How to Build a Raised Garden Bed - Elevated and Raised Garden Beds
Raised garden beds have many benefits when compared with growing plants directly in the garden soil. Raised garden beds come in various forms and sizes and can be adjusted to any small garden.
Updated: August 19, 2021.
Benefits of Raised Garden Beds
Main benefits of using raised beds and growing plants in them:
- growing season in raised garden beds is longer - soil in raised beds dries and warms faster in late winter and early spring, enabling gardeners to extend the growing season.
Also, many raised bed kits come with an option of a protective transparent cover, practically being small greenhouses.
Such covers protect from late spring and early autumn cold nights, which can damage sensitive plants. Also, transparent cover can be easily replaced with protective nets - protection from pests like birds, but let the bees and other good insects do their job.
- garden is generally cleaner when raised beds are used - walkways between raised beds can be covered with gravel, concrete tiles, and similar materials that drain water well and don't allow weeds to grow.
Some gardeners prefer grass between raised beds - such surfaces require regular mowing and during periods of prolonged rain, they can turn to mud pools. Since raised beds are rarely more than 4 feet (1.2 m) wide, their soil surface can be maintained more easily, especially if covered with mulch or hydroton pebbles.
- reduce labor and back strain - since raised and elevated garden beds are moved off the floor level, bending over is not required. Some gardeners make raised beds up to a waistline high, drastically reducing strain on the back and legs.
However, such raised beds require plenty of soil, and to avoid that some gardeners use elevated beds - garden beds in the form of pots and containers fully above the soil level. Raised beds are easily covered with a layer of mulch (1-2 inches, 2.5 - 5 cm).
Such layers reduce weeds and decrease moisture loss. When strawberries are grown in raised beds, mulch prevents strawberries from touching wet soil and prevents them from rotting.
- help deal with local bad soil - regardless if you have bad soil in the garden (sandy soil, heavy soil, etc) or you want to create special conditions for a certain plant, raised beds can be filled with the soil as required.
- raised beds can be very decorative - they can be built using various materials and can be built in various shapes and sizes. The taller the raised beds, the less back strain. Also, some pests can't reach plants growing in an elevated position.
Of course, there are other benefits of raised beds that are not right away obvious, but in the long run, can make a significant difference.
Size, Shape, and Material for Garden Raised Beds
Raised beds should be tailored according to the individual needs and preferences of every gardener.
However, they should be tall enough to decrease physical labor. The width should be kept up to 4-5 feet (1.2 - 1.5 m) but not more than that - this way entire surface is easily reachable for everyday work.
Most of the raised beds are made in rectangular form, but they can be rounded, too, especially if they are in the form of larger pots or bags.
Materials should be long-lasting (10+ years), should NOT rot, should be chemically free, insects, and sun resistant. These include:
- concrete blocks and bricks - concrete, concrete blocks, bricks, and similar materials are used for making raised beds that will last almost forever.
Such materials require certain DIY knowledge about masonry, but possible sizes and shapes are endless - if somebody wants to raise beds with certain curvature due to various reasons, these materials are often the best choice. Note that after building such beds, concrete needs a certain time to 'settle down' - it contains calcium oxide that reacts with moisture and creates calcium hydroxide that dissolves in water, entering the soil, where it can change the pH of the soil.
To avoid that, when the concrete raised bed is finished, let it be for few weeks - during these weeks, water the concrete occasionally. If you don't have that much time, fill the raised bed with the soil, slightly more acidic than required or at the exact pH as required, but check from time to time the pH near the concrete or mortar.
- various plastics parts and kits - plastic pots, plastic containers, or plastic raised bed kits are made from non-toxic plastic, resistant to rot, moisture, insects, pests, sun. Such parts must have a declaration that they are made for herbs, fruits, and vegetables, otherwise, they can be used for flowers only.
- wooden boards - since in raised beds we plan on growing food, wooden boards should not be treated chemically. In order to last longer, cedar and similar types of wood are used due to their resistance to insects and rot.
Plastic and wooden raised bed kits are often the best option for home gardeners since they require little DIY experience (just be sure to read the manual), can be found in various sizes and shapes, are relatively cheap, and can be filled with the soil and planted right away.
Gardeners with DIY habits can make raised beds rather simply using wooden planks - draw a plan of your garden with desired raised bed on the piece of paper, measuring everything as it is.
Draw a plan of your raised bed with exact measures, checking everything at least twice. Cut the wood to desired lengths and piece everything together.
If you are not sure about this, ask for the help of professionals or order a kit. Most basic raised beds require 4 planks and 8-12 screws for wood - however, even that is sometimes enough to make some damage or injure somebody!
Soil for the Raised Garden Beds
Soil can be found really cheap, however, such soil usually contains plenty of sand - good for drainage, but such soil doesn't retain moisture and nutrients well.
So, first thing first - if you are positioning raised bed on the grass, be sure to remove the grass with the top 4-5 inches (10-13 cm) of soil. This will prevent weeds problems in the future, especially if the raised bed is a foot or less high.
