How Deep Should Raised Garden Beds Be?

When deciding on a raised garden bed, one of the major factors is the depth requirements of the raised garden bed. If you’re placing your raised bed on a patio or a terrain where the soil underneath is not conducive to growth, then it is important to grow your plants within the parameters of the bed itself. A raised bed should be able to blend in well with its surroundings as well as adequately support the roots of your plants. The required soil depth depends on the types of plants grown, the soil conditions, and desired aesthetic. Other important considerations include the shape, size, and material chosen for the raised garden bed. Since there are a dazzling array of designs available worldwide, choosing one can be a tough decision to make. 

However, the large variety of patterns available guarantees that there is a match for every type of landscape, budget and style. A raised bed can either be informal or formal, depending on your preference and garden situation. We recommend displaying vegetable gardens in modern, industrial metal beds, which can prove to be an attractive focal point of your garden, and significantly brighten up dull spaces or outdoor dining areas. It is important to keep in mind that the size of the bed should be proportional to the space around it. If you have limited space, it is best to buy modular raised garden kits, which will allow you to customize your beds based on your available space. This article examines the soil depth requirements for various types of yards and plants.  

Drainage: Whether it be an irregularly-shaped perennial border garden that sits behind a dry-stone wall, or a metal raised bed in a vegetable garden, one should always consider the depth of the raised bed carefully. A raised bed does not always require a significant depth for it to be effective. They should have at least 8 inches of soil depth to accommodate the root systems of plants, because the majority of plant roots require 6 – 8 inches of soil for healthy root growth. A depth of 8 – 12 inches will suffice for most gardening situations. 

Because of  the excellent drainage properties of raised beds, it is possible to grow an abundance of vegetables in a limited amount of space. In cases where drainage is an issue, or if the plants that you are planning to grow prefer an environment with drier soil, then the depth of your raised garden bed can be taller, which can then be filled up with a porous growing medium.

Material: The material you use for a particular raised bed should be durable, attractive and stable. It is important to consider the material of your garden bed, which determines how well it blends in with the landscape. The sides of the bed lend structural support to the and help contain the soil in a particular space. The sides of raised garden beds can be metal panels, wood, or brick and stone. While it is important to consider the depth of your raised garden beds when browsing for raised garden bed designs, it is also important to consider the material of your garden bed. 

Traditional metal panels, while easy to install, can rust over time, diminishing its attractiveness and usefulness. Wood will rot in as little as one season. Stone and concrete blocks can be expensive to install. Also, many gardeners do not want the hassle of buying raw material and assembling them for a DIY raised garden bed project. We recommend Vego Garden beds for an easy solution. Vego raised garden beds are made of a specialized rust and corrosion resistant metal and lend a clean, modern aesthetic to your garden. Our kits are easy to assemble, and complete with heavy duty rubber edging along the top to ensure a safe and fun experience. 

Double Digging: Some gardeners choose to dig below the ground using their shovel to create more space for their roots, especially if they have a crowded or shallow garden bed. This process, known as double digging, can be time consuming and arduous. Vego Garden beds are tall enough that you don’t have to dig into the ground. You can simply place your raised bed anywhere in your yard after clearing the ground of debris. 

Gardeners should slightly overfill their gardening beds, because the soil will compact over time with watering. As a tip, you should add an extra 2 inches of soil over your garden bed, and water the soil to see how much it compresses. 

Vegetable Beds: On the other hand, when it comes to vegetable beds, the bed must be approximately 12 to 18 inches deep to ensure adequate depth for the roots of your plants. This is especially important if your raised bed is placed on cement or the patio, which will inhibit roots from growing deeper into the ground. Below are the root depth requirements of a few common garden plants. Since our garden beds are 17″ and 32″ deep, they are deep enough to cultivate a medley of vegetables, including those with deep root systems. A deeper bed also allows for more moisture retention, leading to less watering and chance of drying out.  

The following plants have 12 - 18″ roots

• Garlic, onions, chives
• Lettuce, brussels sprouts, spinach
• Corn, cabbage, radishes 
• Strawberries 

The following plants have 18 - 24″ roots

• Beans, peas
• Cantaloupes, squash, eggplants
• Carrots, turnips, beets
• Potatoes

Below are plants with deeper systems of 24 - 36″ roots

• Artichokes, asparagus
• Parsnips, rhubarb
• Sweet potatoes, pumpkins
• Watermelons 

Plant Arrangements:

When planning out the components of your raised garden bed, it is important to orient your crops so that taller plants don’t block shorter plants from receiving sunlight. Beds should face South horizontally, which optimizes sun exposure across the bed and prevents neighboring plants from shading each other as the sun moves from East to West. If you are growing a variety of plants, you can orient your bed vertically (North to South), positioning the taller plants in the back to prevent them from shading shorter plants. Do not situate your garden bed in windy locations or near wet and marshy areas.

It is important to know the height of each crop at maturity in order to plan out your planting arrangements. To illustrate, shorter plants such as lettuce and radishes should be planted on the south side, while the tallest plants should be planted on the northern side of the area. If you have a trellis, it is important to keep it near the rear wall, as those plants can block out a large amount of light. Below are the heights of some popular vegetables at maturity: 

Vegetable	Size at Maturity	Vegetable	Size at Maturity
Artichokes	4' - 5'	Leeks	12" – 24"
Arugula	8" - 10"	Lettuce	6" – 12"
Garlic	12" – 24"	Onions	8" – 24"
Corn	4' – 8'	Peas	2' – 6'
Beans (lima)	24" – 36"	Watermelon	12" – 36"
Beans (pole)	8' – 12'	Parsnips	6" – 18"
Tomatoes	2' – 8'	Potatoes	12" – 30"
Cabbage	12" – 18"	Turnips	6" – 12"

Bending Over:

If you experience mobility issues, back strain, or simply dislike bending over, a taller raised garden bed will improve your gardening experience. Our extra tall 32″ garden bed kits significantly reduce back strain when you are tending or harvesting your garden. Whether you are a more experienced gardener or a beginner, we definitely recommend you invest in a raised garden bed to reduce the toll that straining your back can have on your health.