Gadenin日本語Get the appWatering: the first two years, then hardly ever
Aucuba's watering needs split cleanly into two phases and the mistake is treating them the same. For the first two growing seasons the plant is competing for water against whatever is already rooted in that ground, and it needs a full can once a week through dry weather. After two seasons the root system is deep and coarse enough to look after itself, and from that point on the plant in the ground needs watering only in an exceptional drought.
That second phase is longer than people expect and much drier than they are comfortable with. An aucuba under a tree can go an entire summer without rain reaching its roots and show nothing worse than slightly dull leaves. Watering it anyway, week after week, keeps the surface layer permanently damp, which encourages shallow rooting and does the plant no favors at all.
The test that works in either phase is your finger, pushed two inches (5 cm) into the soil under the mulch. Damp means wait. Dry at that depth on a plant under two years old means water thoroughly and then leave it. On an older plant, dry at that depth is normal and you do nothing unless the leaves are actually drooping, which on this shrub takes a serious drought.
In a container the rhythm is faster and the risk reverses. Pots dry out in days in summer and drown in winter. Water until it runs from the base, tip out any saucer, and wait until the top two inches are dry before doing it again. From late autumn until growth restarts, cut the frequency by half or more. Winter overwatering in a cold pot is the commonest way a container aucuba is killed.
| Symptom | Most likely cause | What to do |
|---|---|---|
| Black or dark brown leaf margins and blotches | Sun scorch or cold wind burn | Look at the exposure. Feeding will not fix it |
| Damage worst on the side facing the light | Sun scorch | Shade it or move it in autumn or spring |
| Damage worst on the windward side after a freeze | Winter wind burn | Put a mesh windbreak on the prevailing side |
| Lower leaves yellow, soil dark and heavy | Roots standing wet | Stop watering, improve drainage, check the pot holes |
| Whole plant limp with bone dry soil | Drought on a plant under two years old | Soak thoroughly. It usually recovers within a day |
| Flowers every spring, never any berries | Male plant, or a female with no male nearby | Check the flower structure before blaming the care |
| Leaves cut in half with brown edges | The plant has been sheared instead of cut | Prune with pruners at the stem from now on |
| Bare legs, all foliage at the top | Age, or too little light even for aucuba | Cut back hard in spring. It shoots from old wood |
Feeding: mulch instead
An aucuba in ordinary garden soil with an annual mulch needs no fertilizer at all. Two inches (5 cm) of leaf mold or garden compost spread over the root area each spring feeds it slowly, holds moisture through the summer and keeps the surface roots cool, which is the whole of its requirement. Under a tree the mulch is doing more work than it would elsewhere, because it is replacing the leaf litter the plant would have had in the wild.
Adding a high-nitrogen feed on top of that is actively counterproductive. It pushes long soft shoots with widely spaced leaves, which flop, scorch more readily than firm growth and make the plant go leggy years earlier than it would have. If a shrub is growing slowly in dry shade, the limit is nearly always water or light, not nutrients, and fertilizer cannot supply either.
Container plants are the exception, because every watering flushes nutrients out of the drainage holes. One application of a balanced slow-release granular feed as growth starts in spring covers the season. Stop all feeding from midsummer so the growth firms up before cold weather; soft late shoots are the ones that blacken first in a windy freeze.
Uniform yellowing across old and new leaves alike is a light or water problem. Yellowing confined to the newest leaves while the older ones stay dark, typically in a pot watered with hard tap water, points to iron shortage and responds to a chelated iron drench rather than a general feed.
Keeping the leaves clean and undamaged
The leathery, glossy leaf is the reason to grow this plant, and because each one is held for two or three years, everything that happens to it stays on show for a long time. There is no treatment that repairs a damaged leaf. Care of the foliage is therefore entirely about prevention, plus removing the leaves that are past saving.
Take off badly scorched or blackened leaves by cutting the stalk close to the stem with pruners, rather than pulling them, which tears bark and leaves a stub that dies back. Doing this in spring, when you can see the whole winter's damage at once, tidies the plant in twenty minutes and lets the new growth take over the silhouette.
Indoors and in dry city air, wipe the upper surfaces with a damp cloth two or three times a year, supporting each leaf from underneath. The point is only partly the shine; it forces you to look at the undersides, where scale and mealybug always begin. Leaf shine products clog the surface and are not worth using on a leaf this reflective to start with.
One genuine hazard is worth naming: aucuba berries and leaves are mildly toxic if eaten, enough to cause stomach upset in a child or a pet. It is not a reason to avoid the plant, which has been a standard town shrub for generations, but it is a reason to sweep up fallen berries where small children play.
What to write down
Two records make everything about this plant easier. The first is the sex of each plant and its position, noted the first spring it flowers. Aucuba is grown in groups more often than singly, and once you know which of five plants along a boundary is the male, you know why the far end never berries and whether moving one plant would fix it.
The second is the date and pattern of any leaf damage. Write down when the blackening appeared and which side of the plant it is on. Damage that shows up after a hot dry spell on the sunny side is scorch and tells you to shade or move the plant. Damage that appears after a windy freeze on the exposed side is wind burn and tells you to put up a screen. The two look nearly identical on the leaf, and without a note of when they appeared you will spend the next season treating the wrong one.
It is also worth recording the date you first find scale in the year and where on the plant it was, because scale returns to the same inner shaded stems each spring and a two-line note turns next year's inspection into a two-minute check.
One more note that pays off: the date each spring when new growth starts to extend. Aucuba is slow to start and that date, kept over three years, tells you whether an odd-looking spring is really late or just feels late.