What's the best soil mix for raised beds?
Soil quality is the single most important factor in raised bed productivity. Unlike in-ground gardens where you amend existing soil, raised beds require filling with an imported growing medium. The ideal mix must balance water retention, drainage, aeration, and nutrient availability. Popular approaches range from the well-known Mel's Mix (equal parts compost, vermiculite, and peat moss) to bulk topsoil-and-compost blends, to cost-saving layered methods like hugelkultur. Soil depth, compost quality, and the ratio of organic to mineral components all significantly affect plant performance. Over-amending with compost is a common mistake that can cause nutrient imbalance and poor drainage. A good raised bed mix should feel loose and friable, hold moisture without becoming waterlogged, and provide a diverse nutrient profile from multiple compost sources.
- Soil depth guidelines by crop type5
Matching soil depth to crop root requirements prevents wasted soil volume and ensures adequate growing space. Shallow-rooted crops (6-8 inches minimum): lettuce, spinach, radishes, green onions, most herbs, strawberries. Medium-rooted crops (10-12 inches minimum): beans, peppers, cucumbers,…
📌 best practice2/7/2026, 9:53:51 PM
🛠️ Tape measure, soil mix sufficient for target depth plus 10-15% overfill
- Biochar as a long-term soil amendment4
Biochar is charcoal produced by burning organic material (wood, crop residues) at high temperature with limited oxygen (pyrolysis). Its microscopic honeycomb structure provides permanent habitat for beneficial soil microbes, dramatically increasing the soil's biological activity and…
📌 best practice2/7/2026, 9:53:44 PM
🛠️ Horticultural-grade biochar (not BBQ charcoal), compost tea or liquid fertilizer for charging, bucket for soaking, garden fork for mixing into soil
- Coconut coir as peat moss alternative4
Coconut coir (the fibrous husk of coconuts) is an increasingly popular sustainable replacement for peat moss in raised bed mixes. Unlike peat, which takes thousands of years to form in boreal bogs and releases stored carbon when harvested, coir is a renewable agricultural byproduct. Coir has a…
📌 best practice2/7/2026, 9:53:33 PM
🛠️ Compressed coconut coir bricks, large container for hydrating, warm water, garden fork for breaking apart
- Worm castings as a premium compost component5
Worm castings (vermicompost) are the richest, most biologically active form of compost available. They contain 5x more nitrogen, 7x more phosphorus, and 11x more potassium than average garden soil, plus a dense population of beneficial microorganisms. Use worm castings as 15-25% of your total soil…
📌 best practice2/7/2026, 9:53:24 PM
🛠️ Worm castings (purchased or from home worm bin), home worm bin (optional: 10-gallon tote, red wiggler worms, bedding material, kitchen scraps)
- Native soil amendment approach3
If you have decent native soil (loamy, not heavy clay or pure sand), you can amend it in place rather than importing an entirely new mix. Remove the top 6-8 inches of native soil, screen out rocks and roots, then mix it 50/50 with quality compost. Add perlite (10% by volume) if the native soil has…
📌 DIY2/7/2026, 9:53:16 PM
🛠️ Shovel, soil screen or hardware cloth frame, compost, perlite, wheelbarrow, soil test kit or extension service submission
- The 'From Scratch' custom blend (30/40/20/10 recipe)4
For gardeners who want full control over their soil composition, a custom blend of 30% sifted topsoil, 40% composted materials, 20% aeration/drainage amendments, and 10% specialty additions creates a highly productive growing medium. The topsoil provides mineral content, structure, and weight. The…
📌 DIY2/7/2026, 9:53:09 PM
🛠️ Screened topsoil, multiple compost sources, perlite or pumice, worm castings, kelp meal, greensand, alfalfa meal (optional), mixing tarp or wheelbarrow, pH test kit, garden fork
- Commercial raised bed mix (bagged)3
Pre-mixed bagged raised bed soil from brands like FoxFarm Ocean Forest, Miracle-Gro Raised Bed Soil, Coast of Maine Castine Blend, or Kellogg Raised Bed Mix offers convenience and consistency. These products are formulated specifically for container and raised bed growing, with balanced drainage,…
📌 commercial2/7/2026, 9:52:57 PM
🛠️ Bagged raised bed soil mix, wheelbarrow (optional), garden fork for mixing/fluffing
- Hugelkultur base layer for deep beds4
Hugelkultur (German for 'hill culture') fills the bottom half of deep raised beds (18+ inches) with logs, branches, and woody debris, topped with 12+ inches of quality soil mix. As the wood decomposes over several years, it acts as a carbon sponge that retains moisture, slowly releases nutrients,…
📌 DIY2/7/2026, 9:52:49 PM
🛠️ Logs, branches, and twigs (untreated hardwood), cardboard, leaves/straw, grass clippings or manure, finished soil/compost for top layer, garden hose for watering layers
- Topsoil-and-compost bulk blend (60/40 or 50/50)4
The most cost-effective way to fill raised beds is ordering bulk screened topsoil mixed with compost, typically delivered by the cubic yard from landscape supply companies. A 60% topsoil / 40% compost blend (by volume) provides a balanced growing medium at a fraction of bagged mix costs. Bulk…
📌 DIY2/7/2026, 9:52:40 PM
🛠️ Bulk screened topsoil, bulk compost, wheelbarrow, garden fork or shovel, perlite or coarse sand (optional amendment)
- Mel's Mix (1:1:1 compost, vermiculite, peat moss/coir)5
Mel's Mix, from Mel Bartholomew's Square Foot Gardening method, is the most widely recommended raised bed soil recipe: equal parts (by volume) blended compost, coarse vermiculite, and peat moss (or coconut coir as a sustainable substitute). This creates an exceptionally light, well-draining medium…
📌 best practice2/7/2026, 9:52:32 PM
🛠️ Compost from multiple sources, coarse vermiculite, peat moss or coconut coir, wheelbarrow or mixing tarp, garden fork, measuring containers