Types of Basil: Sweet Thai Lemon plus More
The main types of basil fall into a few groups. University of Illinois Extension sorts them into sweet, Genovese, bush plus purple groups, plus other basils with distinct aromas such as cinnamon, lemon, clove plus Thai. UF/IFAS describes four groups: sweet green, dwarf green, purple leaf plus scented leaf.
The short answer
Most basil is Ocimum basilicum, a tender annual in the mint family. NC State Extension notes Thai plus Genovese basil are cultivars of it. Types vary in leaf size, color plus scent, from large lettuce leaf kinds to half inch leaves. Holy basil is a separate species, Ocimum tenuiflorum, with a purple cast plus spicy fragrance.
What are the main types of basil?
University of Illinois Extension lists sweet basils such as Napoletano, the Genovese group, a bush group with smaller rounded forms such as Spicy Globe plus a purple group with dark purple to bronze foliage. Other basils carry distinct aromas: cinnamon, lemon, clove plus Thai.
| Type | Leaves | Scent or trait |
|---|---|---|
| Sweet | Large, lettuce like leaves | Familiar sweet scent |
| Genovese | Classic large leaf | From the Genoa area of Italy |
| Bush | Small, fine textured | Rounded, compact form |
| Purple | Dark purple to bronze | Ornamental color |
| Thai | Green leaves | Licorice like aroma |
| Lemon | Green leaves | Intense lemon fragrance |
| Cinnamon | Green leaves | Cinnamon aroma |
Source: University of Illinois Extension.
How do their aromas differ?
University of Illinois Extension describes Thai basil with a licorice like aroma, lemon basil with an intense lemon fragrance, clove basil with clove scented leaves plus cinnamon basil with a distinct cinnamon aroma. UF/IFAS notes basil scents vary because each variety holds different types plus amounts of aromatic oils, with lemon plus lime types giving a mild citrus aroma.
How is holy basil different?
NC State Extension notes holy basil, Ocimum tenuiflorum, is an annual or short lived perennial subshrub from southern Asia. Compared with sweet basil, its leaves tend to have a purple cast, its flowers are smaller plus it is shorter lived. It grows rapidly to 3 feet plus self sows, so a container helps manage its spread.
How to: step by step
- Compare leaf size, from large lettuce leaf to half inch.
- Check leaf color, from green to purple.
- Crush a leaf plus smell it.
- Study the plant form, upright or rounded bush.
- Grow plants in full sun after the last frost.
- Pinch off tips plus flower buds for bushier growth.
Troubleshooting
Leaves turn black: cold. UF/IFAS notes leaves of many varieties blacken plus drop below 40 F.
Plant flowers early: flower buds left on. University of Illinois Extension suggests pinching buds as soon as they form.
Slow, weak growth: poor soil. University of Illinois Extension notes basil grows slowly in soils low in nutrients.
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Sources
- Basil, University of Illinois Extension
- Basil, UF/IFAS Gardening Solutions
- Ocimum basilicum (basil), NC State Extension Gardener Plant Toolbox
- Ocimum tenuiflorum (holy basil), NC State Extension Gardener Plant Toolbox
FAQ
Which basil types suit containers?
UF/IFAS notes miniature basils such as Dwarf Greek plus Spicy Globe are great for containers, while larger types like Greek Column can reach 3 feet plus suit a bed. NC State Extension notes purple leaf sweet basil cultivars look showy in containers plus window boxes. Containers also give basil good drainage.
Can basil grow indoors?
Seedlings start well indoors. University of Illinois Extension notes basil seeds sprout in about 5 to 7 days when the medium stays at least 70 F. Allow 3 to 4 weeks to grow transplants. Move them out well after the frost free date, once soil reaches at least 60 F.
Why is my basil flowering?
Basil flowers as it matures. UF/IFAS notes letting the plant flower plus set seed will shorten its growing season, so pinch flowers as they form to focus energy on leaves. University of Illinois Extension notes pinching stem tips also encourages a bushy plant with more leaf growth. Harvest regularly to spur branching.
Does basil come back every year?
Usually not. University of Illinois Extension calls basil a tender annual, plus UF/IFAS notes most basils are annuals in Florida, though a few behave as perennials. Holy basil may live as a short lived perennial. University of Illinois Extension notes basil can also be grown from tip cuttings of overwintered plants.
How cold can basil get?
Not very. UF/IFAS notes leaves of many basil varieties turn black plus drop off below 40 F, so cover plants on cold nights. Wait until nights stay above 55 F to plant in spring. University of Illinois Extension notes cold soil plus air can stunt basil plus blacken leaves at 50 F.
