Gadenin日本語Get the appWhat a good young plant looks like
A newly rooted stalk should have several white roots at least two inches (5 cm) long and one green shoot pushing up from the center of the base. A small division should have two or three stalks with a visible root plate underneath. Either way, the useful sign of life is a new leaf: until a young lemongrass has produced a leaf that was not there when you planted it, it has not started.
The base should be firm when squeezed. A soft base, or one with a sour smell, is rot, and no amount of care recovers it. Start again with fresh material rather than nursing it along.
Expect no visible progress for the first ten to fourteen days after potting. The plant is replacing brittle water roots with soil roots during that time, and this pause is normal, not failure.
The right pot and mix to start in
Start small. A four to six inch (10 to 15 cm) pot is right for a rooted stalk or a two-stalk division. A large pot around a small root system holds water the plant cannot use, and cold wet compost at this stage is the main cause of losses. Pot up as the roots fill each size rather than trying to save a step.
Use a standard potting mix lightened with about a third by volume of coarse grit or perlite. Lemongrass wants moisture and drainage at the same time, and pure fine compost delivers only the first.
- Plant shallow Set the base so the point where new shoots emerge sits at or a fraction above the compost surface, with only about an inch (2.5 cm) of the base buried. Deep planting buries the crown and rots it.
- Firm gently and water in Press the compost around the base with your fingertips, enough to hold the stalk upright without rocking, and water once thoroughly so the compost settles against the roots.
- Support a wobbly stalk A tall rooted stalk can rock in the wind and shear off its new roots. Push a short cane in beside it and tie loosely, or shorten the leaves further, for the first few weeks.
Warmth and light in the first weeks
Young lemongrass wants 70 to 80F (21 to 27C) and bright light. Below 60F (15C) it effectively stops and simply sits in wet compost, which is where young plants are lost. If nights are still cool, keep new plants indoors or under cover and be patient rather than putting them out early.
Bright light matters, but a plant that rooted on a windowsill will scorch if it goes straight into full outdoor sun. Give it a week of increasing exposure first: a few hours of morning sun to begin with, building to a full day. Scorched blades go papery and white at the tips and do not recover, though the plant will push new ones.
| Stage | Temperature to aim for | Light | Watering |
|---|---|---|---|
| Rooting in water | 70 to 80F (21 to 27C) | Bright, no direct sun | Change the water every day or two |
| First two weeks in a pot | 70 to 80F (21 to 27C) | Bright, indirect | Evenly damp, never soaking |
| Weeks three to six | Above 65F (18C) | Increasing direct sun | Water when the top inch (2.5 cm) is dry |
| After the first new leaves | Outdoor warmth, full sun | Six or more hours direct | Deep watering, allow the top to dry between |
When to start feeding and potting up
Do not feed for the first three or four weeks. There is nothing to feed until roots exist, and fertilizer salts in a barely rooted pot cause more harm than the nutrients do good. Once the plant has produced two or three new leaves and is visibly growing, start a half-strength balanced liquid feed every two weeks and build to full strength.
Pot up when roots appear at the drainage holes, typically six to eight weeks after potting a rooted stalk in warm conditions. Go up one size at a time, ending in a ten to twelve inch (25 to 30 cm) pot by the end of the first season. A young plant that stays in a small pot too long dries out daily and produces permanently thin stalks.
- Check the roots before you pot on Slide the plant out and look. If the compost holds together with white roots visible around the outside, move up a size. If it falls apart, put it back and wait.
- Do not skip pot sizes Moving a six inch (15 cm) rootball straight into a twelve inch (30 cm) pot leaves a mass of wet unused compost around it, which stays cold and sour.
- Plant out at the same depth If it is going into open ground, plant at the depth it was in the pot, space plants two to three feet (60 to 90 cm) apart, and water daily for the first fortnight.
The first harvest, and what to write down
Resist harvesting from a young plant until it has at least six or seven stalks and the outer ones are pencil thick, which normally takes three to four months of warm weather from a rooted stalk and about ten weeks from a division. Taking stalks earlier costs you the growth that would have built the clump, and the stalks themselves are all sheath and no substance.
Record the date you potted each young plant, the date you saw the first new leaf, and the date it was potted up. The gap between potting and that first new leaf is the single most useful number you will collect: it tells you whether your conditions are warm enough, and comparing it between plants started in different places settles the question of where to raise them next year. Note the pot sizes too, since first-season pot size and final stalk thickness track each other closely.