Gadenin日本語Get the appBrowned and bleached leaves: telling the causes apart
Damaged foliage is the complaint that brings people to this plant, and there are only four realistic causes: direct sun, dry wind, root dryness and frost. They produce similar-looking brown leaves, but they differ in where the damage sits, how fast it appears and what the weather was doing beforehand, and those three clues separate them reliably.
Sun scorch appears gradually over a warm bright spell, is worst on the side of the plant facing the light, and tends to bleach the leaf to a pale yellow-green before the tissue browns. It is common on plants sited under deciduous trees, where a position that is deep shade in summer receives hours of direct sun in early spring before the canopy closes.
Wind burn appears all at once, usually after a cold windy few days, sits on the exposed side of the plant, and browns the margins and tips while the middle of the leaf stays green. Root dryness browns the tips of leaves all over the plant at the same time and is accompanied by a limp look and dry soil 2 inches (5 cm) down. Frost damage blackens whole shoot tips rather than leaf edges and shows within a day or two of a hard freeze.
None of the four is treatable on the leaf itself. Remove the worst affected leaves in spring by cutting the stalk close to the cane, fix the position or the watering, and let new growth cover the gap.
| Sign | Likely cause | Action |
|---|---|---|
| Pale bleached leaves on one side, warm bright spell | Sun scorch | Shade the plant or move it in autumn or spring |
| Brown crisp margins on the windward side, after cold wind | Wind burn | Put a mesh screen on the prevailing side for winter |
| Brown tips all over the plant, soil dry at 2 inches (5 cm) | Root dryness | Soak thoroughly, mulch to 2 inches (5 cm), check monthly |
| Whole shoot tips blackened within days of a freeze | Frost damage | Leave until spring, then cut back to live green wood |
| Sticky leaves with black film on the upper surfaces | Scale or mealybug above, sooty mold growing on honeydew | Find the insects on the stems and undersides, then treat |
| Fine pale stippling and webbing, worst under cover | Spider mite in dry air | Raise humidity, wash the foliage, isolate the plant |
| Small round brown spots with darker edges on old leaves | Leaf spot fungus on foliage kept wet in still air | Remove affected leaves, water at the base only |
| Sudden wilt with no recovery after watering | Root rot from waterlogged soil | Lift and inspect the roots, repot into open mix |
Scale, mealybug and the sticky-leaf problem
The pests that actually matter on this plant are the sap-suckers that like still, shaded, sheltered air, which is exactly the environment it is grown in. Scale insects sit as small brown or fawn limpets along the canes and on the leaf midribs, mealybugs as white cottony smudges in the leaf joints, and both are usually noticed indirectly, through the sticky honeydew they drop and the black sooty mold that grows on it.
- Check the places they hide, not the places you look Turn the plant or crouch down and examine the undersides of the leaves, the leaf joints and the shaded inner canes near the base. Scale is almost never on the top surfaces where the eye naturally goes.
- Rub off a light infestation by hand A cotton bud dipped in dilute alcohol lifts individual scale and mealybug cleanly. On a plant of this size a thorough hand clean takes a quarter of an hour and is more effective than spraying.
- Treat a heavy infestation when the crawlers are moving Adult scale is armoured and resists sprays. Treat in late spring when the young crawlers are active, using horticultural oil or insecticidal soap, and cover the undersides and stems thoroughly rather than misting the top.
- Wash the sooty mold off afterwards Sooty mold does not attack the plant but it blocks light from the leaf. Once the insects are gone, wipe the affected leaves with a damp cloth, supporting each leaf from underneath as you work.
- Cut out any cane that is heavily encrusted A cane carrying dense scale along its whole length is easier to remove at the base than to clean, and taking it out improves air movement through the plant at the same time.
Poor or dropped berries
A berry failure is worth diagnosing carefully, because the plant is usually behaving correctly and something in the position is at fault. Work through it in order: did the flower spikes form at all, did they set fruit, did the fruit swell, and did it color and hold.
No flower spikes at all points to light or age. A very young plant may take a season or two to settle, and a plant in genuinely dark shade with no diffuse light at all can grow perfectly well and fruit poorly. Spikes that form but drop before swelling usually indicate a check at the root, most often a dry fortnight while the plant was setting fruit.
Berries that swell but shrivel before turning red are nearly always dryness, sometimes wind. Berries that color but stay dull orange rather than deepening to scarlet, and fade quickly, are getting too much direct light. Berries that vanish overnight have been eaten by birds, which is common and unavoidable in an open garden; a plant grown in a pot on a sheltered porch usually keeps its crop far longer.
One more possibility deserves ruling out before you change anything: the previous spring's pruning. Cutting or tipping canes after the coldest part of winter removes the shoot tips that would have carried the spikes, and a plant sheared over in spring will simply not fruit that year regardless of how good its position is.
Root problems and sudden collapse
A plant that wilts and does not recover after a thorough watering has a root problem, and there are only two common ones. Waterlogging kills the roots by suffocation and shows up as dark, soft, foul-smelling roots when the plant is lifted. Root dryness sustained over weeks kills the fine feeding roots and leaves them dry and brittle. Both produce a limp plant, which is why lifting it is the only way to be sure.
For a waterlogged plant in a container, tip it out, cut away any black soft roots, and repot into fresh open mix with plenty of bark or grit, into a pot no larger than the one it came from. Keep it barely damp and in deep shade until new growth appears. For a plant in the ground, the fix is drainage: lift it, improve the soil, and replant slightly proud of the surrounding level.
Where a plant is repeatedly lost in the same position, stop replanting there. Sarcandra will not overcome a spot that combines heavy soil with standing winter water, and no amount of soil improvement in a single hole compensates for ground that drains into it from all sides.
Write down the date and description of each problem as it appears, along with what the weather had done in the previous week. Sun scorch, wind burn and drought damage look nearly identical on a leaf a month later, and the dated note is what lets you fix the actual cause next year instead of guessing.