Nicolette Goff is a watercolourist, writer, and dedicated gardener. Her books, articles, and paintings reveal her love of nature.
Cascading Flowers, Greenery, and Herbs for Window Box Gardens
Window box plantings can add color and charm to your home, whether you're in an apartment, a suburban ranch-style house, or a country farmhouse. Filled with bright flowers and cascading greenery, they add a cheerful touch, enjoyable from both outside and inside.
Or perhaps you'd just like to have some herbs within reach, just outside your kitchen window, rather than somewhere out in the garden. Window boxes aren't just for flowers!
Types of Window Boxes
You can make (or buy) window boxes of various materials—the old standby of wood, or fiberglass, plastic, or terra cotta window boxes. There are elegant styles and country casual styles, some in color, others in metal.
You're probably better off avoiding metal boxes if you're placing it in a sunny area. The metal will conduct heat readily, causing over-heating of the roots.
You will even find some that are just a light metal framework, with a cocofiber liner. Other boxes are not window, but railing-mounted boxes. These add a festive touch of color to any balcony.
Choosing and Installing the Window Box
The deeper the box, the better for healthy root growth. It should also be at least 8 - 10 inches wide, and a minimum of 6 inches deep. Too shallow or narrow a box will dry out quickly, but too large a box will be too heavy to attach securely to the house, and will look ungainly.
Make sure your box has sufficient drain holes. Waterlogged roots will kill your plants. Line the bottom of the box with a piece of screen to keep the soil from washing out, or put in a layer of sphagnum moss as a liner. The moss will also help keep the box from drying out. If you're opting for wood, and want your box to last for several seasons, a thin metal liner is a must.
Mount the box so the top is just under the windowsill, using a spacer for air circulation between the box and the house exterior wall. Use galvanized wood screws every 16 inches to hold it securely. If your house is brick, drill holes in the mortar and drive in a lug, then screw through the back of the box into the lug.
Another method is to use two or three-angle bracket supports mounted to the wall, with the box attached to them. If you are unable (or not allowed) to attach your window box to the house wall, you may find free-standing metal plant supports in your garden shop, that sits on the soil or balcony beneath your window, and the window box can be placed on that.
Best Soil for Window Boxes
Once the box is in place, put a layer of drain rock, broken pottery, or chunks of styrofoam in the bottom to ensure good drainage. Using styrofoam will not only make the box lighter, but it's a good re-use of some of that packing material we all seem to collect.
Then, fill it with a balanced planting mix containing compost, sharp sand, topsoil and vermiculite or perlite. It's possible to find soils specifically for window boxes or containers that have water-retaining properties, or you can buy the crystals and add them to your soil mix.
Don't use regular garden soil, as it will pack too densely and suffocate the plant roots.
Summer Window Boxes Contest
Deciding What to Plant
The old stand-bys of geraniums and petunias are colorful, with abundant blooms, but don't limit yourself to them.
Try plants with different growing habits—some bushy, some trailing, and others that grow upright. Look for different textures—frothy blossoms of alyssum, waxy smooth begonia leaves, or spiky tall dracena. Choose plants of varying heights, but ones that grow less than 16 inches tall are best.
Think about the color of your house, and the surrounding landscape, and choose plants with blossom colors that work with what's already there. Then, think about the greenery. Go for different shades of greenery—and even add some colorful foliage plants like coleus for a bit of zing.
Before you choose plants for your window box, take a look at the area where you plan to place the container.
Is it in full sun all day long or does it get partial or even full shade?
Is it under an overhang or is it in an area that allows it to take advantage of the rainfall?
Once you know what the growing environment will be like, you will be able to choose the best plants for window boxes in your location.
Full Sun Window Box Plants
There are several options for full sun window boxes depending on what style and type of plants you prefer. For a window box in the sun, try plants from the following categories:
Upright plants: Dusty miller, geraniums, celosia, nicotania, scarlet sage, calendula, marigolds, pinks, coleus, wax begonia, impatiens, dahlias, dianthus, gerbera daisies, miniature roses, basil.
Bushy plants: Ageratum, artemisias, california poppy, pansy, alyssum, thyme, viola, dwarf zinnia, browallia, lobelia, small leaf basil.
Sprawling and trailing plants: Lantana, nasturtium, oregano, petunia, verbena, forget-me-not. english ivy, periwinkle, asparagus fern, euonymus, trailing rosemary, sweet potato vine, nastursium, bacopa.
Partial or Full Shade Window Box Plants
Likewise, depending on your preferred look, there are several options for planting in a window box in semi-shade or shade:
Upright plants or bushy plants: Caladiums, coleus, ferns, rex begonias, tuberous begonias, hosta, astilbe, lemon balm, snapdragon, browallia, impatiens, pansy, parsley, sweet alyssum.
Trailing plants: English Ivy, periwinkle, strawberry begonia, fuchsias, variegated vinca, wandering jew, trumpet vine.
Window Box Planting and Growing Tips
- Strive for an effect of fullness as you plant. Put the plants closer together than you would in the garden, and put taller ones at the back. Sprawling ones or vines will tumble over the edge of the box, softening the effect.
- Water them well, and continue watering every second or third day, even in rainy weather. After the first two weeks, you should feed them bi-weekly with diluted liquid fertilizer.
- Mulch the window boxes to help retain moisture, and to keep the flowers looking fresh.
- Deadhead the flowers regularly, and pinch back the growing tips so the plants get bushier, rather than leggy.
- Two or three times in the season, snip the plants back into shape. Some will grow faster than others, so you need to keep the plantings balanced. Do your pruning in the morning or evening rather than in the heat of the day.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Jill Spencer from United States on October 28, 2011:
Beautiful hub with lots of good info and great pics. Thanks!
Paul Cronin from Winnipeg on August 17, 2011:
i really love the metal frame baskets, really adds a nice touch. Great pics, really enhances your home. Thanks for sharing these great ideas!
Fluffy77 from Enterprise, OR on April 13, 2011:
Love the flower boxes, I have a cousin who made us some. They are so beautiful to have around really. Nice looking ones here and good ideas for there placements too thanks.