How To Fill A 24-Inch Raised Garden Bed With The Right Soil

A 24-inch raised bed can look manageable until you start pricing the soil. If you are figuring out how to fill a raised garden bed, measure its usable space and decide what you will grow before buying bags or arranging a delivery.

For an open-bottom metal bed on suitable garden ground, a consistent raised-bed mix is a straightforward choice. Leave space below the rim for watering, and keep enough growing mix for your crops. If you use lower fill, calculate the remaining planting depth before deciding how much soil to buy.

Table of Contents

• Check The Bed Before Buying Soil
• Calculate How Much Soil You Need
• Choose A Growing Mix For The Site
• Decide What Goes At The Bottom
• Fill The Bed And Check For Settling
• Match The Fill Plan To A GARVEE Bed
• Common Questions About Filling Tall Beds

Check The Bed Before Buying Soil

First, check whether the bed has an open bottom or a supported planting box. Open-bottom raised garden beds sit on the ground; their roots may continue into suitable native soil. A planter on legs holds its growing mix above ground.

Assemble the frame, including any specified braces, before filling it. Measure the clear inside length and width, then mark your intended soil level below the rim. Use those measurements for the order instead of assuming the advertised outside dimensions are an exact soil capacity.

Also check the ground beneath an open-bottom bed. Poor drainage does not disappear when you add tall walls, and a bed on concrete cannot give roots access to deeper native soil. Resolve the site and drainage plan before the soil arrives.

Calculate How Much Soil You Need

For a rectangular bed, multiply inside length by inside width by intended fill depth, all in feet. Divide cubic feet by 27 to get cubic yards, the unit commonly used for bulk deliveries.

Soil volume in cubic feet = length in feet × width in feet × fill depth in inches ÷ 12.

The examples below assume rectangular footprints and a 22-inch fill depth, leaving 2 inches below a 24-inch rim. That headspace is a planning example, not a required fill line or a manufacturer-rated capacity. No bottom filler is included.

Bag counts are rounded up from the unrounded volume and assume each bag contains 2 cubic feet. For two beds, 59 bags cover the combined calculation; buying a separately rounded order of 30 bags for each bed means 60. These estimates exclude settling, spills, and differences between nominal and inside measurements.

For the 8 × 4 ft example, the arithmetic is 8 × 4 × 22 ÷ 12 = 58.67 cubic feet. If your measured inside width is smaller, recalculate before ordering. Buying a little extra for top-ups can be useful, but ask the supplier about expected settling instead of assuming one allowance fits every mix.

Compare the delivered cost per cubic foot. Divide a bag price by its labeled volume; for bulk soil, include delivery and any minimum order. Also consider how you will move the material from the drop-off point to the bed.

Choose A Growing Mix For The Site

Open-Bottom Beds On Garden Ground

Choose a raised-bed mix or a supplier's blend of topsoil and finished compost. Check the ingredients and ask for soil-test information.

For compacted or clay-heavy sites, University of Maryland Extension describes blends of one part compost to two parts topsoil, or equal parts of each. Follow local soil-test advice when choosing amendments.

Beds On Hard Surfaces And Planters With Legs

For beds over concrete, Maryland Extension recommends a compost-and-soilless growing mix. Its guidance calls for at least 8 inches of depth for leafy greens, beans, and cucumbers, and 12–24 inches for peppers, tomatoes, and squash. Check drainage and the usable depth left after any lower fill.

For a planter on legs, use container-suitable media and check the manufacturer's weight limit. University of Minnesota Extension cautions that bagged garden soil and topsoil are too heavy for pots or elevated garden boxes. Follow the planter instructions and keep its drainage openings clear.

For example, the GARVEE cedar planter with legs is listed at 31 inches overall, with a 13.7-inch-deep planting box. The 24-inch fill calculations above do not apply to it.

Decide What Goes At The Bottom

An open bottom does not automatically need an added liner or filler. Start with the condition of the ground, the crops, and any barrier the manufacturer specifies.

Cardboard For Existing Grass

Plain cardboard can help smother turf during site preparation. Remove tape and staples; it is temporary weed suppression rather than substantive filler or a drainage base.

