A 36-inch raised garden bed offers generous root space and a comfortable working height, but it also requires a significant amount of material.

Filling the entire bed with bagged potting soil can be unnecessarily expensive. Filling it entirely with compost, logs, or fresh yard waste can create a different set of problems, including excessive settling, uneven moisture, nutrient imbalances, and unstable planting depths.

The best filling method depends on:

• What you plan to grow
• Whether the bed sits over soil or concrete
• How quickly you want to plant
• Whether the crops are annual or perennial
• Which clean materials are locally available
• How much future settling you are willing to manage

This guide explains nine practical ways to fill a 36-inch raised garden bed while preserving a healthy upper growing zone.

Quick Guide: What Goes in Each Layer?

A practical 36-inch raised bed may be divided into three general zones.

These depths are flexible. Deep-rooted vegetables and permanent crops should receive more stable soil and less decomposable material.

1. Calculate the Volume Before Buying Anything

The first step is to calculate how much material the bed holds.

Use this formula:

Length × width × height = cubic feet

Because 36 inches equals three feet, a bed measuring 8 feet long and 4 feet wide holds:

8 × 4 × 3 = 96 cubic feet

Divide cubic feet by 27 to convert the amount into cubic yards:

96 ÷ 27 = approximately 3.56 cubic yards

Common 36-Inch Raised Bed Volumes

Measure the actual interior dimensions rather than relying only on the advertised exterior size. Panels, braces, curved ends, and corners may slightly change the total volume.

Bulk soil is usually more economical for a large bed than individual bags. The University of Minnesota notes that high-quality topsoil purchased by the cubic yard is generally less expensive than buying the equivalent volume in bags. Its raised bed garden guide also provides useful soil-mixing guidance.

2. Match the Growing Layer to the Plants

Not every crop needs 36 inches of premium growing soil.

Shallow-rooted vegetables such as lettuce, radishes, spinach, green onions, and many herbs can grow in the upper 8 to 12 inches. Tomatoes, parsnips, long carrots, asparagus, rhubarb, okra, and other vigorous crops benefit from a deeper, stable root zone.

Use these general targets when planning the upper layer:

These are practical planning ranges rather than strict biological limits. Roots may travel farther when soil, water, and oxygen conditions are favorable.

If you plan to grow deep-rooted vegetables, reserve at least the upper 18 to 24 inches for a stable soil-based mixture. If you plan to grow permanent asparagus or rhubarb, consider filling most of the bed with quality soil because extensive settling may disturb the crowns.

3. Prepare the Ground Under the Bed

The correct base preparation depends on where the raised bed will be installed.

When Installing Over Lawn

Mow the grass as short as possible. Place overlapping plain cardboard over the area to suppress grass and weeds.

Remove:

• Plastic tape
• Shipping labels
• Staples
• Glossy coatings
• Waxed sections
• Heavily colored packaging

Wet the cardboard after positioning it so it conforms to the ground.

Cardboard should be treated as a temporary weed-suppression layer, not as the main filling material. It will break down over time.

Oregon State University describes cardboard as one component of sheet mulching and lasagna gardening, particularly when combined with leaves, straw, compostable material, and a soil layer.

When Installing Over Native Soil

If the underlying soil is healthy and uncontaminated, loosen the surface with a garden fork before adding the raised-bed mix. This can reduce the abrupt boundary between the native ground and the new soil.

Oregon State University recommends loosening existing soil before adding a soil or compost mixture in its guide to improving garden soil with organic matter.

When Installing Over Concrete

Confirm that the location can support the final weight. Provide an unobstructed drainage path so excess water does not collect inside the bed.

Do not allow fine soil to wash directly into drains. A suitable permeable separation layer may help retain soil while allowing water to escape.

4. Use Clean, Stable Soil in the Lower Layer

For the most stable result, fill the lower section with clean mineral soil, screened topsoil, or an economical bulk soil mixture.

This method is especially useful for:

• Permanent crops
• Beds installed over concrete
• Deep-rooted vegetables
• Gardeners who want minimal settling
• Beds that will not be rebuilt frequently

Suitable lower-layer materials may include:

• Clean native topsoil moved from another part of the property
• Screened, uncontaminated fill soil
• Economical sandy loam
• A basic soil blend from a landscape supplier
• Older raised-bed soil from another garden area

Do not use soil from land that may contain herbicide residue, construction waste, lead, oil, road salt, or other contaminants.

