Raised Garden Bed Guide for Herbs
A raised garden bed is one of the best ways to grow culinary herbs and spices at home. By elevating the growing area above ground level and filling it with a custom soil blend, you gain control over drainage, soil quality, and growing conditions that in-ground beds often cannot match. Raised beds warm up earlier in spring, drain more freely, and are easier on your back and knees. For herbs — many of which demand excellent drainage — a raised bed is close to ideal.
Choosing a Size and Location
A 4-by-8-foot bed is the most common size and works well for an herb garden. Keep the width at 4 feet or less so you can reach the center from either side without stepping into the bed (compacting the soil). Height of 10–12 inches is sufficient for most herbs; go deeper (18–24 inches) if you are growing turmeric, ginger, or other plants with deep root systems.
Place the bed in a spot that gets at least 6 hours of direct sun. South-facing is ideal. Ensure the site has reasonably level ground. If your yard slopes, you may need to level the area or build one side of the frame higher.
Materials
Common choices for the frame:
- Untreated cedar or redwood — naturally rot-resistant, attractive, and lasts 10–15 years. The most popular choice.
- Pine or fir (untreated) — cheaper but will rot within 3–5 years. Acceptable for a budget build.
- Concrete blocks or stone — permanent, inexpensive, and require no carpentry. Blocks can be stacked without mortar.
- Galvanized steel or corrugated metal — modern look, very durable, heats up in sun (good for early spring warmth, but monitor soil moisture).
Avoid railroad ties and pressure-treated lumber manufactured before 2004, as they may contain harmful chemicals. Modern pressure-treated wood (ACQ-treated) is generally considered safe for vegetable and herb gardens, according to Oregon State University Extension, but many gardeners prefer to avoid it and use cedar instead.
Filling the Bed
Do not use garden soil alone — it is too heavy and compacts in a raised bed. A good herb bed fill recipe:
- 50% high-quality topsoil or screened garden soil
- 30% compost (aged, finished compost — not fresh manure)
- 20% coarse perlite, pumice, or coarse sand for drainage
For Mediterranean herbs like rosemary, sage, and oregano, increase the perlite/sand to 30% for sharper drainage. For moisture-loving tropicals like turmeric and ginger, increase the compost to 40%. See Soil Mix for Herbs for detailed recipes.
Layout for an Herb Garden Bed
When planning which herbs to put where, consider mature plant size, growth habit, and water needs:
- Back/north side: Tall plants — rosemary, dill, lemongrass
- Middle: Medium plants — basil, sage, cilantro, parsley
- Front/edges: Low-growing plants — chives, oregano, Thai chili peppers
Group plants with similar water needs together. Drought-tolerant Mediterranean herbs (rosemary, sage, oregano) should be on one end, and thirstier plants (basil, cilantro, parsley) on the other. See Herb Garden Layout Plans and Companion Planting with Herbs for more ideas.
Maintenance
Top-dress the bed with an inch of compost each spring. The soil level will settle over time as organic matter breaks down — replenish as needed. Mulch between plants with straw, shredded leaves, or broken-down straw bale material to retain moisture and suppress weeds.