It prefers a good, deep watering every three or four weeks to frequent shallow waterings. Give a bougainvillea too much water and it can get fungal diseases and root rot. Bougainvillea blooms better when kept on the dry side. Too much water will give you lots of green growth and fewer flowers.
To ensure abundant flowering plants and good overall health of plants, use a balanced, slow-release fertilizer containing nitrogen, phosphorus, and potassium (N-P-K) in equal ratios, such as 5-5-5 or 10-10-10, and don't forget this when repotting.
Bougainvillea needs at least 6 hours of full sun a day to flower profusely and look its best. This plant also loves the heat. Not enough sun = not enough color.
Bougainvillea is a relatively hardy plant, able to withstand a range of temperatures, from tropical highs of 80 degrees Fahrenheit and above, all the way down to 40 degrees Fahrenheit. That being said, for your bougainvillea to truly thrive indoors, maintain temperatures around 60 to 70 degrees Fahrenheit.
Bougainvillea performs well in a relatively small container where its roots are slightly restricted. When the plant is large enough for repotting, move it to a container only one size larger. Use a regular potting soil without a high level of peat moss; too much peat retains moisture and may result in root.