How Deep Should a Raised Garden Bed Be? (2024)

How Deep Should a Raised Garden Bed Be? (1)

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  • Jeremy Wicker
  • May 23, 2022

When planning a raised garden it can be hard to know where to start. There are many factors that go into creating the perfect garden bed place to grow the perfect yield. In this article we will help you determine the best height for a successful raised garden bed.

Some questions to ask when deciding how deep your raised should be:

What kind of plants do I want to grow?

Different plants grow roots to different depths, and some require more vertical space than others. When planning your raised garden, be sure to think about access to sunlight, and the growth heights of your chosen plants.

Where will the raised beds be, and what will they be resting on?

The surface underneath your raised beds affects what depth is best. Generally, if the soil in your bed will be able to exchange moisture with the ground soil underneath, you can get away with a shallower bed. Depth is especially important if your raised bed is resting on concrete or another surface that restricts water flow.

How can the beds be the most accessible?

A deeper bed will have a taller in-fill of soil, and the plants will rest higher off the ground, which means less bending and stooping while tending the garden. Widely spaced rows of 2-foot raised beds with aisles on the sides can be maintained from a seated position, and are perfect for a wheelchair-friendly garden plan.

Let’s break down each of these questions to help you plan the perfect raised garden.

Determining Garden Bed Depth by Plant Type

When planning your raised garden bed depth, the root system is the main piece to keep in mind. Deep-rooting vegetables usually aren’t suitable for raised beds because of the amount of the space they require in all directions–perhaps most importantly, down into the soil. If you are hoping to grow, say, a crop of corn, that may not be your best bet. Luckily, there are plenty of perfect candidates.

Herbs like basil, cilantro, and other low leafy greens like lettuce will grow and grow with just 6 inches of soil. 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. A 2-foot bed is ideal for these types of vegetables, as well as fruits that grow on bushes like blueberries, strawberries, and raspberries.

Where to Place Your Raised Garden Bed

A raised bed does not need to be very deep to be effective, but the surface underneath your garden bed affects which depth is right.

In general, eight inches is a good minimum depth for raised garden beds. If there are issues with drainage, or the plants in the box are sensitive to excess moisture around their roots, additional depth can help by allowing water to seep naturally.

If it is possible for the soil in the raised bed to sit on a liner on top of natural ground soil, the plants in your raised bed can take care of a larger share of their water upkeep for you. When it rains, water will naturally seem into the deeper ground soil. When it is hot or dry, evaporation and plant root systems will pull water back toward the surface. The raised bed soil can thereby retain a healthy amount of moisture without drowning during wetter weather. A 1-foot or 2-foot bed will work well with ground soil drainage.

If the beds will be sitting on top ofconcrete or another surfacethat blocks natural water flow, preventing natural banking and ground drainage, installing adeeper bedcan go a long way toward improving drainage. Lining the bottom of the bed with gravel or a porous growing medium underneath the fertile soil will help balance the water content and prevent soil loss.

Making Accessible Garden Beds

The 2-foot raised beds are the perfect height for gardening from a seat or wheelchair without uncomfortable bending. An open plan with a 2-foot raised bed, or widely spaced rows of them, can form the foundation of a social gathering space for people in independent and assisted living, or become a part of a functioning andaccessible community garden plan.

The Bottom Line: 1-foot vs. 2-foot

The best height for a raised bed depends on your vision for where it will be and what will be in it. A beautiful flower box or tasty herb garden is perfect for 1-foot raised Durable GreedBed.

For more wiggle room for plant roots, some eye-popping vertical flavor in your outdoor space, and better drainage options, a 2-foot raised bed can’t be beat. A little more fertile soil can’t hurt, and a little less bending in the garden certainly won’t. If deeper rooting plants, or wheelchair accessibility are key, a 2-foot depth is a must.

Why Durable GreenBed?

Made with only 85% mineralized wood and 15% cement, Durable GreenBed (based on theFaswall® green building system)is among the most environmentally-friendly and healthy garden building materials available.

Most building materials have serious disadvantages: wood rots and needs to be replaced, treated wood requires care and safe handling; metal often has sharp edges and undersides, and can rust; plastic warps and doesn’t breathe.Durable GreenBed’s patentedwood-cement composite panel materialis easy to install, won’t rot, and is made of 100% recycled material, meaning you can spend more of your gardening time on the plants.

Save Money with a Personalized Discount!

Custom discounts are available on qualifying orders of $4,000 or more. Save money by ordering multiple Durable GreenBed raised garden bed kits. Elevate your garden with a personalized discount crafted just for you.

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How Deep Should a Raised Garden Bed Be? (2024)


How Deep Should a Raised Garden Bed 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 a raised garden bed? ›

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.

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.

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 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.

Should I put rocks in the bottom of my raised garden bed? ›

A: You should avoid putting rocks in the bottom of your garden bed. A common myth is that this will improve drainage. Instead, this can actually increase water saturation levels as well as allow gravel to mix in with your soil, which can prove very difficult to remove later on.

Can a raised bed be too high? ›

As long as it's easy for you to work in it, a raised garden bed can't be too tall, with one proviso: a taller bed is often a deeper bed, and the deeper the bed, the more soil it will hold, and the more pressure there will be on the sides of the bed.

Do tomatoes grow better in pots or in the ground? ›

In general, determinate tomatoes tend to do better in pots, so look for those. It's also possible to grow indeterminate tomatoes in containers, of course, as long as you provide enough support and soil volume.

Which vegetables need deep soil? ›

Pumpkins, winter squash, and watermelons have deep roots that go down 24 to 36 inches or more. Tomatoes, artichokes, okra, and sweet potatoes also have deep roots.

Why put cardboard in raised beds? ›

It acts as a physical barrier to block out pernicious weeds. Usually, 2 – 3 layers of cardboard will suffice, though you may want layers in more weed-prone areas. The damp environment created by the cardboard is conducive to earthworms and other beneficial soil microorganisms.

Should I put landscape fabric under raised bed? ›

Landscape fabric is beneficial for raised garden beds, here are just a few of the many reasons why you should use landscape fabric for raised bed gardening: Prevents soil erosion in a raised bed: As a liner, landscape fabric lets water drain away from the soil while leaving the soil intact.

What is the best filler for the bottom of a raised bed? ›

Plant Waste or Compost

We have a huge pile in the back of our property where we burn leaves, large pieces of wood that we don't want to split, twigs, etc. It's really good to layer all of that stuff in your raised beds as it will break down even more. There were, of course, ashes from burning which will also be good.

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 high should you fill a raised bed with soil? ›

Most were about 18 to 24 “ deep. The depth of the bed can vary, but 6 inches of soil should be the minimum. Most garden plants need at least 6 to 12 inches for their roots, so 12 inches is ideal.

How big is too big for a raised garden bed? ›

The maximum width you would want for a raised bed is about four feet wide, and that would only be for beds that you're able to access from all four sides. Anything beyond four and a half to five feet typically makes plants in the middle of the bed too difficult to reach (unless you have very long arms).

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.

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

Soil Depth Requirements for Common Garden Vegetables
Shallow Rooting 12" - 18"Medium Rooting 18" - 24"Deep Rooting 24" - 36"+
Brussel sproutsBeans, snapBeans, lima
13 more rows

How deep do raised beds need to be for potatoes? ›

Garden beds at least 10-12 inches deep are best for growing potatoes. Otherwise, there won't be enough soil depth for a good crop to develop without the tubers being exposed to sunlight. Sunlight exposure turns potato tubers green.

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