Choose a bed around the site, crops, reach and watering routine, then compare wood, metal, masonry and fabric frames. UMN Extension suggests a soil mix of roughly one-half to two-thirds topsoil and one-third to one-half plant-based compost, and says a bed reachable from both sides can be up to 5 feet wide. Treat those figures as guidance for planning, then adjust to the material, soil and access you have.
Raised beds let you set the growing area apart from the surrounding ground, but their frame and fill affect cost of upkeep, access and watering. Choose the layout first, then compare materials and soil for that location.
Compare bed styles
| Style | Useful when | Check before choosing |
|---|---|---|
| Wood frame | You want boards that are easy to cut and assemble | Expected service life, board length, treatment label and whether you want a liner along the sides |
| Metal panels or trough | You want a durable, assembled panel system | Panel material and coating, soil acidity guidance, sharp edges and the maker’s assembly instructions |
| Brick or stone | The bed should match a permanent landscape | Wall stability, expense, drainage and whether the material could change soil pH |
| Fabric grow bag | You need a movable, container-style bed | Capacity, support, drainage and more frequent watering |
| Unframed raised ground bed | You want a mound rather than a container | Soil quality below, reach from the path and erosion at the edges |
UMN Extension describes wood, metal, masonry, plastic and fabric as options, with different upkeep and site tradeoffs. Its guidance notes that some bricks can raise soil pH, and that container-style beds dry out faster than ground soil. Check the current material label and product instructions; do not assume all products in a material category share the same treatment or coating.
Size the bed for reach and crops
Set it where plants will get the light they need and where a hose or watering can can reach. For a bed you can reach from one side, UMN Extension suggests keeping the width to about 2.5 feet; with access on both sides, it gives up to 5 feet. These are access guidelines, not required dimensions. Shorter boards can be less likely to warp or break than long runs, and several small beds can make crop rotation easier.
Check the finished height against the people who will use it and the surface below. A bed on pavement behaves more like a container and needs drainage. A bed over garden soil can connect with the ground below, so a bottom barrier is usually unnecessary and may restrict roots. Use a permeable liner when a hard surface makes a bottom necessary.
Plan the soil fill
UMN Extension’s raised-bed guide suggests roughly one-half to two-thirds topsoil with one-third to one-half plant-based compost. It cautions that too much compost can affect water retention and recommends using manure or composted manure sparingly, guided by a soil test. Bagged mixes and delivered topsoil vary, so check their ingredients and quantities before calculating how much to order.
Estimate the fill volume from the bed’s inside length, width and depth. Keep notes on the mix and test the soil when deciding whether to add more compost or fertilizer. For composting inputs and equipment, compare bins and tumblers.
Next steps for a garden
For an earlier start on transplants, compare seed-starting lights and heat mats. If you want crop cover as well as beds, see greenhouse kits and hoop houses. For perennial plantings with different spacing needs, see fruit trees for a small orchard. Browse food garden guides.
Sources
Common questions
What is the best material for a raised bed?
There is no single best frame. Compare how long it should last, whether you can reach all sides, the site surface, maintenance and any material-specific guidance.
How wide should a raised bed be?
Make it narrow enough to reach the center without stepping on the soil. UMN Extension gives up to 2.5 feet for one-sided access and up to 5 feet when both sides are reachable.
Can I fill a raised bed with potting mix?
UMN Extension says potting mixes can dry too quickly for raised beds. Its guide suggests combining topsoil with plant-based compost and using a soil test to guide other inputs.
Does a raised bed need a liner underneath?
Usually not when it sits over garden soil. On a patio or other hard surface, a permeable bottom liner can help retain soil while allowing water to drain.