Avoid using pure clay as the bottom layer. Dense clay can slow drainage and create a sharp barrier below the looser growing soil.

5. Use Woody Materials Only When Settling Is Acceptable

Logs, branches, wood chips, and bark can reduce the amount of purchased soil needed. They also decompose over time, which means the bed will gradually settle.

Suitable materials may include:

• Untreated branches
• Small logs from healthy trees
• Aged arborist wood chips
• Untreated wood scraps without paint or glue
• Partially decomposed woody material

Avoid:

• Pressure-treated lumber
• Painted or stained wood
• Plywood
• Particleboard
• MDF
• Diseased plant material
• Black walnut wood around sensitive plants
• Wood contaminated by chemicals

Place large pieces near the bottom and use smaller materials to fill the gaps. Cover the woody layer with several inches of soil before adding the final growing mix.

Oregon State University discusses using carbon-based materials such as wood chips, limbs, or straw in the bottom of deep raised beds, followed by a loamy soil and compost mixture. Its article also warns against excessive compost use: Too much of a good thing?.

When Not to Use a Large Woody Layer

Avoid a thick log layer when planting:

• Asparagus
• Rhubarb
• Permanent artichokes
• Long-lived herbs
• Fruit shrubs
• Other plants that should remain at a stable depth

As wood decomposes, the planting surface may drop. Annual vegetable beds are easier to top up than beds containing established crowns.

6. Fill Part of the Bed With Leaves and Yard Materials

Autumn leaves, clean straw, aged grass clippings, and garden debris can provide an inexpensive lower filling layer.

Suitable materials include:

• Shredded autumn leaves
• Leaf mold
• Clean straw
• Finished or partially finished compost
• Pesticide-free garden debris
• Aged grass clippings applied in thin layers
• Small amounts of untreated plant stalks

Mix different materials rather than compressing one thick layer of wet grass or leaves. Dense layers can mat together, restrict airflow, and create unpleasant anaerobic conditions.

Avoid adding:

• Diseased plants
• Weeds with mature seeds
• Invasive plant roots
• Meat or dairy products
• Pet waste
• Fresh manure
• Plants treated with persistent herbicides
• Large quantities of kitchen scraps

Fresh organic material may shrink substantially as it decomposes. Expect to add more soil or compost to the surface during the following season.

This method works best when the bed can be filled several months before planting. If you need to plant immediately, use a deeper finished-soil layer above the unfinished material.

7. Build a Balanced Topsoil and Compost Growing Mix

The upper layer is the most important part of the bed. It should support roots, retain water, drain excess moisture, and remain structurally stable.

A practical starting mixture is:

• 50–70% quality topsoil
• 20–35% finished plant-based compost
• 10–20% additional structural material when needed

Possible structural components include:

• Aged pine fines
• Leaf mold
• Coarse horticultural material
• Additional loamy soil

The exact mixture should be adjusted to the characteristics of the available topsoil. Sandy soil may need more moisture-retaining organic matter, while heavy soil may need a lighter, better-aerated structure.

The University of Minnesota suggests approximately one-half to two-thirds topsoil and one-third to one-half plant-based compost for raised beds. Oregon State University gives a more conservative recommendation of up to approximately 25% compost by volume in its guide to using compost in gardens and raised beds.

The difference illustrates an important point: compost quality, soil texture, climate, salinity, and crop requirements vary. Begin with a soil-based blend and avoid assuming that more compost is always better.

8. Water the Layers as You Fill

Dry soil can appear to fill the bed but settle several inches after the first heavy rain.

Add material in stages:

1. Add approximately 6 to 8 inches of material.
2. Spread it evenly.
3. Water lightly.
4. Allow the material to settle.
5. Fill obvious gaps.
6. Add the next layer.
7. Repeat until reaching the final level.

Do not heavily compact the upper growing zone by walking on it or repeatedly pressing it down. The goal is to remove large air pockets without destroying the pore space roots need.

Stop the final soil level slightly below the top edge of the bed. Leaving approximately 2 to 3 inches of space helps contain mulch and irrigation water.

After watering, wait a day or two and check the level again before planting.

9. Finish With Mulch and Plan for Annual Top-Ups

Apply approximately 2 to 3 inches of suitable mulch after planting.