Logs And Branches As Lower Fill

Woody fill is often associated with hugelkultur, a method that combines wood, plant debris, and soil. It reduces the initial amount of purchased growing mix, but also changes the root space and how the bed settles over time.

A Washington State University Extension review describes settling as woody material decomposes and questions broad claims made for the method. For a first bed, filling the usable depth with a consistent growing mix makes the soil order easier to calculate. Choose woody fill only as a deliberate growing method, with crop-appropriate soil depth and future top-ups in mind.

How Lower Fill Changes The Soil Order

Suppose a plan suited to your crops and site uses 6 inches of lower fill in the rectangular 8 × 4 ft example. With a total fill depth of 22 inches, that leaves 16 inches of growing mix. Calculate each portion separately:

The upper growing mix would take about 22 two-cubic-foot bags, compared with 30 bags for the full-mix example. You still need to supply the lower 16 cubic feet. This is a volume illustration, not a standard layering recipe; use it only after confirming the material, rooting depth, and drainage are suitable.

Gravel And Miscellaneous Debris

Do not add a gravel layer to a supported planter just to improve drainage. Illinois Extension explains that water can collect in the growing medium above gravel. Use suitable media and functioning drainage openings instead.

Keep treated wood, painted scraps, plastic packaging, and unidentified construction debris out of a food-growing bed. Cheap space-filling material is a poor bargain if you cannot establish what it contains or how it will affect the growing area.

Fill The Bed And Check For Settling

1. Finish the site and frame. Clear the planting area, set the bed level, and secure the panels and required supports. Arrange access for watering and for carrying soil before the bed becomes heavy.
2. Add the prepared growing mix evenly. Spread it across the footprint and into the corners as you work. Follow the mix supplier's directions for moistening dry material; avoid dumping the entire load against one side panel.
3. Water gently and inspect. Allow water to drain, then check the surface level. Rake the mix into place rather than stamping it down, and keep walking or kneeling outside the bed.
4. Top up before planting. Add matching mix where settling leaves low areas while preserving the intended space below the rim. Recheck the level after the first few waterings, especially if you used decomposable lower fill.

Set aside some of the same mix for adjustments instead of using every bag immediately. Once planted, check moisture in the growing medium itself; a dark-looking surface does not tell you how wet the full root zone is.

Match The Fill Plan To A GARVEE Bed

These open-bottom metal options have 24-inch walls. Choose the footprint and number of beds you can both fill and maintain, then use your actual inside measurements for the final order.

Common Questions About Filling Tall Beds

Does A 24-Inch Bed Need Soil All The Way To The Rim

Leave space for watering below the rim. The useful growing depth depends on the plants, the surface beneath the bed, and any lower fill you choose. A 24-inch wall does not mean every crop needs exactly 24 inches of purchased soil.

Can I Use Only Topsoil

Topsoil varies, so check its texture and suitability. For open-bottom beds, blend it as needed with finished compost. A supported planter needs container-suitable media, and the filled weight must stay within its load limit.

How Much Soil Does An 8 By 4 Foot Bed Need

At an assumed 22-inch fill depth, a rectangular 8 × 4 ft bed takes about 58.7 cubic feet, or 2.17 cubic yards. Measure inside dimensions and adjust the depth before treating that as your shopping quantity.

Can I Reduce The Soil Bill Without Adding Logs

Compare suitable bulk blends with bagged mixes, including delivery. If you have not bought the bed yet, a smaller footprint or one bed instead of two reduces the amount you need to fill. Price the complete order, including any lower fill and likely top-ups, before choosing.

To decide how to fill a raised garden bed, work from your measured inside dimensions and the depth of suitable growing mix. If you are still choosing a frame, compare the GARVEE 6 × 3 ft bed and 8 × 4 ft bed, then make a soil shopping list for the size you choose.

More to read

How To Build A Raised Garden Bed: A Comprehensive Guide

Metal Raised Garden Beds Vs. Wooden Raised Garden Beds: Which One Should You Choose?