How to Plant a Perennial Window Box

Care for you window box flowers so they thrive.

Care for you window box flowers so they thrive.

Perhaps nothing speaks quaint like a couple window boxes filled with beautiful, flowering plants. They also add a splash of pizzazz to an otherwise boring home. If gardening isn't your thing or if money is an issue, perennials are the perfect choice for window boxes. In the right climate and environment, they can survive through the winter and grow back the following spring. In climates with light frosts, your perennial choices may seem endless.


Drill two or three 1/4-inch drainage holes in the bottom of your window box if it doesn't already have them. If your window box is made from wire and lined with moss or coco fiber, it drains well already.


Choose plants that tolerate the amount of sunlight the box will receive. The southern side of a home is the sunniest and the northern side is the shadiest. The western and eastern sides of the home receive a moderate amount of sunlight; however, the western side receives afternoon sun, which is hotter. Consider other factors such as trees and other buildings that may provide additional shade.


Select perennials that are more cold hardy than your climate, since container-grown plants are more susceptible to winter temperatures than garden-grown plants. Alternatively, you can take down a window box and store it in a garage or another protected location for the winter to preserve perennial plants until spring.


Water your plants one day before transplanting them. If the window box contains moss, soak it in water a few minutes before filling it with soil.


Fill the window box with a lightweight, high-quality potting soil, leaving about 1 inch of space between the rim and the soil. The extra space helps prevent the soil from spilling out during heavy rain and winds.


Plant the plants so the root balls are slightly higher than the soil. They will settle after a couple waterings. Grow the taller and upright plants in the back of the box, closest to the window. Grow the trailing and shorter plants on the sides and front. Container plants can be planted much closer together than the recommended spacing.


Water plants well with enough water that it starts to drip out the bottom. If the potting mix did not contain fertilizer, add a complete, balanced fertilizer -- 10-10-10 for instance -- just before watering. Apply the amount of fertilizer specified on the label.

Things You Will Need

  • Drill
  • 1/4-inch drill bit
  • Potting soil
  • Fertilizer


  • Trailing or cascading plants work well in window boxes that are above eye level. Million bells (Calibrachoa), dichondra and ivy geraniums (Pelargonium peltatum) may be perfect for your window box.
  • Herbs, such as mint (Mentha), oregano (Origanum vulgare) and thyme (thymus), can be conveniently planted in a kitchen window box.

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