Mulching can:

• Reduce water evaporation
• Moderate soil temperature
• Limit weed germination
• Reduce soil splashing
• Protect the soil surface
• Add organic matter as natural mulch decomposes

Suitable vegetable garden mulches include:

• Clean straw
• Shredded leaves
• Leaf mold
• Untreated grass clippings applied thinly
• Fine bark around permanent plants

Keep mulch slightly away from young stems and plant crowns.

Organic mulch naturally decomposes. The University of Minnesota explains that materials such as shredded bark,

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9 Smart Ways to Fill a 36-Inch Raised Garden Bed

A 36-inch raised garden bed can make gardening more comfortable, improve growing conditions over poor ground, and provide generous root space for vegetables and perennial crops.

However, a three-foot-tall bed also requires a surprising amount of material. Filling the entire structure with bagged garden soil can become expensive, while using too much compost or unstable organic material may cause settling, nutrient problems, and uneven planting surfaces.

The best filling method depends on three questions:

1. What will you grow?
2. What surface is underneath the bed?
3. How much settling are you willing to manage?

This guide explains nine practical ways to fill a 36-inch raised garden bed while maintaining healthy soil, reliable drainage, and enough depth for plant roots.

How Much Soil Does a 36-Inch Raised Bed Need?

Before ordering soil, calculate the internal volume of the bed.

Use this formula:

Length × Width × Height = Cubic Feet

Because 36 inches equals 3 feet, an 8-foot-long, 4-foot-wide bed holds:

8 × 4 × 3 = 96 cubic feet

To convert cubic feet into cubic yards, divide by 27:

96 ÷ 27 = 3.56 cubic yards

Common 36-Inch Raised Bed Volumes

Measure the inside of the bed rather than relying only on its advertised exterior dimensions.

If you use large pieces of wood, leaves, or another lower filler, the amount of purchased soil will decrease. However, organic filler will break down and lose volume over time, so plan for future top-ups.

Recommended Soil Depth by Crop

Not every plant needs three feet of premium growing soil.

The remaining lower section can sometimes be filled with less expensive material. The correct choice depends on whether the bed will hold annual vegetables or permanent crops.

1. Use a Full-Depth Soil Blend for Perennial Crops

Filling the entire bed with a stable soil blend is the most expensive option, but it is also the most reliable for asparagus, rhubarb, artichokes, berries, dwarf fruit plants, and other long-term crops.

Perennial plants remain in place for years. A deep layer of branches, logs, straw, or leaves underneath them may decompose and settle, potentially changing the planting depth around established crowns.

A full-depth blend can include:

• Screened loam or topsoil
• Finished plant-based compost
• A suitable mineral component when needed
• A tested raised-bed soil mixture

Avoid using pure compost. Plants need a stable soil structure that contains mineral particles as well as organic matter.

The University of Minnesota recommends approximately one-half to two-thirds topsoil combined with one-third to one-half plant-based compost for many raised beds. Its raised bed garden guide provides additional soil and accessibility recommendations.

Best for: Asparagus, rhubarb and other permanent plantings
Main advantage: Minimal long-term settling
Main disadvantage: Highest initial cost

2. Use Clean, Screened Soil in the Lower Section

One of the simplest ways to reduce costs is to fill the lower 12 to 18 inches with clean, screened soil and reserve a higher-quality blend for the upper root zone.

The lower soil does not need to contain as much compost as the planting layer, but it should still be:

• Free from construction debris
• Free from herbicide residues
• Free from invasive weed roots
• Free from excessive clay
• Able to drain without becoming waterlogged

Do not accept unknown soil simply because it is free. Soil removed from construction sites may contain concrete fragments, contaminants, subsoil clay, or persistent weed seeds.

Ask the supplier where the soil came from and whether it has been screened. When possible, examine the material before delivery.

Best for: Deep annual vegetable beds
Main advantage: Stable and less expensive than premium soil
Main disadvantage: Quality varies considerably between suppliers

3. Order a Bulk Raised-Bed Mix

For large 36-inch beds, bulk soil is usually more practical than individual bags.

Landscape suppliers may offer products described as:

• Raised-bed mix
• Garden blend
• Planting mix
• Three-way mix
• Topsoil-compost blend

Names are not standardized. Two suppliers may sell very different materials under the same label, so ask for the ingredients and proportions.

A suitable blend should feel loose and crumbly while still containing enough mineral soil to hold plants upright and retain water. Avoid mixtures composed almost entirely of fine compost or ground wood.

