Although I grow different types of basil in my Virginia garden, last year was the year of Thai basil for me. Thai basil is a variety of sweet basil (Ocimum basilicum) but the flavor is spicier and more pungent — like anise and clove combined. I grew a couple of varieties for the culinary and beverage aspects as well as for landscape value.
Thai basil gets its name from its popularity in Thai cuisine, but it is equally popular in Cambodian, Vietnamese, and Laotian cuisines. Thai basil can withstand prolonged cooking heat so the leaves work well with chicken or beef stir fried dishes. Thai basil also is used in Pad Thai, Vietnamese Pho, spring rolls, curries, and noodle dishes.
Last year, I discovered how to use Thai basil to make a refreshing drink. I combined one cup sugar and one cup water in a small saucepan. I added a cup of loosely packed leaves, which I mashed up against the side of the pot. After bringing to a boil and simmering for 15 minutes, I let the syrup cool, drained off the leaves, and poured the sweet, spicy syrup in a glass jar.
I added a few spoonsful of the syrup to a glass of limeade (made from a frozen concentrate). It was delicious. Immediately the thought popped in my head “Now if I add gin, would that be a Thai basil gimlet?” I could easily see how this syrup could be used in mojitos, gin and tonics, daiquiris, and martinis.
I could also tell that this flavor would work well with citrus. I poured a few spoonsful over sliced oranges and it was delicious. Adding spices such as cloves and cinnamon – maybe even cardamom – would make the flavor even more complex. Another option would be to either add the syrup or mince the Thai basil leaves on mango, pineapple, or papaya.
Because of their pretty flowers, Thai basil is used in vinegars. To make a vinegar, simply fill a glass jar with a 5 percent vinegar such as apple cider or white wine and add the flower heads and foliage. Let sit in a dark place for a few weeks. Drain off the foliage and leave the flower heads. These makes great gifts.
The flower spike can be used in fresh or dried floral arrangements. Basil flowers are made up of a calyx that dries and remains on the stem and the actual small flower inside, which eventually drops off after it has bloomed. This makes basil ideal for dried floral arrangements as well as potpourris.
I also use Thai basil as an annual in the garden bed, just like any other annual. It adds a purple haze, similar to coleus, and tolerates our heat and humidity very well. I don’t pick the leaves, I just let it grow and flower in a mass.
Like other basils, this plant needs full sun and plenty of water in the summer. It is easy to start from seed after the average last frost when nighttime temperatures stay warm. Although we grow it as an annual, it really is a tender perennial that perishes with our fall frosts. It makes a good container plant but can also be grown in the garden bed or a raised bed.
You may see two popular varieties that are more ornamental and larger with a broader shape: Siam Queen and Cardinal. Cardinal has large, dark red flower heads with burgundy red stems and bright green leaves. Siam Queen also has large flower heads that are dark, purple-red with dark leaves. Siam Queen is a 1997 All-American Selections winner. There is also Everleaf Thai Towers which is a columnar plant with delayed flowering. It is perfect for an accent piece in a tall container.
Thai basil is not prone to the downy mildew disease that affects sweet basil. I have never had a pest or disease issue although I have noticed that it is quicker to flower than the other basils. The solution is to have many plants, some for leaves, some for flowers or to purchase one bred to have delayed flowering like the Everleaf series. Unlike the sweet basil which is pinched to prevent flowering, you can either pinch your Thai basil to prevent flowering and harvest the leaves or let the plants flower and use the flowers as a garnish, for flower arrangements, or vinegars.