Gadenin日本語Get the appThe dry shade specialist
There is a particular position in almost every garden that defeats plants: under the skirt of a mature tree, or against a north wall where the eaves keep the rain off, where the soil is dark, root-filled and permanently dry. Most shade shrubs go into that spot, sulk for two years and die. Aucuba does not. It is among the toughest broadleaf evergreens available to a temperate garden, and dry root competition under established trees is exactly the condition it was selected for over a century and a half of use in difficult town gardens.
The reason is structural. Aucuba builds thick, leathery, waxy-surfaced leaves that lose water slowly, and it roots coarsely and deeply enough to hold its own against tree roots once it is established. It also tolerates poor soil, urban air, salt-laden coastal wind at a distance from the sea, and years of neglect. If you have a corner where the previous three shrubs have failed, this is the plant to try next.
Understand what tolerance means, though. Tolerating dry shade is not the same as preferring drought. A newly planted aucuba in root-filled soil under a tree needs watering through its first two summers, because it has to establish against competition that is already there. Skip that and it will sit at planting size for years or fail outright, which is where the plant's reputation for being slow comes from.
The two conditions it will not take: sun and cold wind
Aucuba's weakness is the flip side of its big leaves. In full sun, particularly hot afternoon sun, the leaf surface heats faster than the plant can cool it and the tissue dies in patches. What you get is black or dark brown scorch along the leaf margins and in irregular blotches across the blade, sometimes with a bleached yellow zone around it. It is permanent. Aucuba holds each leaf for two or three years, so a single bad summer's scorch stays on display until those leaves are shed.
Cold drying wind in winter produces almost identical damage, and for the same underlying reason: the leaf loses water it cannot replace, because the soil is frozen or the roots are too cold to work. Blackened margins that appear after a hard windy cold spell are wind burn, not frost damage in the usual sense, and they are worst on the side of the plant the wind comes from. Sun scorch is worst on the side facing the light. That difference in pattern is how you tell them apart.
So the site test is simple. Shade for most of the day, especially through the afternoon. Shelter from the prevailing winter wind, whether from a wall, a fence, a hedge or a building. Anything else about the soil is negotiable: heavy clay, thin chalky ground, sandy soil, root-choked ground under a beech, town soil full of rubble. It will take all of them, provided water does not physically stand on the surface for days after rain.
| Site condition | Verdict | What you will see if you get it wrong |
|---|---|---|
| Deep dry shade under a mature tree | Ideal | Nothing, once it is through its first two summers |
| North-facing wall or shaded side passage | Ideal | Nothing. This is the classic position |
| Dappled light through a high canopy | Very good | Occasional small scorch mark on the top leaves |
| Morning sun, shaded from midday | Acceptable in cool climates | Slight yellowing of the uppermost leaves in high summer |
| Full afternoon sun | Wrong | Black-edged leaves and dark blotches that never recover |
| Exposed to cold winter wind | Wrong | Blackened margins on the windward side after a freeze |
| Ground where water stands after rain | Wrong | Yellowing lower leaves, then collapse in a wet winter |
| Heavy clay that drains slowly but does not pond | Fine | Nothing. Plant slightly proud and mulch |
Male and female plants, and where the berries come from
Aucuba carries male and female flowers on separate plants. A female plant produces the scarlet berries the shrub is grown for; a male produces none, ever, no matter how healthy it is or how long you wait. This single fact accounts for most of the disappointment people feel with aucuba, and it is worth settling before you dig rather than after four berryless autumns.
A lone female with no male within range will flower and then drop every unpollinated flower. So plan for a pair, or at least a group: one male will pollinate several females planted within roughly fifty feet (15 m), and closer is better in a sheltered garden where insects and air movement have less to work with. If you are planting a shaded boundary run, put a male somewhere in the middle of the group rather than at one end.
You can sex a mature plant by looking at the flower clusters in spring. Both sexes carry small dull purple-brown flowers in loose upright heads, but the male heads are larger and more branched and are obviously full of stamens carrying pale pollen, while the female heads are shorter and sparser with a small green ovary at the center of each flower. A young plant may take three or four years to flower at all, so if berries matter, buy plants old enough to have flowered, or accept the wait.
One consolation: an all-male or all-female planting is still a first-rate evergreen. The leaves are the year-round performance and the berries are the bonus. But if berries are the reason you wanted it, get the pairing right at planting time.
Planting, step by step
Autumn and early spring are both good planting seasons, with autumn better in mild climates because the roots get months of cool damp soil before their first dry spell. Avoid midsummer planting; the leaf area is too large for a disturbed root system to keep supplied. Allow real space: a settled plant reaches six to ten feet (2 to 3 m) tall and nearly as wide, and it does that faster in decent soil than its slow reputation suggests.
- Soak the root ball before it goes in the ground Stand the pot in a bucket of water until bubbles stop rising, usually about twenty minutes. A dry root ball planted into dry shade under a tree will never wet up from above, because water runs around it instead of into it, and the plant slowly starves in the middle of damp soil.
- Dig a wide hole and cut the tree roots you meet Make the hole two to three times the width of the pot and no deeper than the root ball is tall. Under an established tree you will hit roots. Cut anything up to about an inch (2.5 cm) thick cleanly with loppers; leave anything larger and shift the hole sideways rather than sawing through a structural root.
- Improve the whole area, not just the hole Fork two to four inches (5 to 10 cm) of leaf mold or garden compost across the planting area and lightly into the top spit. Enriching only the hole makes a sump that holds water in heavy ground and gives the roots no reason to leave the pocket you dug.
- Set the crown level with the surrounding soil The junction of stem and roots sits exactly at finished soil level, or half an inch (1 cm) proud on heavy clay. Planted too deep, the stem base stays wet and rots. Planted too high, the root ball dries out and the plant never establishes.
- Firm, water heavily, then mulch Firm with your heel around the edge of the root ball rather than on top of it. Water with two full cans, then lay two inches (5 cm) of bark or leaf mold over the whole area, keeping it an inch clear of the stem. The mulch matters more here than for most shrubs because it is holding moisture against tree root competition.
- Water through two full summers, then stop A full can per plant every week through dry weather for the first two growing seasons. After that an established aucuba in shade needs no watering at all except in an exceptional drought, and routine watering from year three onward does more harm than good.
Record the planting date, whether the plant is male or female if you know, and its position relative to the others in the group. Three years later, when one plant berries and another does not, that note is the difference between understanding your planting and guessing at it.