Oregon State University recommends using readily available bulk materials because framed raised beds require substantial quantities of soil. Its raised bed gardening guide discusses native soil, bulk soil mixes, compost, leaf mold, and well-composted manure.

Best for: Filling several beds at once
Main advantage: Lower cost per cubic yard
Main disadvantage: Delivery fees and inconsistent product quality

4. Add Wood Chips or Small Branches to the Bottom

Wood chips, small branches, and untreated woody garden material can occupy part of the lower section of a tall bed.

This method works best when:

• The bed contains annual vegetables.
• The gardener accepts gradual settling.
• At least 18 inches of quality soil will cover the material.
• The wood is untreated and free from disease.
• Additional soil can be added in future years.

Use a mixture of different particle sizes instead of stacking large logs with wide air gaps. Pack smaller chips around branches and water the layer to help it settle.

Avoid:

• Painted wood
• Pressure-treated scraps of unknown origin
• Plywood
• Particleboard
• Railroad ties
• Diseased tree material
• Black walnut wood around sensitive plants
• Wood exposed to industrial chemicals

Woody materials break down slowly and reduce initial soil costs, but they are not permanent structural fill. As they decompose, the soil surface will sink.

Oregon State University includes wood chips and limbs among possible carbon-based materials for the bottom of tall beds, followed by a loamy soil-and-compost mix. See its discussion of compost use in raised beds.

Best for: Annual vegetable beds that can be topped up
Main advantage: Uses inexpensive local material
Main disadvantage: Predictable settling over time

5. Use Leaves and Straw for a Faster-Decomposing Layer

Dry leaves, straw, and chopped garden residue can be used in the lower part of a 36-inch bed. These materials are lightweight and readily available, but they decompose faster than branches.

Compress the material before adding soil. Loose leaves may initially appear to fill a large space but can collapse substantially after watering.

A practical lower layer might contain:

• Shredded autumn leaves
• Clean straw
• Finished or partially finished leaf mold
• Chopped non-diseased plant residue
• Small amounts of untreated grass clippings mixed with dry material

Do not place a thick, wet mass of fresh grass clippings in the bed. It may become compacted, slimy, and oxygen deficient.

Keep at least 18 inches of growing soil above rapidly decomposing material when planting tomatoes, root vegetables, or other large crops.

Best for: Seasonal annual gardens
Main advantage: Often free and easy to source
Main disadvantage: Faster settling than woody filler

6. Place Cardboard at the Bottom for Weed Suppression

Cardboard can help suppress grass and weeds beneath an open-bottom raised bed, but it should be treated as a base layer rather than a major filler.

Remove:

• Plastic tape
• Shipping labels
• Staples
• Glossy coatings
• Waxed sections

Overlap plain brown cardboard so grass cannot immediately grow through gaps. Wet it before adding the next layer so it stays in place.

Cardboard gradually breaks down, allowing roots, water, earthworms, and other soil organisms to move between the bed and the ground below.

If the bed sits over aggressive perennial weeds such as bindweed, Bermuda grass, or nutsedge, cardboard alone may not provide permanent control.

Oregon State University describes cardboard-based sheet mulching in its guide to sheet mulching and lasagna gardening.

Best for: Beds installed over lawn or annual weeds
Main advantage: Reduces early weed pressure
Main disadvantage: Does not fill meaningful bed volume

7. Reserve the Top 18 to 24 Inches for Growing Soil

Regardless of the lower filler, the upper portion determines how well most vegetables grow.

For a 36-inch bed intended for tomatoes, carrots, parsnips, potatoes, squash, or sweet potatoes, reserve approximately 18 to 24 inches for stable growing soil.

A general blend may include:

• 50–65% screened topsoil or loam
• 25–35% finished plant-based compost
• 10–20% additional mineral or structural material when necessary

These percentages are starting points rather than universal formulas. Existing soil texture, compost maturity, climate, crop choice, and local material quality should influence the final mixture.

Do not automatically add sand to heavy clay. Small amounts of sand mixed into clay can create a dense, concrete-like texture. Use an appropriate loam or professionally prepared soil blend instead.

Utah State University recommends compost-enriched topsoil or an appropriate soilless growing mix for raised beds. Its raised bed gardening guide also emphasizes adequate sunlight and improved rooting depth.

