We've received several emails now asking whether RD-20 is safe to use on orchid plants, so I thought I'd post something about it here. RD-20 is marketed commercially as a bactericide / fungicide for orchids and, when used as directed, does a fine job.

HOWEVER: Even when dilluted and used as directed, RD-20 will burn many orchid blooms, causing them to turn brown where the solution has contacted the flower. Use RD-20 ONLY on your non-blooming orchid plants and be sure not to mix the solution any stronger than 1 tablespoon per gallon of water.

If you don't mind a little white haze residue on your orchid's leaves, Daconil fungicide, also readily available, does a fine job as well and doesn't burn the blooms. And if you're having problems with bacterial infections, plain old Listerine mouthwash will work wonders.