Gadenin日本語Get the appThe whole year at a glance
Everything lemongrass does is governed by two thresholds: it grows properly above 68F (20C), and it is damaged below 40F (4C). Fix those two points in your own year and the rest of the schedule falls out of them. The table below is written in seasons rather than dates so it reads the same in either hemisphere.
| Season | Main job | Decision point |
|---|---|---|
| Early spring | Divide clumps, start stalks rooting in water | Only once you can keep new divisions above 55F (13C) |
| Late spring | Move plants outside, plant out, begin feeding | After the last frost, when nights hold above 55F (13C) |
| Early summer | Water deeply, feed every two weeks | First stalks reach pencil thickness |
| Mid to late summer | Harvest outer stalks regularly, shear leaf tops if congested | Take up to a third of the clump at a time |
| Early autumn | Last main harvest, stop feeding | Six to eight weeks before your first frost date |
| Late autumn | Lift, pot up or move under cover | Before the first frost, not after it |
| Winter | Keep barely moist, check weekly for mites | Water only when the top half of the pot is dry |
Spring: divide, root and wake it up
Spring is the only good time to divide. As soon as you see new shoots at the base of an overwintered clump, lift it, split it into pieces with two or three stalks each, and pot them individually. Divisions made now have the whole warm season to build root and will be full plants by autumn; divisions made in autumn usually rot.
This is also the moment to start any supermarket stalks in water, so that the rooted plants are ready to go outside as soon as the nights are warm enough. Resist putting anything outdoors early. Lemongrass gains nothing from three weeks in cold spring air, and a late frost undoes the whole start.
- Restart watering gradually An overwintered plant that has been kept dry needs water increased slowly as growth resumes, not a soaking on the first mild day. Wet compost around a barely active root system is how spring losses happen.
- Refresh the compost Even if you are not dividing, knock the plant out, remove the exhausted top inches of compost and pot up into fresh mix a size larger. Last year's compost has nothing left in it.
- Harden off before moving out Give plants a week of days outside and nights back under cover before they stay out permanently. Foliage grown indoors scorches in full sun otherwise.
Summer: the season that makes the crop
Almost all of a year's growth happens in the warm months, so this is where effort pays. Water deeply and often, feed every two weeks, and keep the plant in as much direct sun as you can give it. A clump in full sun with plenty of water and nitrogen will throw new shoots continuously; the same clump kept dry will sit still for weeks.
Start harvesting as soon as outer stalks reach pencil thickness, and keep taking them. Regular harvest is what keeps the middle of the clump open and the new shoots swelling. Waiting until autumn to take everything at once gives you a congested plant and a glut.
In high summer a mature clump in a pot may need water twice a day. If that is not realistic, sink the pot into the ground or move it into a position with afternoon shade, and accept slightly slower growth.
Autumn: stop feeding, then get ahead of the frost
Stop feeding six to eight weeks before your first frost date. Soft nitrogen-driven growth going into cold weather is the tissue that collapses first and lets rot into the crown. Growth slows on its own as nights cool, and that slowdown is your cue to take a last substantial harvest while the stalks are still at their best.
Then act before the frost rather than after it. A plant moved under cover with its foliage intact carries far more stored energy into winter than one moved after it has been frosted, and it restarts much faster in spring.
- Take the main harvest Pull as many usable stalks as you can while trimming the clump down to a manageable size. Freeze what you cannot use in two weeks; frozen stalk keeps its aroma for a year.
- Lift plants from open ground Anywhere that freezes, dig up the clump, cut the foliage back to eight to twelve inches (20 to 30 cm), and pot it into fresh compost. Water once and then keep it only just damp.
- Move pots under cover Bring potted plants in when nights start dropping below 50F (10C), not when frost is forecast. Check the pot for slugs and hose the foliage down before it comes indoors.
Winter: keep it alive, expect nothing
Over winter the aim is survival, not growth. Keep the plant above 50F (10C) with as much light as you can offer, and water only when the top half of the pot is dry, which may be as little as once every two or three weeks. Most winter losses are drowning, not cold. Do not feed at all.
A cool bright room, a frost-free greenhouse or an unheated but sheltered garage all work, with the garage option meaning the plant loses its leaves and sits semi-dormant, which is fine so long as the crown stays firm. Check weekly for spider mites, which is the other winter killer, and rinse the foliage in the sink at the first sign of pale speckling.
Yellowing and leaf loss over winter is normal and is not a reason to water more. Judge the plant by squeezing the base of a stalk: firm means it is alive and waiting for spring.
Building your own calendar
The generic schedule above becomes far more useful once you replace the seasons with your own observed dates. Record four things each year: when new shoots first appeared in spring, when you moved the plant outdoors, when you took the first and last harvest, and when you brought it back under cover. Note the weather around any loss too, because a plant that rotted or froze always has a date attached to it.
After two seasons those dates are more reliable for your garden than any general guidance, and they will usually show that your real growing window is either longer or shorter than you assumed, which changes how many plants you need to keep going.