Lemon grass (Cymbopogon spp.) reproduces by growing new shoots from the base of the plant, and this is the area that provides the best cuttings. Frost-tender, perennial plants, lemon grass varieties include culinary lemon grass (Cymbopogon citratus) and citronella grass (Cymbopogon nardus), a decorative plant that produces the signature citronella oil. Lemon grass grows outdoors in U.S. Department of Agriculture plant hardiness zones 10 through 11, and citronella grass grows in USDA zones 10 through 12. Citronella grass is also called mana grass, nardus and nard grass.
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Propagating From Clumps
A single clump of lemon grass can provide many new plants. Lemon grass clumps grow steadily wider through the growing season, and you can remove small pieces of plant with roots attached from the edge of a clump. The best time for propagating lemon grass from clumps is late fall or early winter, when the plants have stopped growing.
Things You'll Need
- Sharp trowel or spade
- Rubbing alcohol
- Pruning shears or knife
- 3-inch plant pot with drainage holes
Cut vertically through the edge of the base of a lemon grass plant into the soil with a sharp trowel, so you slice off a section of shoots 1/2 to 1 inch wide and their attached roots. If the clump is large and the root system is deep, you may need to use a sharp spade to cut all the way through the roots.
Wipe pruning shear blades or the blade of a pruning knife with a cloth dipped in rubbing alcohol.
Prune the removed lemon grass section's leaves to 5 or 6 inches long. Prune the roots to shorten them so that they will fit in a 3-inch plant pot with drainage holes. Wipe the pruning shears or pruning knife blade with rubbing alcohol when you've finished.
Fill the plant pot to 1/2 inch below the rim with freely draining potting soil, such as potting soil for cuttings or seedlings. Make a hole in the center of the soil large enough to hold the roots of the lemon grass section.
Place the lemon grass section in the plant pot so that it sits at its original growing depth. Fill in the gaps around its roots with potting soil.
Water the lemon grass section until water flows through the drainage holes in the plant pot, and place the pot in a warm, sunny spot indoors if you get frosts in your area. In frost-free climates, place the pot outdoors in a sunny area sheltered from winds.
Water the lemon grass section when the soil surface is dry.
Rooting Lemon Grass From a Grocery Store Stem
Culinary lemon grass stems sold in grocery stores often sprout roots when left in a glass of water for several weeks. Place two or three stems in a clean glass jar and fill the jar with clean water. Change the water every day. Roots usually form within two to three weeks. When the roots are 2 to 3 inches long, plant each stem in a 3-inch plant pot with drainage holes and freely draining potting soil, and care for the plants in the same way as sections taken from lemon grass clumps.
Select stems that have large base plates for the best chances of success.
Planting in the Garden
When lemon grass roots appear through the drainage holes in the pot, the plant is ready for planting into the garden.
In areas that experience frosts, wait until after the last frost before planting lemon grass outdoors.
Plant the new lemon grass plants in an area that receives at least six hours of direct sun each day. Lemon grass tolerates most soils, but it grows best in organically rich soil that drains well.
Dig a hole the same depth as the plant pot and about 1 1/2 times as wide. Remove the plant from its pot and place it in the hole at its original growing depth. Fill in the gaps around its roots with dug soil. Space lemon grass plants 2 feet apart.
Lemon grass thrives in evenly moist soil and with regular applications of liquid fertilizer. Water lemon grass when the soil is dry to a depth of 1/2 inch, applying enough water to moisten the soil to the base of the root ball.
To fertilize lemon grass, dissolve 2 teaspoons of a water-soluble, 24-8-16 fertilizer in 1 gallon of water and apply the solution every week. One gallon feeds 10 square feet of lemon grass plants.