Troubleshooting
Japanese Blood Grass problems — and how to fix them
Japanese Blood Grass (Imperata cylindrica 'Rubra') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Green reversion
Plain green shoots can appear and grow more vigorously than the red form; remove them promptly at the base, as they revert toward the invasive wild type.
Invasive parent species
The wild species (cogongrass) is a serious noxious weed banned in parts of the US; only the ornamental 'Rubra' is grown, but plant it cautiously and check local regulations.
Weak red colour
Dull or mostly green foliage usually means too much shade; move to full sun for the brightest blood-red tones.
Slow spring emergence
Blood grass is late to break dormancy and dies back in winter; do not assume it has died, and cut back old foliage in late winter.
Prevent japanese blood grass problems before they start
Most japanese blood grass issues are care-mismatch, not bad luck. Dial in the basics:
Looking for japanese blood grass in general rather than its problems? Read the full japanese blood grass care guide — light, water, soil and feeding.
Japanese Blood Grass problems — FAQ
Why is my japanese blood grass green reversion?
Plain green shoots can appear and grow more vigorously than the red form; remove them promptly at the base, as they revert toward the invasive wild type.
Why is my japanese blood grass invasive parent species?
The wild species (cogongrass) is a serious noxious weed banned in parts of the US; only the ornamental 'Rubra' is grown, but plant it cautiously and check local regulations.
Why is my japanese blood grass weak red colour?
Dull or mostly green foliage usually means too much shade; move to full sun for the brightest blood-red tones.
Why is my japanese blood grass slow spring emergence?
Blood grass is late to break dormancy and dies back in winter; do not assume it has died, and cut back old foliage in late winter.