden beds help plants grow in areas where the soil is too sandy or alkaline. But to take advantage of these structures, there's one question you have to answer: "How deep should a raised garden bed be?" Generally, the optimum height for a garden bed has to be 8 to 12 inches. However, some plants do well in lower or higher measurements (6 inches or 18-36 inches). In this article, Savana will give you more information about this.
Raised Garden Bed Dimensions
1. Depth
How deep should the raised bed be? The answer depends on the type of plants you want to grow. As you'll see, tomatoes and other long-rooted plants need more vertical clearance. Meanwhile, low to medium depths are fine for strawberries and other species.
Check out some raised garden bed heights for typical flora below.
- 6-8 inches: lettuce, mint, oregano, basil, parsley, and other herbs
- 12-18 inches: Broccoli, celery, cabbage, bok choy, strawberries, potatoes, garlic, corn, arugula, onions, spinach
- 18-24 inches: Beets, carrots, kale, squash, cucumbers, peas, radishes, beets
- 24-36 inches: Okra, watermelon, squash, asparagus, parsnips, tomatoes, artichokes
You must follow the above advice, because if the bed is too shallow, the vegetation will have less nutrients and drainage will suffer.
Besides plant type, there are a few other factors that can affect the height of a garden bed:
- Gardeners with wheelchairs should have beds that are at least 24 inches deep.
- If you have knee or hip problems, don't let your height drop below 36 inches. This is especially important if you have a large yard that requires heavy fertilizing and harvesting.
- After the plants, soil, and everything else are in the bed, there should be 2 to 3 inches of mulch left.
- The deeper the garden bed, the more soil you will need to buy. When considering the cost of a gardening project, the amount of soil is critical.
For example, a garden bed that is 6 feet long, 4 feet wide, and 18 inches deep requires 36 cubic feet of soil. Meanwhile, a garden bed of the same length and width but 12 inches deep would require 24 cubic feet of soil.
Therefore, it is more economical to adopt the above lower limit for the required height.
That said, a wider soil depth will help the plants retain water better, reducing the amount of work required to care for them.
- If the garden bed is on a hard surface, the ideal depth is 2 feet.
- Local laws may limit the height of plant boxes, especially if your garden is close to a road.
2. Width and Length
In addition to the depth of your raised garden bed, width is also important. Make the bed 3 feet wide so your hands can easily reach the sides of the bed. Up to 4 feet is the limit you should aim for.
Also, there is no limit to the length of the garden beds. You can build boxes as long as 4 feet or even 20 feet, however you like.
Spacing Between Beds
Another thing to consider is the distance between garden beds. In general, allow at least 1.4 feet or 45 centimeters of free space between plant boxes.
You don't want them to be too close together; there should be enough room to walk and move gardening tools like shovels, fertilizer, and soil.
This makes caring for your plants more manageable, and people don't step on garden beds while walking.
Other Considerations for Choosing Garden Beds
- Place the plant in a sunny location without strong winds. Long beds should run from north to south.
- Study the height of the plants to line them up correctly. Plants of the same height should be grouped so that taller shoots do not block shorter shoots from receiving sunlight. Taller and heavier plants will also need to be secured with stakes or trellises so they don't fall over.
- You can buy ready-made garden beds from stores like Savana, or build your own. If you go the DIY route, use unpainted wood that hasn't been pressure-treated. Stone, brick, and cement are also available materials. Whatever you choose, make sure the bed is rot-resistant.
- If the bed is taller than 12 inches and longer than 6 feet, it will need lateral supports to handle the weight of the soil. Similar to garden beds, you can buy cross braces or use wood or aluminum.
- The drain hole should be near the bottom of the equipment box. Check out this article to know what you should put in the bottom of your raised garden bed.
- Before setting up a garden bed, gardeners should dig the soil in which to hold the plants to check for rocks and anything that would hinder the plant's root system. This is called double mining.
- Double digging also helps determine if soil PH needs to be adjusted so one can create the optimal environment for vegetation to grow.
- Deep grow beds should have the proper composition to make the soil rich in nutrients. At the bottom of the bed, you can put straw, leaves, and cardboard to make compost. The ideal composition is 30 percent compost and 10 percent potting soil, with the rest being topsoil.
- Vegetables should be fertilized with a water-soluble fertilizer once a month. Other times to fertilize are at the beginning of planting and mid-season.
- Remove weeds from your garden before you build a raised bed, and whenever they appear (usually in the spring).
Conclusion
By now, you should know the answer to "How deep should a raised garden bed be?" No matter what kind of plant you want to grow, it is important to consider the size of the vegetable or pot.
