I successfully propagate bougainvilleas in water. but there are some tips. 1: choose cuttings that are almost hard to avoid being rot in water 2: put them in a small sized paper cup filled half by water. remember that wide opening of cups help evaporating water and keeping the appropriate humidity. 3: after 2 days when the water level decreases, add some dilute iron powder solution in the cup so the color changes almost red but you can see the button. 4: remember that the small white dots appear on the body of cuttings after 10 to 20 days, these are not roots but good signs of doing well. 5: wait until real roots emerge from the button of cuttings about 2 month or more after preparing the cuttings. wait another month or more until the roots become between 2 to 3 inches long. You will see that roots go around the button of the cup.New growth and fresh leaves are another signs of this final stage. 6: putt the rooted cuttings in a well draining clay pot and water thoroughly. 7: more important tips: a)best time for taking the cuttings is during or after flowering. b) best temperature for this method is about 22c. c)keep checking the water level inside cups and add water and iron solution when needed. d)to avoid fungus remove any leaves that fall inside the cup from cuttings asap. e)keep the cuttings away from direct sunlight, very little filtered sunlight is enough. f) keep the pots in the same place that you keep cuttings for several days and move them gradually to the full sun, except your cuttings wilt after potting due to changes in humidity and temperature. this was my 3-year-experience of propagating bougainvilleas, believe or not 10 times more successful than other methods like putting the cuttings inside potting mixture or even using rooting hormone. i sure hope this will help you. best wishes, god speed you...

I successfully propagate bougainvilleas in water, but there are some tips:

1. Choose cuttings that are almost hard (to avoid rotting in water).
2. Put them in a small size paper cup half filled with water; remember that wide opening of cups help evaporating water, so keep the appropriate humidity.
3. After 2 days when the water level decreases, add some dilute iron powder solution in the cup so the color changes to almost red but you can see the bottom
4. Remember that the small white dots appear on the body of cuttings after 10 to 20 days, these are not roots but good signs of doing well.
5. Wait until real roots emerge from the bottom of cuttings, about 2 months or more after preparing the cuttings. Wait another month or more until the roots become between 2 to 3 inches long. You will see that roots go around the bottom of the cup. New growth and fresh leaves are another signs of this final stage.
6. Put the rooted cuttings in a well draining clay pot and water thoroughly.
7. More important tips:

a) best time for taking the cuttings is during or after flowering. 

b) best temperature for this method is about 22°C (72°F). 

c) keep checking the water level inside cups and add water and iron solution when needed. 

d) to avoid fungus remove any leaves that fall inside the cup from cuttings as soon as possible. 

e) keep the cuttings away from direct sunlight, very little filtered sunlight is enough. 

f) keep the pots in the same place that you keep cuttings for several days and move them gradually to the full sun, otherwise your cuttings will wilt after potting due to changes in humidity and temperature.

This was my 3-year experience of propagating bougainvilleas. Believe or not, it is 10 times more successful than other methods like putting the cuttings inside potting mixture or even using rooting hormone and I sure hope this will help you.