Choose black pearl peppers as an unexpected windowsill plant. Black pearl peppers grow to around 2 feet in height with a spread of around 18 inches. Black pearl peppers prefer well-drained, organic-rich soil and full sun. They will grow in shadier locales but have a tendency to get leggy. Healthy peppers are bushy, compact and loaded with small, purple fruits that mature to red. Peppers are edible at both purple and red stages.
Angeline sedum is low growing, grows quickly and makes an attractive cascade plant in containers. Its foliage consists of tightly packed succulent leaves in shades of green, yellow orange and bronze. Angeline blossoms are yellow and abundant. This plant has excellent drought tolerance. It achieves the best color when planted in full sun.
Grow portulaca for its multitude of colors. It blossoms with both single and double flowers. Portulaca's succulent leaves make an attractive foil for other, taller plants. Treat portulaca as an annual or overwinter indoors in a sunny window. Although drought tolerant, portulaca appreciates regular watering. Pinching faded blossoms will encourage another flush of blooms and a bushier habit.
Choose from a variety of miniature ivies to add height to your window boxes. Ivy prefers moist, well-drained soils. Try training ivy up a miniature trellis on the sides of your window box. Ivy comes in variegated and solid forms with a multitude of leaf shapes. Water your ivy regularly for the best growth and appearance.