Article category: Garden Planning. Published 2026-04-28 by Pocket Gardener Team.
Topics: raised bed soil, soil calculator, garden planning, raised beds, soil volume, bed construction.
Questions answered in this article
How do I calculate how much soil I need for a raised bed?
Multiply internal length by width by depth in metres to get cubic metres. For a 2m x 1m bed at 0.4m deep, you need 0.8 cubic metres. Add 10% for settling. Circular beds use pi x radius squared x depth. Always measure internal dimensions, not external frame edges.
What is the best soil mix for raised vegetable beds?
A practical blend is 40% quality topsoil, 30% compost, 20% coarse sand or fine gravel, and 10% organic matter like leaf mould. For premium results, Mel's Mix uses equal parts vermiculite, peat moss or coir, and blended compost.
Can I fill the bottom of a deep raised bed with cheaper material?
Yes. The bottom third of beds deeper than 45cm can be filled with logs, branches, leaves, and grass clippings that decompose over time. Cover with quality soil mix for planting. This technique saves money and improves long-term soil structure.
Is bulk or bagged soil better for raised beds?
Bulk delivery is cheaper for volumes over half a cubic metre. Bagged mixes are convenient for small beds, balconies, and top-ups but cost two to three times more per litre. Order bulk when possible for larger projects.
How deep should soil be in a raised bed?
30cm is the minimum for most vegetables. Root crops need at least 30cm, while tomatoes, corn, and other deep-rooted crops prefer 45-60cm. Deeper beds drain better and provide more root room, but require more soil and cost more to fill.