Proper care of your flowering houseplants ensures healthy growth with the maximum blooming period. The basic requirements for houseplants include optimal soil conditions, temperature, water and light. When these requirements are met the plant is able to reach its full potential, even when growing indoors. Perennials must be carefully tended to or they won't store the necessary nutrients to flower again, while with annuals the only concern is for a single flowering season.
Check the containers for proper drainage. Remove any decorative foil coverings as these tend to hold water that may lead to soggy soil conditions or disease. Check the drainage holes and make sure they aren't blocked by roots or compacted soil. Push a pencil 1 inch into any blocked drainage holes to clear them.
Water, of course, is essential to a plant's well-being. To check a plant's moisture level, stick your finger into the soil to a 2-inch depth. If the soil feels barely damp, add water until it comes out through the bottom drainage holes. Dump out the water from the drip tray once it stops draining.
Most flowering plants need full sun while the foliage is actively growing. Place them in a south-facing window for at least 8 hours daily or under fluorescent lights for 12 to 16 hours. Once flower buds begin to open, move plants to an area of bright, diffused light as too much direct sun may result in premature petal drop.
Keep flowering plants in a 70 to 75 F room during the day and move them to a 55 to 60 F room at night. High temperatures lead to flower drop while lower nighttime temperatures help blooms last longer.
Place plants away from drafts or air vents. Seal windows well if plants are displayed nearby and close registers so air conditioning or blasts of heated air don't dry out the plant and cause petal drop.
Fertilize with a balanced liquid houseplant food once buds begin forming. Fertilize with a half-strength dilution every two weeks until the plants begin to enter dormancy in fall or---for annuals---until the flowering period ends.