How Deep Should Raised Garden Beds Be? (2024)

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.

32" Extra Tall 9 In 1 Modular Metal Raised Garden Bed Kit

$329.95 $279.95

Our extra tall 32" height eliminates bending and strain on your back when you tend to your garden, as well as creates plenty of space for healthy roots.…

How Deep Should Raised Garden Beds Be? (2)

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How Deep Should Raised Garden Beds Be? (2024)

FAQs

How Deep Should Raised Garden Beds Be? ›

The minimum required depth depends on the plant. But on average, a raised garden bed should accommodate about 20 inches of soil for the roots of flowers and vegetables.

What is the best depth for raised beds? ›

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.

How deep should a raised bed be for tomatoes? ›

Tomatoes should ideally be grown in a raised bed that's at least 15 to 18 inches deep. Many of my clients in Houston are successfully growing tomatoes in 12-inch deep raised garden beds, but their plants tend to be a little stunted compared to plants in deeper beds.

Is 1 foot deep enough for a raised garden bed? ›

A 1-foot raised bed is more than enough to accommodate a salad garden box plan. Carrots, radishes and peppers thrive with 12 inches or more. Medium-rooting vegetables like kale, cucumbers, and zucchini love at least 18 inches.

Is 10 inches deep enough for raised bed? ›

However, the bottom must be strong enough to both hold the weight of the soil when it is wet and still allow water to drain. A few other considerations to keep in mind: Most garden crops need at least 10 inches of soil to thrive. If the raised bed height is lower than this, till the existing soil below the raised bed.

How deep should soil be for raised vegetable beds? ›

The Best Height for Raised Beds

Keep in mind that beds 18 inches deep or more will have better drainage than shorter beds. While most plants don't need anything deeper than 18 inches, I prefer beds that are two feet deep (24 inches). The extra height is mostly just for the ease and convenience of the gardener.

What do you put in the bottom of a raised garden bed? ›

Soil is the foundation of your garden, and you want it to be healthy so you can set your plants up for success! We recommend buying high-quality, nutrient-rich soil in bulk. Or, you can make a soil mix with equal parts topsoil, organic materials (leaves, composted manure, ground bark), and coarse sand.

How deep does a raised bed need to be for cucumbers? ›

Eighteen inches is the minimum height needed for plants like tomatoes, cucumbers, squash, zucchini, and kale—plants that have a bigger root base and need more nutrients and space to spread out.

How many bags of soil do I need for a 4x8 raised bed? ›

For a 4x8-foot raised bed with a 6” height, using Mel's Mix: about 5 cubic feet each of compost, peat moss, and vermiculite is needed. It usually takes about two to three bags of purchased fertile mix (1.5 cubic feet each) to cover the bed surface to a depth of 2 inches.

How many tomato plants can I plant in a 4x4 raised bed? ›

A 4ft. x 4ft. raised garden bed gives you 16 square feet of growing space (more if you add some trellises for vertical space). That means you can grow around 10 to 11 indeterminate, or vining, tomato plants in one raised bed—if you really love cherry tomatoes, that is.

How deep does a raised bed need to be for peppers? ›

Soil Depth Requirements for Common Garden Vegetables
Shallow Rooting 12" - 18"Medium Rooting 18" - 24"
LettucePeppers
Onions, Leeks, ChivesRutabagas
PotatoesSquash, summer
RadishesTurnips
13 more rows

How deep should a raised bed be for potatoes? ›

Fingerling potatoes are small, prolific, and tasty, and are therefore especially appropriate for raised beds. Setting up Raised Beds: Raised beds should be at least 12 inches deep and filled to about six inches with a good planter mix and lots of compost.

What kind of soil should I use for raised garden bed? ›

Topsoil should be dark and crumbly with an earthy smell. Do not purchase soil that is very high in sand or clay, foul-smelling, or has grayish mottling or a chalky, sticky, or rough texture. Some sellers have a mix of topsoil and compost which can make an excellent growing media for raised beds.

What is the cheapest way to make raised beds? ›

Raised beds made of cinder blocks or concrete blocks

Cinder blocks and concrete blocks are very inexpensive (typically $2 to $3 a piece at home improvement centers), and they make it really easy to build the outline of a raised garden bed.

How deep are most vegetable roots? ›

Shallow-rooted crops root to a depth of 12 to 18 inches. Moderate-rooted crops develop roots to a depth of 18 to 24 inches. Deep-rooted crops develop a root system to a depth of 24 or more inches.

What vegetables can grow in 8 inches of soil? ›

Shallow-rooted vegetables root to a depth of 6 to 12 inches, making them ideal for container gardening or gardens with limited soil depth. Some of the best shallow-rooted vegetables include: Swiss Chard, Chives, Endive, Celery, Lettuce, Onions (bunch), Onions (dry), Spinach, Fennel, Shallot, and Radish.

Is 11 inches deep enough for raised bed? ›

The most popular height for raised beds is 11″. (This is the height of two standard “2 x 6″ boards, which actually measure 1.5″ x 5.5”.) This height provides sufficient drainage for most crops. For best results, there should be another 12″ or more of good soil below the bed.

What is the best size for a raised vegetable bed? ›

The optimum size for raised garden beds is around four feet wide and eight feet long. This size provides a good balance between planting space and ease of access. However, the size of your raised garden bed will ultimately depend on your available space, gardening needs, and budget.

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