A standard herb spiral is 5–6 ft in diameter and 3 ft tall at the center. This size fits 20–30 herbs in microclimates from hot/dry at the top to cool/moist at the base. A 4 ft diameter works for small spaces but holds only 10–15 plants.

Small (4 ft diameter): 10–15 herbs, good for patios and small gardens
Standard (5–6 ft): 20–30 herbs, ideal for most home gardens
Large (7–8 ft): 30–50 herbs, provides more growing space and microclimates
Height: 2–4 ft at center, tapers to ground at outer edge
Footprint: a 6 ft spiral takes just 28 sq ft of ground space

How many stones do I need for an herb spiral?

A 6 ft diameter, 3 ft tall herb spiral with 6-inch stones needs approximately 200–400 stones depending on stone size and wall thickness. Flat fieldstone or broken concrete work well. Budget about 1 ton of stone for a standard 6 ft spiral.

6 ft spiral: approximately 200–400 stones, about 1 ton total weight
Use flat stones (4–8" tall) for stable, easy stacking
Fieldstone, flagstone, or broken concrete are common choices
No mortar needed — dry-stack allows drainage and easy adjustments
Reclaimed brick or urbanite (broken concrete) works great and is free

What herbs go where on an herb spiral?

Top (hot/dry): Mediterranean herbs like rosemary, thyme, oregano, and lavender. Middle: sage, cilantro, parsley, and chives. Bottom (cool/moist): mint, lemon balm, and chamomile. The spiral creates microclimates matching each herb's native conditions.

Top (hot, dry, full sun): rosemary, thyme, oregano, lavender, marjoram
Upper middle (warm, well-drained): sage, tarragon, savory, hyssop
Lower middle (moderate moisture): parsley, cilantro, chives, dill
Bottom (cool, moist, partial shade): mint, lemon balm, chamomile, sorrel
North-facing side gets shade — plant shade-tolerant herbs there

How much soil does an herb spiral need?

A 6 ft diameter, 3 ft tall herb spiral needs about 10–15 cu ft of soil mix (roughly 5–7 bags of potting soil). Use a 50/50 mix of compost and garden soil. Add gravel at the base for drainage, especially in clay soil areas.

6 ft spiral: 10–15 cu ft of soil mix (about 0.4–0.6 cubic yards)
Soil mix: 50% compost + 50% garden soil for most herbs
Add sand or perlite for Mediterranean herbs at the top (better drainage)
Richer compost at the bottom for moisture-loving herbs
Base layer: 3–4 inches of gravel or rubble for drainage foundation

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Last Updated: Jun 17, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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