Gadenin日本語Get the appLight decides the color
The red and bronze coloring that nandina is grown for is not a fixed property of the plant. It is a response to two conditions acting together: strong light and cold. The same clump that turns deep crimson in an open sunny bed through a cold winter will stay flat mid-green all year in shade under trees, and neither plant is doing anything wrong.
Full sun to about half a day of direct light gives the strongest color, the densest cane production and the heaviest flowering and fruiting. Deep shade gives you a green, thinner, taller plant with fewer canes and little fruit. Both are perfectly healthy and it is genuinely a matter of what you want from the position, but do not plant in shade and then expect the color from the catalogue photograph.
The cold half of the equation is why the color arrives in autumn and deepens through winter, and why a plant in a mild coastal garden colors less than the same plant inland. In a hot climate, accept afternoon shade instead, because leaves in relentless sun with dry soil scorch at the edges rather than coloring.
Soil and drainage
Nandina is not fussy about soil texture and will grow in clay, loam or sand, but it is unforgiving about standing water. Choose a spot that drains after heavy rain. If you are unsure, dig a hole a foot (30 cm) deep, fill it with water, and see how long it takes to empty. Anything still holding water after several hours is a site where the plant will eventually be lost to root rot.
Soil pH matters more than most guides suggest. On alkaline soil, especially in a narrow bed against a house foundation where mortar and rubble have raised the pH, the plant grows but the new foliage comes through yellow with green veins. Work composted pine bark or leaf mold through the bed before planting and plan on an acidifying mulch every year.
Established plants are notably drought tolerant, including under trees. That tolerance is earned over two seasons and does not apply to something planted last month.
Spacing for a clump that spreads
This is where planting plans usually go wrong. Nandina spreads sideways from a running root system, sending up new canes at the edge of the clump and gradually widening. A young plant from a container looks like a neat vertical tuft and gives no hint of the width it will occupy in five years.
Give a specimen plant three to four feet (90 to 120 cm) of clear space all round. For a run along a path, set plants two and a half to three feet (75 to 90 cm) apart and accept that they will knit into a band within three or four years. Planting tight guarantees a congested thicket.
Keep the crown at least two feet (60 cm) back from a lawn edge, because canes coming up in grass are a nuisance. Where spread must be contained, a root barrier sunk to eighteen inches (45 cm) at planting time is far easier than digging out escaped canes later. In a container the plant is well behaved and long-lived, but the reservoir is small: use a pot at least fourteen inches (35 cm) across and check it daily in summer.
| Situation | Spacing or size | What to expect |
|---|---|---|
| Single specimen | Three to four feet (90 to 120 cm) clear all round | A distinct clump that widens slowly and stays readable |
| Continuous band along a path | Two and a half to three feet (75 to 90 cm) apart | Plants knitting together in three to four years |
| Foundation bed | At least two feet (60 cm) out from the wall | Room to prune from behind and less alkaline soil trouble |
| Under established trees | Three feet (90 cm) apart, watered for two years | Green rather than red foliage, fewer berries, good tolerance |
| Container | Pot at least fourteen inches (35 cm) across | Contained, long-lived, needs daily checking in summer |
| Where spread must be stopped | Root barrier to eighteen inches (45 cm) deep | Canes stay inside the intended area |
Getting it in the ground
Autumn is the best planting season in most climates, while the soil is still warm and the plant is heading into dormancy, which gives the roots months to establish before their first summer. Early spring is the second choice. Avoid planting into the middle of summer heat unless you can commit to weekly watering for the rest of the season.
- Water the plant thoroughly before you start Soak the root ball in its container until bubbles stop rising. A dry root ball planted into moist soil often stays dry, because water runs around it through the surrounding earth rather than into it.
- Dig wide, not deep Make the hole two to three times the width of the root ball but no deeper than its height. Roots spread sideways, and a hole dug deeper than the root ball lets the plant settle and sink over the following months.
- Loosen the outer roots Tease the roots free around the sides and base of the root ball, and cut through any that are circling the pot shape. Roots left circling stay circling and the plant never anchors properly.
- Set the crown at or slightly above soil level The point where the canes emerge from the roots must not be buried. Planting deep is the most common cause of a new nandina rotting at the base during its first wet winter.
- Backfill with the soil you dug out Use the native soil rather than filling the hole with rich compost. A pocket of soft compost in heavy ground becomes a sump that holds water and discourages roots from leaving the hole.
- Water in and mulch, keeping the mulch off the canes Soak the plant so the soil settles around the roots, then spread two inches (5 cm) of composted bark over the root area, kept a hand's width clear of the cane bases so the wood does not sit wet.
Record the planting date and sketch the position of the clump edge relative to a fixed point such as a path or a post. Two or three years on, that sketch tells you exactly how fast the clump is spreading, which is the number that decides whether you need a barrier.
The first two years
Water a new plant deeply once a week through its first growing season and through any drought in the second, using two to three gallons (9 to 14 liters) delivered slowly rather than a daily sprinkle. Slow soaking reaches the working roots; light watering wets the top inch and pulls roots upward into the layer that dries out first.
Do not feed at planting time and do not feed heavily in the first year. A new plant is building roots, and nitrogen at that stage produces soft top growth the roots cannot support. An annual mulch in early spring is enough. Do not prune at all in the first two years beyond removing anything dead: the plant needs a population of canes before the renewal cycle makes any sense.
Check the rules before you plant
One question is worth settling before the plant goes in the ground. In parts of the southeastern United States nandina has escaped from gardens into woodland, where it forms dense stands and displaces native understorey plants. Birds carry the seed from garden fruit into wild ground, so an ordinary domestic plant is the source. Some jurisdictions list it as invasive and some restrict its sale.
If that applies where you garden, you have two honest options: plant something else, or commit to cutting off every fruit cluster every single year before the birds get to it. The second is a five minute job on a mature clump, but it has to happen annually and it has to happen before the berries soften. A plant that fruits unattended for a couple of seasons has already done the damage.
Outside those areas the seedlings that appear near the parent are easy to pull while small. Even so, removing the fruit is worth doing for a separate reason: the berries are toxic to birds that gorge on them.