A high glucose content (around 40%) will cause the honey to crystallize in 2 or 3 days, like osr and dandelion. A high fructose content (more than 42%) will allow the honey to stay liquid for several years, as is the case with acacia honey and the honeydews.Most honey is somewhere in between and crystallizes in a few weeks.
The two other parameters for speed of crystallisation are humidity and temperature.For crystals to form, the glucose molecules must meet up with "seeding nodules" and stick to them.Too much water hinders this, and so crystallisation is slower.On the other hand, if there is not enough water,the honey will be too viscous for the glucose molecules to move and so a "dry" honey will no longer crystallize. Temperature has a similar effect: a low temperature favours a higher viscosity (that of a honey at 20° is four times higher than at 32°. A high temperature causes the glucose molecules to vibrate and prevents them from forming crystals.Above 30° the crystallisation stops which is why honey stays liquid in the parts of the hive that are occupied by the bees.

The above is a rough translation of an article by Etienne Bruneau