Gadenin日本語Get the appWatering: less than you think, once established
Nandina earns its reputation as a tough plant after about two seasons in the ground. From that point an established clump in open soil handles ordinary dry spells without help, and copes with dry shade under trees better than almost anything else evergreen, which is why it turns up in so many difficult positions.
Until then, treat it as a new plant. Water deeply once a week through the first growing season and through any real drought in the second, giving two to three gallons (9 to 14 liters) slowly over the root area rather than a light daily sprinkle. Slow soaking reaches the depth the working roots occupy; frequent shallow watering trains roots up into the layer that dries out first.
Once established, water only in droughts lasting more than two or three weeks in the growing season. Check before you do: push a trowel in four inches (10 cm) and water only if it is dry at that depth. Foliage looking dull in the middle of a hot afternoon is not a signal; foliage still limp early in the morning is.
Containers are the exception and need checking every day through summer heat. A potted plant has a fixed reservoir and no way to reach further, and the first sign of shortage is browning along the leaf edges that never fully recovers.
Feeding: mulch is usually the whole program
Most nandina that looks poor is short of light, sitting in wet ground, or congested with old canes. Very little of it is short of fertilizer, and feeding a plant with one of those other problems makes it worse rather than better.
The standard routine is an annual mulch and nothing else. In early spring, spread two inches (5 cm) of composted bark, leaf mold or garden compost over the root area, kept a hand's width clear of the cane bases so the wood is not sitting wet. That feeds slowly, holds summer moisture, suppresses competing grass, and on alkaline soil the bark or leaf mold also nudges the surface pH in a useful direction.
Use an actual fertilizer only in three cases: a plant in a container, a plant on very thin sandy soil, or one showing genuinely pale, small, weak new growth. Then apply a balanced slow-release feed once in early spring at the stated rate. Do not feed after midsummer, because soft late growth does not ripen before winter and is the growth that browns in the first hard frost.
| Task | How often | Detail |
|---|---|---|
| Mulch | Once a year, early spring | Two inches (5 cm), kept clear of the cane bases |
| Deep watering | Only in droughts over two weeks | Two to three gallons (9 to 14 liters), slowly |
| Container watering | Check daily in summer | Water when the top two inches (5 cm) are dry |
| Fertilizer | Rarely, never after midsummer | Balanced slow-release, only on poor or potted plants |
| Cane renewal | Once a year, late winter | A third of the canes to the ground, plus staggered cuts |
| Berry removal | Once a year, as fruit colors | Cut each cluster back to the first leaf below it |
| Clearing inside the clump | Once a year, with the renewal cut | Pull out dead canes, old leaves and weeds at the base |
| Iron or acidifying treatment | Yearly on alkaline soil only | Chelated iron or sulfur, if new leaves yellow between green veins |
Managing the leaf color
The color of nandina foliage is a response to conditions rather than a fixed characteristic, and knowing which lever to pull saves a lot of disappointment. Two things drive the red: strong light and cold. The plant colors in autumn as temperatures fall, deepens through winter, flushes bronze on new spring growth, and settles to green through the heat of summer.
A plant in full sun in a cold winter goes deep crimson. The same plant in shade stays mid-green all year. If you want the color and are not getting it, the fix is more light, not more feed, and in practice that usually means moving the plant in autumn or removing whatever is shading it. Nothing you apply to the soil produces the red.
The opposite problem appears in hot climates: leaves in relentless afternoon sun with dry soil scorch brown at the edges rather than coloring cleanly. There, afternoon shade and a decent mulch give better foliage than an open position, and you accept a greener plant.
Winter browning on an exposed plant is a third and separate thing. Cold drying wind pulls moisture out of evergreen leaves faster than frozen ground can replace it, and the result looks dead. Leave it. Do not cut anything until new growth is clearly moving in late spring, because most of what looks finished recovers.
Deciding about the berries
This is the one genuinely consequential care decision, and it is worth making deliberately rather than by default. The plant flowers in early summer in loose white sprays, and the fruit that follows colors in autumn and holds on the canes right through winter, which is a large part of the plant's appeal.
The case for removing it is strong. Nandina berries contain cyanogenic compounds, and because they persist into late winter they are available exactly when other bird food has run out. Flocking birds that strip a plant in one visit, cedar waxwings in particular, have been killed by eating large quantities in a single feed. Separately, birds that eat the fruit and survive carry the seed into wild ground, and in parts of the southeastern United States the plant has established in woodland and is listed as invasive. Both problems are solved by cutting the fruit off.
Do it once the berries have colored but before they soften, cutting each cluster back to the first leaf below it. On a mature clump it takes five minutes. The plant is entirely unharmed, and you are trading winter color for a hazard removed.
If you garden somewhere the plant is not invasive and you decide to keep the fruit for the display, that is a defensible choice, but keep it a decision rather than an oversight, and be aware of which birds visit your garden in winter.
Keep three dates each year: when the plant flowered, when the berries colored, and when you cut the fruit off. Berry removal has a window of about ten days between coloring and the birds starting to feed, and last year's dates are far more use than an estimate.
The rest of the year
Through spring, watch the new canes coming up at the base and count them, because a clump producing four or five new canes a year is in good order and one producing none needs more light or less competition. Pull any weeds and grass out of the middle of the clump while you can still reach in.
Through summer, do very little. Water new plants weekly, check containers daily, and pull off any individual leaves that have scorched or spotted. Do not prune in late summer or early autumn, because growth pushed then goes into winter soft.
Through autumn and winter, deal with the fruit, enjoy the color, and leave winter damage strictly alone until late spring. The main annual job, the renewal cut that takes a third of the canes to the ground, belongs in late winter while the plant is dormant and the cane structure is easy to read. Everything else about this plant is watching.