What is it and how to avoid it

Grey mold or botrytis cinerea is a bacterial root disease that will develop on tulip roots and attack the bulb itself.  Grey mold will then attack the stem and plant during the greenhouse phase.


  • Grey mold can be seen in the cooler during the winter months
  • Grey puffy or fuzzy mold growing on drainage holes
  • Slimy glazy roots in the bottom of the pot


Caused by:

  • Long extended rooting time at 48 degrees causing excessive root formation at the bottom of the pot
  • Ethylene gas build-up - Make sure your bulbs are stored in a well ventilated area or room. Your bulbs need to breath, otherwise your flowers may abort or dry up when in the greenhouse phase
  • Too clean or sterile potting mix - The growing medium used by most growers is a straight artificial growing mix. These steamed and sterilized growing mixes are too clean. Tulips need a mix of sand and good quality top soil mix capable of fighting infection


Take These Steps to AVOID GREY MOLD:

  • Always use new pots
  • Use the proper growing mix as described above
  • Root tulips until they just hit the bottom of the pot 
  • Follow temperature schedule as described in the Cooler Instructions