Optimal Conditions
When a patch has been overwatered and mulched too deeply, particularly when growing in heavy soils.
Signature
Stems turning to a dark colour and then beginning to rot.
Prevention
Get your watering practices right, particularly when you have boggy, water-holding soil, which will make plants more prone to the condition. When mulching, leave a clear area around the stem.
Coping
It’s almost impossible to reverse the damage of stem rot and you will lose those plants affected.
Eradicating
Mulch to no deeper than 5 cm (2 in) and allow the stems to breathe.