Purple basil is a striking natural variety of green basil. Unlike Thai basil or cinnamon basil, it does not so much stand out by a different taste as by the color of its leaves. With its vibrant foliage, purple basil is a unique addition to any herb garden.
The best way to use purple basil in the kitchen is as a garnish for dishes, rather than processing it for pesto or cooking with it, as the color is the most distinct when the leaves are fresh.
What Is Purple Basil?
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Purple variations of Ocimum basilicum range in color from light red to deep purple. The varieties of purple basil offered by nurseries and seed companies today resulted from extensive breeding of purple basil varieties over many years.
Purple basil tends to crossbreed and despite plant breeders’ best efforts, the desirable genetic traits of basil, namely the leaf color, are often unstable and get lost over time. Be prepared to see some variation in the plants, even in those from the same seed packet.
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| Common Name | Purple basil, red basil |
| Botanical Name | Ocimum basilicum var. purpurascens |
| Family | Lamiaceae |
| Plant Type | Annual, herb |
| Size | 12-24 in. tall, 12-20 in. wide |
| Soil Type | Full sun |
| Soil pH | Moist but well-drained |
| Hardiness Zones | 10–11 (USDA) |
| Native Area | Africa, Asia |
8 Varieties of Purple Basil
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Purple basils vary in height, leaf color and shape, and intensity of aroma. Some types are open-pollinated, which means that you can collect the seeds, and others are hybrids (marked as F1 in seed catalogs). The seeds from those plants are not worth saving because they won’t produce plants that are true to the parent.
Varieties of purple basil include:
- ‘Dark Opal’ (12-18 inches tall) is a popular cultivar that has been around for a long time—it was an All-American Selection (AAS) winner in 1962. It has violet-purple leaves with a hint of licorice. The flowers are pink. In university trials, it has shown resistance to downy mildew.
- ‘Purple Ruffles’ (18-24 inches tall) stands out by its large, glossy, dark purple leaves that are ruffled and fringed. This is the second purple basil that became an All-America Selection winner though it does not have the same assertive anise fragrance as ‘Dark Opal’. The flowers are light lavender with a dark fuchsia throat.
- ‘Red Rubin’ (18-20 in. tall) is a newer, improved version of ‘Dark Opal’ with more uniformly colored leaves. The burgundy-red leaves have a traditional sweet basil flavor and aroma. The flowers are a beautiful lavender-purple color.
- ‘Amethyst’ (16-20 inches tall) is the darkest purple basil variety available with almost black stems and foliage. The leaves are turned downwards and have an intense basil flavor. The flowers are purple. It is also available as the cultivar ‘Amethyst Improved’.
- ‘Prospera Red’ (18-24 in. tall) features large (3-inch), gently cupped dark purple leaves similar to ‘Amethyst’ with a flavor of Genovese basil. The plant has an upright growth habit. It is a hybrid with resistance to downy mildew and Fusarium wilt.
- ‘Deep Purple’ (12-18 in. tall) has vibrant dark purple leaves with sweet basil flavor and a low rate of green off-foliage. Its uniform, upright growth habit makes it a favorite for containers.
- ‘Purple Ball’ (12 in. tall) is ideal for small spaces and containers with its compact, tidy, round growth habit. It forms a dense ball of small, purple-plum leaves that are fragrant and aromatic.
- ‘Rosie’ (12-18 in.) grows strong, upright stems, which makes it easy to harvest and ideal for bouquets it’s especially pretty with its tall lavender flower spikes. The leaves have an intense dark purple-red color with a mild and aromatic basil flavor. ‘Rosie’ has no to little green off-foliage.
How to Grow Purple Basil
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Growing purple basis is very similar to taking care of green basil, whether you plant it in your garden or in pots (and if you have a sunny window, you can even grow it indoors).
Since purple basil comes in different heights, make sure to give your plants sufficient space. Crowded conditions lead to insect and disease issues such as aphids and powdery mildew. If you start purple basil from seed, you will need to thin out the seedlings. The seed package will specify the proper spacing for the variety.
Light
Purple basil needs six to eight hours of full sun every day. Ample sunlight not only ensures that the leaves will be purple but also healthier, stronger plants with fewer disease problems.
Soil
The soil for purple basil should be moist, rich, and well-draining. If the soil is lacking these qualities, amend it with compost before planting. Organic matter not only adds nutrients but also helps to retain soil moisture.
Water
Keeping your purple basil well-watered at all times is key—it is not an herb that tolerates drought. Water slowly but deeply in the absence of rain whenever the top inch of soil feels dry. Use mulch around the plant base to keep moisture in.
Temperature and Humidity
Like green basil, purple basil needs heat to thrive. Don’t plant it until the daytime temperatures remain in the 70s and nighttime temperatures are above 50°F. Basil is very sensitive to cold, which blackens its leaves.
Fertilizer
Unless you are growing purple basil purely as an ornamental and don’t cut it regularly, you need to fertilize the plant frequently. Use an organic slow-release vegetable fertilizer and scatter the granules around the plant base, avoiding the stem.
For faster results, feed it with a liquid organic fertilizer such as fish emulsion. Follow the label directions for the frequency of applications and amounts.
Harvesting
You can start harvesting basil leaves as soon as the plants reach 6 to 8 inches in height. Pick the leaves regularly to keep the foliage growing. Always start harvesting basil leaves from the top of the plant and not the bottom.
The flowers of purple basil are edible too. In addition to using them as a garnish, they also make a gorgeous magenta-colored vinegar.
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Does purple basil exist?
Yes, purple basil does exist, it is a naturally occurring variety of green basil and it is not a novelty—it was first recorded by the British botanist George Bentham in 1830.
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Does purple basil taste different?
Its taste is similar to sweet green or Genovese basil. The flavor intensity of the different cultivars varies but generally purple basis has a strong, almost spicy, more intense aroma.
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Does purple basil need full sun?
Yes, it needs full sun for the leaves to emerge as a purple color. In low light conditions, the plant produces fewer anthocyanins so the basil will be more green than purple.