If your soil has drainage issues, after removing the grass and topsoil, position the raised bed and fill in 2-4 inches (5-10 cm) of gravel. This layer of gravel will help drain away excess water from the soil in the raised bed.
Soil for the Plants with the Shallow Root System
If the raised bed is around one foot (30cm) high, fill in good garden soil mixed with aged manure, compost, humus, and NPK fertilizer with gradual release of nutrients. The exact NPK formulation depends on planned plants.
If your raised bed is at least 20 inches (50 cm) high, fill it first with aged manure (5-6 inches, 12-15 cm) and rest with good garden soil with aged manure, compost, humus, and NPK fertilizer with gradual release of nutrients.
If your raised bed is around one yard (or one meter) high, feel free to fill it first (one foot, 30 cm) with wooden chips, sawdust, and straw, add a layer of aged manure (another foot, 30 cm), and finally a layer (16 inches, 40 cm) of garden soil mixed with aged manure, compost, humus, and NPK fertilizer.
As organic matter decompose, it warms the raised bed and feeds the plants with nutrients. Also, as it decomposes, it loses volume and sets down - it is necessary to add some soil every year, at least in the first few years.
Soil for the Plants with the Deep Root System
If the depth of the root system of planned berries exceeds the height of raised beds, the entire volume of the raised bed must be filled with good garden soil mixed with aged manure, compost, humus, and NPK fertilizer. Such soil retains moisture and nutrients well and drains excess water easily.
Note that the higher the raised bed, the more soil setting may occur, requiring some soil to be added every year. Hence, if you plan on growing perennial berries in the raised beds, be sure to firmly press the layers in the raised bed and water it several times. Even then, expect some setting to occur.
Berries that benefit most from growing in raised beds are those that require plenty of manual labor - strawberries, for example, must be regularly pruned, strawberry fruit must be elevated from moist soil and picked on a daily basis, runners must be removed as they grow (if large harvest is the goal), etc. Perennial berries that require different pH and type of soil, will also benefit greatly from growing in raised beds.
Examples of Commercial Raised Beds
Here are several examples of raised beds that are available commercially. All Amazon links open in the new window, so feel free to check them out and read more reviews and recommendations.
This is an ordinary plastic pot that has a color and a textured finish like natural clay.
It is 22 inches (56 cm) in diameter and excellent for individual roses, currants, blackberries, and similar berries.
Many people don't consider larger planters as raised beds, but in a container like this, for example, one can plant a rose (for growing roses or roses hips), with enough room for 8-10 strawberries planted near the edge of the container - strawberry fruits should be grown hanging over the edge, thus fully avoiding contact with the soil.
Garden raised bed made from cedar wood - 100% chemical-free.
Dimensions are 4'x8'x10.5" (122x244x27 cm) - IMHO, this raised garden bed has perfect width, while the length is not so important for easy maintenance. Height is 10.5" (~27 cm) - not a very high raised bed, but stacking 2 kits makes 21" (~53cm) high raised bed.
One kit requires around 28 cubic feet (around 230 liters) of compact soil.
Elevated garden bed - ideal for strawberries and similar plants.
Set is made of 100% western red cedar, can be assembled very quickly even without tools.
It requires around 5 cubic feet of soil (around 140 liters).
Very simple raised garden bed - circular raised bed made out of fabric.
It is 50 inches (127 cm) wide and 12 inches (30.5 cm) tall. Due to the height, to avoid issues with weeds, remove topsoil from its permanent position, before filling with the soil.
Again, very simple solution - in the center of the raised bed, there is enough room for, for example, 3-5 tomatoes and on the edge, there is enough room for 20-25 strawberries in a single row.
Of course, when choosing the plants, the only limit is one's imagination ...
Available in packs of 1 or 3, with 3 being more cost-effective, this set offers 4x4 feet (1.22 x 1.22 m) of planting area. It is a stackable design, with a maximum height of 18 inches (around 46 cm).
Parts are made of UV-Protected High-Density Polyethylene (HDPE) - a very resistant material that will not rot, crack or peel off.
Tiered raised garden beds - it can be assembled in tiers or as three individual raised garden beds 4 feet (1.2 m) long, 7 inches (18 cm) high with various widths.
It requires one cubic yard (~0.75 cubic meters) of soil. When assembled and filled with the soil, it is very heavy, and to move it, one would have to remove the soil and take the tiers apart.
The kit is made from 100% chemical-free naturally rot and insect-resistant North American cedar. Very decorative kit.
This raised garden bed is very similar to the Lifetime 60069 raised garden bed, except it acts like a small greenhouse - this model has a protective enclosure in the form of a clear vinyl plastic tent for the early start of the plants.
Ideal for protecting young plants from late spring and early autumn frost. Also, it provides protection from pests like birds and similar.
If you like DIY activities, replace the vinyl tent with a protective net during summer - a net with proper mesh size will protect berries from birds, but will let bees pollinate the flowers.
The kit has 4x4 feet (around 1.2x1.2 m), a stackable design, made from UV-protected high-density polyethylene.
There are many other raised garden bed products on the market today that offer various options to home gardeners. They can be rather cheap and put to use in no time.
Also, remember that the simplest solutions are often the best solutions.