Siam Queen

Family: Lamiaceae Herb

Fragrant as a warm green breeze, Siam Queen leaf basil unfurls tender, lettuce-leaf foliage with a bright, clean sweetness and a cool minty lift that lingers on the palate.

The leaves are impressively soft and ruffled—delicate yet substantial—ideal for spooning into fresh, aromatic dishes and for turning into vibrant pesto-style sauces. Grow it for a steady, quick harvest rhythm around day 45, when plants are lush enough to keep your table perfumed all season long.

Light: Full SunMaturity: 45 DaysHabit: Upright

Planting schedules and alerts are optimized for Columbus (Zone 6b).

Crop Dates

Milestone	Date
Start Indoors	Apr 11th
Last Frost	Apr 25th
Transplant / Sow Outdoors	Jun 6th
Harvest Begins	Jul 21st
Harvest Ends	Oct 16th

Crop Details

Trait	Value
Days to Maturity	45
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	60
Min Night Temp (°F)	50
Harden Off (days)	10

Culinary Notes

Chef's Note

Siam Queen is a lettuce-leaf basil built for tenderness—its ruffled leaves stay plush in raw applications and don’t turn bitter when pulsed for pesto. The cool minty lift makes it especially electric with citrus and seafood, where you want aroma to ride the spoon, not drown it.

Best Uses

raw spoon-in herb for salads and yogurt bowls (won’t fight the dressing)
quick chiffonade over citrusy seafood and grilled chicken
lettuce-leaf basil pesto (blend fast, keep it green and silky)
fresh finish for noodle broths—add at the last second so it stays aromatic

Flavor Profile

bright, clean sweetness cool minty lift on the finish fragrant warm-green aroma soft, ruffled leaf tenderness

Kitchen Pairings

lime garlic olive oil lemon zest parmesan salmon

Frequently Asked Questions

What pest or disease problem commonly affects Ocimum basilicum (Siam Queen), and how can I control it?

Watch for downy mildew and leaf spot, which show up as pale/yellow patches or dark spots that expand quickly in humid weather. Remove affected leaves early, improve airflow by thinning plants, and water at the soil line (not overhead) to keep foliage dry; if it’s spreading, use an approved copper-based fungicide according to label directions. Also check weekly for basil pests like aphids and spider mites and rinse them off with a strong jet of water, repeating as needed.

How often should I water Siam Queen basil (Ocimum basilicum) during the main growing phase?

During the main growth period, keep the soil consistently moist but not waterlogged—aim for the top 1 inch to dry slightly between waterings. In full sun, that often means watering every 1–3 days depending on heat and pot vs. ground conditions. Water deeply enough to wet the root zone, and stop if you see prolonged soggy soil or yellowing leaves.

How do I tell when Siam Queen basil (Ocimum basilicum) is ready to harvest?

Harvest when plants reach about 6–8 inches tall and have multiple sets of leaves, usually around 45 days after sowing for Siam Queen. For best flavor and regrowth, pinch or cut just above a pair of leaves (not the stem tip alone), taking no more than about one-third of the plant at a time. Start harvesting before flower buds open, because once flowering begins leaves become more bitter.