Work compost or other organic matter into the bed before planting. Apply a 2- to 3-inch layer of compost on the bed and till it into the top 6 to 8 inches of soil. Use potting soils rich in organic matter for container-grown impatiens.
Water impatiens once weekly or when the top 1 inch of soil begins to feel dry to the touch. Water until the top 6 inches of soil feels moist. In containers, water once daily until the excess moisture begins to drain from the bottom of the pot.
Mulch around bedding plants with a 2-inch layer of organic mulch, such as bark or wood chips. Mulch preserves soil moisture, keeps the roots cool and prevents weed growth.
Feed impatiens once monthly with a soluble 13-13-13 fertilizer or other balanced fertilizer. Follow label instructions for exact application rate for the fertilizer you are using. Fertilize container-grown impatiens every two weeks with a soluble flowering plant food.
Pinch back impatiens after planting to encourage full, bushy growth. Pinch off the top 1 inch of each growing stem, as this encourages lateral branching and more flowers. Pinch plants a second time in mid-summer if they become leggy or stop blooming.