From Divination for Beginners, by Scott Cunningham

Plants have long been called upon to provide glimpses of the future. This form of divination, termed botanomancy, uses plants in innumerable ways: they’re placed beneath the pillow to create prophetic dreams; are sown and observed as they grow; are used as pendulums; and are tossed into water, air, or fire. Plants seen unexpectedly are responsible for a wide range of omens, especially those relating to the weather. Some plants have quite curious uses.

The rationale for the use of plants in divination is clear: they are (or were) living things, they have closer ties to human life than most other tools of prognostication; thus, they may possess the ability to more accurately predict our lives. Additionally, certain types of plants have long been recognized as possessing specific nonphysical energies, and some forms of divination capitalize upon this phenomenon. I hasten to add, however, that the belief in such energies isn’t necessary to the practice of botanomancy. The following technique is within the realm of divination, not magic…

A General Plant Divination
Fill five flower pots with the same kind of dirt. Plant in each pot a seed of the same type of flower, on the same day and at the same time. Ensure that they have the same exposure to sunlight (if applicable). For best results, do this on the day of the full moon.

On a small piece of tape, write an expected or hoped-for future and apply this to the side of one pot. Continue until all five pots have been designated with five different futures. (Small signs attached to sticks or twigs may also be used, thrust into the earth near the pot’s side.) Water as usual. The seed that first germinates determines the event that will most likely occur in the near future.