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Mount Washington Arboretum · Baltimore, MD

Basil

Thai

Ocimum basilicum

Annual

Care at a glance

☀️ LightFull sun (6–8 hrs)
💧 WaterRegular; keep moist but not waterlogged
📅 Days to maturity60–90
🌀 LifecycleAnnual
🗺 Hardiness zoneAnnual (frost-sensitive)
🌡 Temperature55°F – 90°F
↕ Height12–24"
↔ Spread10–16"
📏 Spacing12" apart

Soil

pH: 6.0–7.0  ·  Rich, moist, well-drained

Nutrients & Fertilizing

Moderate; balanced fertilizer monthly

Baltimore Planting Windows

Based on last frost ~May 1, first frost ~Oct 31 (Zone 7a)
🌱 Direct sow (spring)May 15 – Jun 1
🪴 Transplant out (spring)May 1 – May 15

About this plant

Popular sweet, spicy basil that is essential in Thai cuisine. Very flavorful with a nice licorice taste.

Germination

5-10 days

How to plant

• Sprouts in 6-10 Days • Ideal Temperature: 70-85 Degrees F • Seed Depth: 1/4" • Plant Spacing: 8-12"

Growing tips

Ideal temps are 65-95. Pick off flower spikes in early summer to promote vigorous growth

Harvesting

Start harvesting Thai basil leaves once the plant is 6–8 inches tall, typically 3–4 weeks after planting. Pinch off the top 1–2 inches of stems regularly to encourage bushier growth and delay flowering. Harvest in the morning after dew dries for the best flavor. Regular picking keeps the plant productive throughout the season; if you let it flower heavily, leaf quality declines. For storage, use fresh leaves within a few days, or freeze them in ice cube trays with a little water or oil for longer keeping. Thai basil can also be dried, though it loses some of its distinctive anise-like character when dried compared to fresh use.

Recipes using this plant

Fermented Herb Mix · by Grace McClintock
Another way to use whatever the garden is providing, but also create something that keeps for a long time. This is a fermented fresh herb salad dressing mix made in late summer and fall for use all winter. Stir into vinegar and olive oil for a quick dressing, blend into drained kefir for a creamy dip, or add to soups. Recipe from Monique Trahan via Grace.

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