Think outside The Window BOX

Photographs & window Boxes By Helena - The Urban Garden Companion

thriller. filler. spiller.

Window boxes are displays, they present a window, mark a season, define a space and when done right provide inspiration for the viewer and admiration for the maker. From a Parisian courtyard to a NYC 5th ave Brownstone, window boxes are best served spectacular!

There are so many different formats that produce a show stopping  window box.  My favorite is the - Thriller. Filler. Spiller. It’s a super easy technique with a few variations that you can use over and over again, taking the guess work out of designing stunning window boxes in any season. Here’s a breakdown of the technique. 

Thriller - is the show stopper plant and vertical accent of the box. 

Filler -is the meaty middle and horizontal angle of the box. 

Spiller - is the cascading plant draping over the sides of the box. 


Just as in good landscaping the three different height levels of the - Thriller. Filler. Spiller. creates layers giving your window box a professional polished finish. Sky’s the limit with the different plant combinations you can use and each season brings new  possibilities. Stick to your taste of colors, textures and shapes and do err on the side of imagination!

Variegated Miniature Boxwood, Ornamental Chilies, Dusty Miller, Coleus, Creeping Jenny


When planting boxes in mid to late spring, ensure to leave enough room for this busy seasonal growth period. The long summer days and balmy nights, give your plants everything they need to grow. Fill your boxes when planting but don’t over crowd them with plants.

Tuberose Begonias, Diamond Frost Euphorbia, Blue Lobelia, Diacondra Silver Falls

Planting Tips

If working with hard to reach boxes, use an evergreen Thriller and Spiller and just switch out the Filler each season to keeping the box current. I love working with miniature evergreen trees, there are so many different types to choose from in all colors, shapes and sizes. I like to use these as my middle feature plant the - Thriller. Maintain boxes with liquid plant food once a fortnight using a watering can with a rose cap ( a cap with small holes) and make sure to foliar feed as well as feeding the soil. When working with a 24 inch rectangular box , use up to two Fillers. When using a 28 inch or longer box, you can use up to four different Fillers within the standard format.  There are loads of variations of the standard format, when you get comfortable with working with the technique, you can use two different Spillers on the ends of the box and in the middle with the -Thriller feature plant. You could also use two different Thrillers. For now, stick to the standard - Thriller , Filler , Spiller, format.

Black Dragon Japonica Miniature Cedar Tree, Winterberry, Heather, Blue Pacific Shore Juniper

Blue Grass Fescue, Dusty Miller, Pansy

Foraged Window Boxes

Stores had closed for a few months in early 2020, and I find buying established plants online to be a bit tricky. I like to have eyes on them before buying, to get all the shape and sizes right. As the garden centers closed during this time, I foraged through my back yard to make an early spring window box. I had overwintered some plants that I used, and others were growing in the ground in the garden. I foraged the cracks and crevices of my backyard, where plants had self sown. Others, were divisions that had lived through the mild winter of 2019. Perennials such as Creeping Jenny and Pansies, can be carefully divided up in the spring to use in other boxes. Here, I’ve switched the format so that the Filler, is on the ends of the box and the Spiller, is in the middle of the box just in front of the Thriller. An example of a variation of the technique.

       Window Boxes Classic Seasonal bloom combinations

spring - gardens

Begonia, Spike, Ivy, lobelia

Hibiscus, Fern, Spike, Calibrachoa

Lantana, Spike, English Ivy, Portulaca


Snap Dragon, English Ivy, Bacopa, Calibrachoa

Fresh Ideas for Window Boxes

Here’s a few plant ideas to work with in each season. 

The plants are listed in the order of  Thriller, Filler, Spiller.

Early Spring - Hellebore, Hyacinth, Ivy

Late Spring  -Angelonia, Calibrachoa, Vinca Vine

Summer - Guara, Wave Petunia, Creeping Jenny

Fall - Golden Rod, Caryopteris,  Needle Point Ivy

Winter - False Holly, Winterberry, Blue Pacific Juniper

Plant reference photos left to right