Bougainvilleas like to grow in full sun for best blooming (but can tolerate some shade). Their ideal soil PH is 5.5 to 6.0.
They like to be moderately watered. Too much water is probably one of the chief reasons for lack of bloom. Be sure that the soil is a well draining soil (sand rather than clay). You may need to adjust you irrigation so that they receive less water than the sod, etc.
When fertilizing, look for low nitrogen mixes. You can use a balanced mix like a 6-6-6 or an 8-8-8. There are blooming fertilizaers such as a 2-10-10 that are good. (Our current favorite here at the nursery is a Helena 6-8-14 mix.) Bougies sometimes enjoy a feeding of minors such as ironite or milorganite.
We suggest that you consider planting Bougainvilleas (especially 7 gallon and 15 gallon) 'in the pot'. Leave the plant in the container and cut big holes in the side of the pot. This proves protection for the delicate root system and allows the roots to escape as the plant grows. For aesthetics you may find that you also need to remove the top lip of the pot.
Our customers have found this to be beneficial. It protects the plants from transplant shock initially. In the long run it seems to cause the plant to bloom better by 'stressing' it (by having the root ball somewhat constricted).
The most common pest problem is the Bougainvillea Worm during the warmer months. Insecticides will kill them, but you may need to treat more than once. We rotate between applications of Sevin and the Bacillis Thuringensis. The safest for the homeowner are the B. T's such as Dipel, Zentari or Thuricide. Spraying in the evening is best, since the worms feed at night. Do not use Disyston granules as they will stop the plant from blooming.