Gadenin日本語Get the appA bare plant is almost never a dead plant
More lemon verbena plants are thrown on the compost pile alive than are ever actually killed. It is a woody deciduous shrub, not an evergreen herb like rosemary or bay, and dropping every single leaf is normal behavior rather than a symptom. It does this in autumn when nights cool, it does it again if you carry the pot indoors, and it will do it a third time in a week if you move it from a shady spot into full sun. Within a few days you are holding what looks like a bundle of dry sticks.
The test is simple and takes five seconds. Scratch the bark of a pencil-thick stem with a thumbnail. Green or pale cream underneath means the wood is alive and will break bud again. Brown and dry all the way through, and snapping cleanly with no flex, means that stem is dead, though the base may still be sound. Work down the plant from the tips until you find green, and you will usually find it.
The other thing to understand is that lemon verbena breaks bud late. It is one of the last plants in the garden to wake up, often weeks after everything around it is in full leaf. A plant that is still bare while the mint has filled its pot is not lost; it is waiting for consistent warmth. Keep it barely moist and keep it patient, and buds swell along the older wood once nights hold above about 50F (10C).
| What you see | What it means | What to do |
|---|---|---|
| All leaves drop within days of moving the pot | Shock response to a change in light or temperature | Leave it where it is, water sparingly, wait two to three weeks |
| Leaves drop as autumn nights cool | Normal onset of dormancy | Reduce water, move it to shelter, stop feeding |
| Stems still green under the bark, no buds in spring | Waking late, which is usual for this plant | Keep barely moist and warm; do not cut yet |
| Lower leaves yellow and fall in summer | Root ball dried out completely or is waterlogged | Check the weight of the pot and correct the extreme |
| Wood brown and brittle right down to soil level | That stem is genuinely dead | Cut back to live wood, or to the base if the crown is still firm |
Water on weight, not on schedule
In full growth lemon verbena drinks hard. A well-rooted plant in a twelve inch (30 cm) pot in a warm, breezy spot can empty itself in a day, and the first sign is the whole plant folding limp. It recovers from one wilt without lasting harm, but repeated wilting scorches the leaf margins brown and costs you the fragrance you grew it for.
Water thoroughly when the top two inches (5 cm) are dry, and water until it runs from the drainage holes. Little and often keeps the surface damp while the middle of the root ball stays bone dry, which is how a plant wilts in wet compost. Learn the weight of the pot straight after a soak and again three days later, and you will stop guessing.
The rule inverts completely once the leaves go. A bare, dormant plant is not drinking and its roots rot easily in cold wet compost. Through the dormant months it wants no more than a splash every three or four weeks, just enough that the root ball never turns to dust. Watering a leafless verbena on a summer rhythm is the single commonest way to kill one.
- Feel two inches down before every watering Push a finger in to the second knuckle. Surface compost dries within hours in warm weather and tells you nothing about the roots below it.
- Soak until it runs through Add water until it comes freely out of the base, then stop. This flushes accumulated salts and wets the whole root ball rather than the top third.
- Empty the saucer straight away The main working roots sit in the bottom inch of the pot, and standing water keeps that layer permanently airless. Tip it out, or stand the pot on feet.
- Rescue a bone-dry pot in a bucket If water runs down the gap between compost and pot and straight out, the root ball has shrunk. Stand the whole pot in water for twenty to thirty minutes until bubbles stop.
Feed a leaf crop, but not into autumn
You are growing this plant for foliage, and it makes a great deal of it in one season, so it feeds harder than most woody herbs. A balanced liquid feed at label strength every two weeks through the growing season keeps the leaves large, soft and strongly scented. Slow-release granules worked into the top of the compost as growth begins are an easy alternative for a single plant.
A pot-grown verbena also strips its compost quickly. Repot into a container one size larger each spring as growth starts, using a free-draining mix with a third grit or perlite, or if the pot is already as large as you want, tip the plant out, cut an inch (2.5 cm) off the outside of the root ball all round and put it back with fresh compost.
Stop all feeding as summer ends. Late feeding pushes soft green growth that has no time to harden, and that soft growth is the first thing to blacken in the first cold nights. A plant that is allowed to slow down and ripen its wood comes through the dormant months far better than one still growing when the cold arrives.
Lemon verbena is intolerant of cold wet feet in a way it is not intolerant of drought. If you only change one thing about the growing mix, add grit. A third grit by volume in a soil-based compost solves more verbena problems than any feeding regime.
Pinch through summer to keep it leafy
This is a shrub, and left alone it behaves like one: it puts everything into a few long, bare, whippy stems with leaves only at the tips. That is fine for a plant in a border and useless for a plant you pick from. Regular pinching is what keeps it a dense, leafy bush instead of a set of poles.
Through the growing season, take the top two pairs of leaves off any shoot that runs away from the shape you want. Every pinch turns one growing point into two, and repeated over a season it doubles and redoubles the number of shoots carrying pickable leaves. The tips you remove are usable, so nothing is wasted.
Do not pinch late in the season. Anything you cut once nights are cooling forces soft regrowth that will not ripen. The last pinch of the year should come well before the first cold nights, and after that the plant should be left to slow down on its own. The hard structural cutback belongs in spring, once you can see which wood came through.
Keeping a record that pays off next year
Lemon verbena is a plant with two or three decisions a year that matter enormously, and they are exactly the decisions people cannot remember twelve months later. Notes turn a plant you gamble on into a plant you manage.
Write down the date the last leaf fell and the date the first bud broke in spring, and after two seasons you will know your own plant's dormant window rather than worrying every year that it has died. Record the temperature or the weather at which the leaf drop started, because that tells you how many weeks of warning you get before you need to move it. Record the date you cut it back and how far down you cut, along with how vigorously it responded, so you can be braver or gentler next spring. Record the pot size and the date you last repotted, since a plant that has gone three years in the same compost will underperform for reasons nothing else explains. Finally, note where the pot stood, because the difference between a hot sheltered wall and an open, breezy spot shows up in leaf size, in how often you had to water, and in how strongly the leaves smell when you rub them.