Hibiscus Shrivel After Heavy Pruning: Root Rot or Nematodes?
Diagnosis: Root System Failure
Sudden shriveling of new blooms and leaves on multiple hibiscus after severe pruning indicates the roots cannot supply water fast enough. Three main causes:
Cause
Diagnostic Clues
Confirmation
Bacterial/fungal root rot
Foul smell from root zone; brown/black mushy roots
Dig down 6–8 inches; smell & inspect roots
Root-knot nematodes
Swollen galls on roots; general decline
Unearth roots; look for bead-like knots
Other nematodes
No visible galls; stunted roots
Soil assay by nematology lab
Immediate Actions
Check roots now: Dig carefully at drip line. Smell for rot; look for galls.
If rot: Remove affected roots; drench with copper fungicide or Trichoderma biofungicide. Improve drainage.
If nematodes: Solarize soil (clear plastic, 4–6 weeks summer heat), or apply beneficial nematodes (Steinernema).
Reduce canopy: Prune top growth to match reduced root capacity.
Prevention
Never prune more than 1/3 of canopy at once. Mulch heavily to moderate soil temperature. Use compost to boost beneficial microbes.
Three plants affected simultaneously strongly points to a shared soil/root issue. Investigate the roots this week.
