It is well known for its essential oil, but lemongrass also has culinary and medicinal uses.
Lemongrass is widely cultivated in the tropics and subtropics and prefers warm temperatures and high humidity. It is described as a half-hardy perennial grass that grows in clumps and has a narrow leaf blade and a strong lemony scent when the leaves are rubbed between the fingers.
The leaf can grow 90 cm or more in length. It’s sensitive to frost, but recovers in spring when the weather warms up. When the plant starts growing in spring, cut it back to 15 cm above the ground and clean out all dead growth.
Lemongrass is dormant in winter and the leaves usually turn brown. It’s only necessary to irrigate once every two weeks in winter.
Irrigation can be increased in spring and summer months, depending on soil and climatic conditions. A good rule is to supply water once a week. Keep an eye on the plant in very hot summer conditions to ensure it doesn’t dry out.
The South Africa Department of Agriculture, Forestry and Fisheries production guidelines states that lemongrass grows well in temperatures ranging from 10°C to 33°C. It performs well in sandy to clay loam soils with a pH of 5 to 8,4. Good drainage is essential.
- Lemongrass will produce better-quality oil and a higher yield if propagated from slips obtained by dividing well-grown clumps.
- The guidelines recommend planting at a row spacing of 20 cm and a row width of 40 cm – this will yield 125 000 plants per hectare in high rainfall areas or under irrigation.
- In areas where rainfall is lower, 60 000 plants per hectare is advisable.
- Fertiliser requirements depend on where you farm and the type of soil.
- Don’t use any fertilisers if you haven’t first conducted a soil analysis.
- There may be general fertiliser suggestions for lemongrass, but without the soil analysis you won’t know what the plant needs.
- It‘s generally accepted, though, that lemongrass has a high potassium requirement and that supplying plants with too much nitrogen can reduce oil yields.
- Irrigation isn’t necessary once seedlings are established in areas where the annual rainfall exceeds 650 mm.
- Overhead, flood and drip irrigation can be used, but if your area is prone to rust, avoid using overhead irrigation.
- Hand weeding is labour-intensive, but important, as weeds affect the yield and quality of the oil.
- Lemongrass is susceptible to long smut, stem-boring caterpillars, nematodes, red leaf spot, leaf blight and rust.
DID YOU KNOW?
- Stems and leaves can be harvested.
- When transplanting lemongrass, be sure to dig up the entire clump and lift as much of the root ball as possible.
- Lemongrass can endure droughts, but the plants will have a dry, pale appearance. It should never be allowed to dehydrate completely.
- Lemongrass can be grown as an ornamental pot plant. If planted in a container, repot regularly.
- The leaves and chopped stems give a subtle lemon flavour to soups, stir-fries, marinades, curries, salads and pickles.
- Lemongrass is an essential ingredient in oriental dishes.
- Lemongrass can be added to wax to make insect repelling candles.
- This article was written by Wilma den Hartigh and first appeared in Farming SA.