Give Your Home A Face-Lift With This Easy Window Box Project

Spruce up your windowsill with a lovely container garden.

May 12, 2016
window box of flowers
1000 Words/Shutterstock

Choosing the Right Container

Wood, plastic, copper, iron, tin, ceramic, terra-cotta, stone, wire, and fiberglass window boxes are all available. If your windows are in the sun all day, avoid a solid metal or darkly colored box, because they can heat up and toast plant roots. If you choose terra-cotta, be sure to immerse the boxes completely in water for a half hour before planting so that the clay doesn't absorb all the water meant for the plants.

A standard size window box is about 3 feet long—but consider the proportion of your windows before buying a box. Don't get a window box less than 4 inches wide because it won't look lush and will require constant watering. A window box should be about 25 percent of the height of the window or 20 percent if the window is very tall. Make sure the box has drainage holes, each about ½ inch in diameter, spaced about 6 inches apart. If it doesn't have any, you'll need to drill some. Cover the holes with screening or coffee filters to hold in the soil.


How to make a window box
Dana Gallagher

Related: The Absolute Easiest Herbs To Grow Indoors

Designing with Plants

If you're unsure how to combine plants attractively, follow this easy formula from the late Kathy Pufahl, horticulturist and owner of Beds and Borders nursery. Pufahl suggests picking one type of plant that grows up like grasses, spiky plants, geraniums, or other flowers on long, straight stems; one that trails down like ivy, sweet potato vine, thyme, lobelia; and one bushy type to fill in the middle like impatiens, petunia, dwarf ornamental pepper. Like other types of container gardening, if you have room, you can add a fourth type as filler, one that contrasts in color, texture, or foliage size with the others in the box.

How to make a window box
Dana Gallagher

Planting the Window Box

The best Soil Recipe For Window Boxes is usually a mix of peat or coir, perlite, and vermiculite. Provide some nutrients and help retain moisture by adding screened compost—it can be up to 20 percent of the mix. Moisten with warm water before planting and set the plants into the mix to the same depth they were in their containers. Firm them in and water again. Allow about an inch of space between the soil and the top of the box.


Related: 10 Unusual Spring Flowers

Keep Them Looking Good

Knowing How And When To Water your plants is essential for cultivating a healthy window box. If it sits in direct sun for much of the day, you may need to water both morning and evening. Water until it runs out of the drainage holes and don't assume that because it has rained that your plants have enough moisture. If your plants droop in the sunlight but recover in the shade or after sundown, they need more water.

Try not to let the soil completely dry out, especially if you use a soilless peat-based mix. Once peat dries, it no longer absorbs water but actually repels it, becoming almost impossible to rewet. If the peat does dry out, try this remedy from John Begeman, agriculture and natural resources agent at the University of Arizona: Add a few drops of liquid dishwashing detergent to a quart of water and then water slowly with this solution. The soap breaks the barrier to the soil and allows the water to be absorbed. The results should last a long time, so you shouldn't need to use the soap solution more than once or twice in a season.

Mulching the soil in a window box helps hold moisture in and gives a finished look to the box. Whatever you use—cocoa shells, finely shredded bark, or moss—be sure to thoroughly water the plants before adding the mulch or it could act as a barrier to the water. Periodically check to be sure that water is getting through to the soil and isn't running off the top of the mulch. 


Soil mixes don't provide enough nutrients for the plants to thrive the entire season, and whatever nutrients there are can wash out of the drainage holes when you water your plants. So to keep your plants healthy and growing, use organic fertilizer every two weeks.

Dead and decaying flowers, stems, and leaves can be sources of fungal growth, so be sure to pinch them off when you see them. Regular deadheading keeps annuals flowering instead of going to seed, and keeps plants looking their best.

Related: 20 Reasons To Start A Garden

How to make a window box
Dana Gallagher

Great Window Box Plants

Dwarf sunflower 
Fan flower
Million bells 
Yubi Hybrids

Black Mondo grass
Cordyline indivisa
Golden creeping Jenny
Licorice plant
Lotus vine
Ornamental kale
Sweet potato vine
Trailing coleus varieties 


Cherry tomatoes
Swiss chard