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Thai Sweet Large Leaf Basil is a tender annual herb that brings the aromatic essence of Southeast Asian cuisine right to your garden. This open-pollinated cultivar of Ocimum basilicum produces generous, soft leaves with a distinctive anise-like flavor and pungent aroma that defines authentic Thai cooking. The plants reach 18 to 24 inches tall and are ready to harvest in 70 to 79 days, thriving in full sun and spacing of 12 inches apart. While typically grown as an annual, it can persist as a perennial in warm tropical climates, rewarding gardeners with tender foliage that only improves with heat and time.
Full Sun
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9-11
24in H x ?in W
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This variety yields surprisingly large, tender leaves that taste faintly of anise and release an intoxicating pungent aroma when bruised or brushed. The plants thrive in hot, dry conditions where other basils struggle, and they can adapt to growing in the ground, containers, raised beds, or greenhouses with equal enthusiasm. The relatively quick path to first harvest (around 70 days) combined with the plant's ability to keep producing through the heat of summer makes it a reliable choice for anyone seeking authentic Thai flavors from their own garden.
The tender leaves are harvested fresh for Thai curries, particularly green and red curry pastes where their anise-forward flavor contributes depth and complexity. Fresh sprigs are added to soups like tom yum and tom kha gai just before serving, providing a bright, aromatic finish. The leaves work beautifully as a fresh garnish or wrapped alongside cooked proteins and herbs in lettuce wraps, a beloved Thai preparation. Because the foliage becomes more pungent and flavorful in heat, this basil shines during summer months when you're most likely craving Thai food.
No timeline data available yet for this variety.
Start seeds indoors 35 to 40 days before your last frost date in a warm location around 70°F. Sow seeds shallowly, press gently into moist seed-starting mix, and maintain consistent warmth and humidity until germination. Transplant seedlings when they have developed true leaves and the weather has warmed.
Harden off seedlings by gradually exposing them to outdoor conditions over 7 to 10 days. Transplant outdoors only after the last frost date has passed and soil temperatures have warmed; basil is extremely frost-sensitive. Space plants 12 inches apart in rows spaced 18 inches apart. Bury the stem up to the lowest true leaves to encourage a stronger root system.
Direct sow seeds outdoors after the last frost date when soil has warmed. Sow seeds shallowly into prepared soil and keep the area consistently moist until germination. Thin seedlings to 12 inches apart once they've developed true leaves.
Begin harvesting once plants reach 6 to 8 inches tall, which typically occurs around 70 to 79 days from planting. Pinch or cut leaves from the top of the stem just above a leaf node, working your way down the plant to encourage branching. Harvest frequently and consistently to promote continued growth and leaf production throughout the season. The tender young leaves offer the most delicate flavor, though the plant remains productive through summer heat. You can harvest individual leaves or cut entire stems, depending on your immediate needs.
Pinch off the top 1/4 inch of growing stems regularly to encourage bushier, more branched growth and delay flowering. Remove flower heads as they form to redirect the plant's energy into leaf production rather than seed development. Regular harvesting through pinching and leaf removal serves as pruning; the more you harvest, the more actively the plant branches and produces new foliage.
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“Thai Sweet Large Leaf Basil descends from the diverse basil cultivars traditionally cultivated across Southeast Asia, particularly in Thailand where the herb holds deep culinary roots. This particular strain has been preserved as an open-pollinated, heirloom variety, maintaining the genetic diversity and traits that have made it valued for generations. The catalog designation of 'heirloom' indicates it represents a heritage line passed down through seed saving, likely by Thai and Thai-diaspora gardeners who recognized its superior performance in hot climates and its authentic flavor profile that cannot be replicated by more modern, commercially developed basil varieties.”