Designing a Raised Bed Herb Garden
The most functional herb garden groups plants by water and sun needs rather than by culinary category. Mediterranean herbs (rosemary, thyme, oregano, sage, lavender) need excellent drainage and full sun with low water. Kitchen herbs (basil, parsley, cilantro, dill) need more moisture and do well in the same sun but different watering regimen. Aggressive spreaders (mint, lemon balm, tarragon) need containment to prevent them from taking over.
The Containment Problem: Mint and Its Relatives
Mint spreads aggressively by underground runners and will colonize an entire raised bed within two seasons if planted without restraint. The standard solution: plant mint in a pot and sink the pot into the raised bed so the rim sits 1–2 inches above soil level. This blocks the runners without restricting above-ground growth. The same approach works for lemon balm and tarragon.
Which Herbs to Grow Together
Group 1 — Mediterranean (dry, excellent drainage): Rosemary, thyme, sage, oregano, lavender. These share identical watering needs (let soil dry between waterings) and benefit from slightly alkaline, lean soil. Add extra perlite or gravel to their section of the bed. Group 2 — Moist-soil herbs: Basil, parsley, chives, fennel, dill. These need consistent moisture and richer soil. Group 3 — Separate: Cilantro and fennel should not go near tomatoes or peppers (fennel is mildly allelopathic); cilantro bolts quickly and is best in its own section for easy succession planting. Mint: contained as above.
For companion planting principles more broadly, see our guide to companion planting with vegetables.
Harvesting for Maximum Regrowth
The harvesting technique matters as much as the timing. Basil: Pinch off stem tips just above a leaf node; never strip leaves from the main stem. Pinch off any flower stalks immediately — basil becomes bitter and slows leaf production once it flowers. Rosemary and thyme: Cut stem tips back by no more than 1/3 of their length. Cutting into old woody stems produces no regrowth. Parsley: Cut outer stems at the base; inner stems continue growing. Chives: Cut the whole clump to 1–2 inches above soil level; it regrows fully within 3–4 weeks.
Overwintering Perennial Herbs
In zones 5–6: rosemary typically does not survive winters outdoors (it's hardy to zone 7). Pot it up before frost and overwinter indoors in a sunny window. Thyme, sage, oregano, and chives survive zone 5 winters in the ground if mulched. Lavender varies by variety — 'Hidcote' and 'Munstead' are hardier than Spanish lavender. In zones 7+, all Mediterranean herbs overwinter reliably in a raised bed.
FAQ
Which herbs are easiest for beginners?
Chives, mint (contained), parsley, and thyme are the most forgiving. They tolerate irregular watering, resist common pests, and produce reliably over a long season. Basil is more demanding (needs warmth, consistent moisture, and immediate deadheading) but worth growing for its yield and value.
How deep does a raised bed need to be for herbs?
6 inches is the minimum for most herbs. 8–10 inches works better for parsley, fennel, and dill, which develop tap roots. Mint and chives are happy in 6 inches.
Can I grow rosemary in zone 5?
Only in a container — rosemary is hardy to zone 7 outdoors. In zones 5–6, grow it in a pot outdoors in summer, bring inside for winter. Place in the sunniest south-facing window available and water only when soil is dry (overwatering is the most common way to lose indoor rosemary).
Why is my basil turning yellow?
Most commonly: overwatering or cold soil. Basil needs warm soil (above 60°F), consistent moisture but not waterlogging, and high nitrogen. Yellow lower leaves in a well-watered plant often indicate nitrogen deficiency — fertilize with a balanced liquid fertilizer.
When should I harvest herbs for drying?
Harvest in the morning after dew evaporates but before full afternoon heat — this is when essential oil concentration is highest. Harvest before flowering for the best flavor. Dry by hanging in small bunches in a warm, dark, ventilated space for 1–2 weeks.