Best for: Nearly every vegetable bed
Main advantage: Concentrates the best material around roots
Main disadvantage: Still requires a substantial amount of soil

8. Limit the Amount of Compost

Compost is valuable, but more is not always better.

Filling a tall bed entirely with compost can lead to:

• Excessive phosphorus or potassium
• High soluble salt levels
• Rapid settling
• Poor structural support
• Nutrient imbalance
• Excessive moisture retention
• Plant stress or weak germination

Manure-based compost should be treated more like a fertilizer than a neutral soil substitute. It may contain considerably more nutrients and salts than plant-based compost.

Oregon State University recommends limiting compost to around 25% by volume in some raised-bed filling situations. Review its guide on how to use compost before ordering large quantities.

The University of Minnesota also notes that high compost salinity can inhibit germination and stress plants, especially in beds where salts are not flushed by regular rainfall. Its guide to interpreting compost reports explains pH and soluble salt measurements.

When possible, obtain a soil or compost analysis rather than judging quality by color alone.

Best for: Preventing nutrient and salt problems
Main advantage: Creates more balanced long-term soil
Main disadvantage: Requires sourcing quality topsoil instead of relying only on compost

9. Water the Layers, Allow Settling and Top Up

Do not fill a 36-inch bed to the top with dry material and immediately assume the final level is correct.

Instead:

1. Add the lower material in manageable layers.
2. Water each layer lightly.
3. Compress large air pockets without creating severe compaction.
4. Add the growing mix.
5. Water again.
6. Wait several days when possible.
7. Add more soil where the surface has dropped.
8. Leave space for mulch below the rim.

A finished bed should generally have one to three inches of space between the soil surface and the top edge. This helps keep mulch, irrigation water, and loose soil inside the bed.

Beds containing branches, leaves, or straw may need additional soil every year. Beds filled primarily with mineral soil and finished compost should settle less, although some reduction in volume is still normal.

Best for: Every filling method
Main advantage: Prevents uneven planting surfaces
Main disadvantage: Adds time before planting

Three Recommended Filling Plans

Plan A: Best for Deep-Rooted Vegetables

Use this plan for tomatoes, carrots, parsnips, okra, corn, sweet potatoes, and winter squash.

This plan balances cost savings with adequate root depth.

Plan B: Best for Perennial Vegetables

Use this plan for asparagus, rhubarb, artichokes, and other long-term crops.

Avoid thick layers of rapidly decomposing material directly underneath permanent crowns.

Plan C: Lowest-Cost Annual Garden

Use this plan only when annual settling is acceptable.

This plan costs less initially but will require regular top-ups.

What Should Not Go Into a 36-Inch Raised Bed?

Avoid using the bed as a disposal container. Do not add materials that may contaminate soil, interfere with drainage, or injure roots.

Rocks and Gravel as a Drainage Layer

A thick gravel layer does not automatically improve drainage. Water movement depends on soil texture, drainage openings, the installation surface, and how different materials interact.

Rocks also add considerable weight without feeding plants or improving soil volume.

Construction Debris

Do not use drywall, concrete, insulation, roofing material, painted lumber, treated scraps, or demolition waste.

Plastic Bottles and Foam Packaging

These materials do not create healthy soil and may collapse, shift, interfere with water movement, or introduce plastic fragments.

Fresh Manure

Fresh manure can contain high salt levels, excessive nitrogen, weed seeds, and pathogens. Use properly composted products and follow local food-gardening recommendations.

Diseased Plants

Diseased tomato vines, infected roots, and pest-infested crop residue should not be buried directly beneath the next garden.

Meat, Dairy and Oily Food Waste

These materials may attract rodents and other animals. Compost appropriate kitchen scraps in a managed composting system before adding the finished compost to the bed.

Pure Potting Mix

Lightweight container mixes can be useful ingredients, but filling a large outdoor bed entirely with potting mix may be expensive and may not provide enough weight or long-term mineral structure.

Filling a Bed Over Different Surfaces

Over Healthy Garden Soil

Remove persistent weeds and loosen compacted soil beneath the bed with a garden fork. This helps roots and water move between the raised bed and native ground.

Over Lawn

Mow the grass low and cover it with overlapping plain cardboard. Avoid placing a waterproof barrier beneath an open-bottom bed.

Over Compacted Clay

Loosen the surface when possible and make sure excess water has somewhere to escape. A raised bed improves the root zone, but it cannot correct a site where water remains trapped around the entire structure.

Over Concrete

Confirm that the surface can support the fully saturated weight. Provide drainage openings and a route for runoff so water does not collect around the bed.

A 36-inch bed over concrete needs enough stable soil to support the planned crops because roots cannot continue into the ground below.

Over Gravel

Place a durable, permeable separation layer if necessary to prevent soil from washing into large gravel gaps. Do not block drainage.

How Heavy Is a Filled 36-Inch Raised Bed?

Soil weight varies according to texture, organic matter, and moisture. A large bed may weigh several thousand pounds after watering.

For example, an 8-by-4-by-3-foot bed holds approximately 96 cubic feet of material. Even a relatively light mixture creates substantial pressure against the sides.

Make sure the bed is:

• Positioned on a stable surface
• Level before filling
• Properly assembled
• Equipped with required cross braces
• Accessible to delivery equipment
• Located correctly before soil is added

Moving a filled bed is usually impractical.

8 Common Filling Mistakes

1. Buying Soil Before Calculating Volume

This often results in either an expensive surplus or an unfinished bed.

2. Filling the Entire Bed With Compost

Compost is an amendment, not a complete substitute for stable soil.

3. Using Unknown Free Fill

Contaminated soil, persistent herbicides, weed roots, and construction waste can create long-term problems.

4. Leaving Large Air Gaps

Branches and coarse materials should be packed carefully so the upper soil does not collapse into open spaces.

5. Using Too Little Growing Soil

A thin top layer may be sufficient for lettuce but not for tomatoes, carrots, or perennial vegetables.

6. Ignoring Future Settling

Organic lower layers will decompose. Keep extra soil or compost available for top-ups.

7. Blocking Drainage

Plastic sheets and other impermeable materials may trap water inside the bed.

8. Filling Before Checking Structural Bracing

A tall bed must be level, secure, and reinforced before thousands of pounds of soil are added.

Frequently Asked Questions

What is the cheapest way to fill a 36-inch raised bed?

Use clean bulk soil rather than individual bags, and reserve the highest-quality mix for the top 18 to 24 inches. Untreated woody material or leaves can reduce costs in annual beds when future settling is acceptable.

Do I need to fill all 36 inches with soil?

No. Many vegetables grow primarily within the upper 12 to 24 inches. However, perennial crops and beds installed over concrete benefit from a deeper layer of stable soil.

How much compost should I use?

The appropriate amount depends on the compost and existing soil. A mixture containing approximately 25% to 35% finished plant-based compost is a reasonable starting point for many beds, but soil testing and local extension guidance are preferable.

Can I fill the bottom with logs?

Untreated woody material can be used in the lower portion of an annual bed. Expect decomposition and settling, and keep a substantial layer of stable growing soil above it.

Can I use tree stumps?

Large stumps create major air gaps and decompose unevenly. Smaller branches and chips are easier to pack and produce a more predictable layer.

Can I use only topsoil?

Topsoil can be too dense or low in organic matter when used alone. Mixing appropriate topsoil with finished compost generally produces better structure.

Should I put landscape fabric inside the bed?

Landscape fabric is usually unnecessary between soil layers. A permeable layer may be useful over gravel, but impermeable plastic should not block drainage.

How far below the top should the soil be?

Leave approximately one to three inches below the rim so irrigation water, mulch, and loose soil remain inside the bed.

How often will I need to add more soil?

Beds filled with stable soil may need a small annual top-up. Beds containing branches, straw, or large amounts of leaves may settle more noticeably during the first few years.

Can I use the same filling method for a 12-inch bed?

A 12-inch bed has limited depth, so nearly all of it should normally be filled with quality growing soil. Lower filler layers are more appropriate for taller 24-inch raised beds and 36-inch models.

Final Thoughts

The best way to fill a 36-inch raised garden bed is to work backward from the crops you plan to grow.

Annual vegetables can be grown over clean soil, wood chips, branches, leaves, or other appropriate lower materials, provided they receive a generous upper layer of stable growing soil. Perennial crops should be planted in a more permanent mixture that will not dramatically settle beneath their crowns.

Calculate the volume before ordering, verify every material source, limit compost to a sensible proportion, protect drainage, and expect some natural settling.

With a strong frame and the right filling plan, a 36-inch tall metal raised garden bed can provide deep soil, comfortable access, and productive growing space for many seasons.