How to Make Window Boxes and Floral Arrangements

Photographs & window Boxes By Helena - The Urban Garden Companion

Window boxes made with the thriller.filler.spiller. 

Window boxes present a window, mark a season, define 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 creating 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. 

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


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


When engaged in the art of creating seasonal display boxes in the spring and summer, consider how much room you'll need to leave between plants for growth. Do fill your boxes when planting however, don't leave huge gaps between the plants while also not cramming in the plants. When planting boxes in the fall and early winter, ensure that your arrangements are robust but not jammed in. During the colder months leave less room for growth.

window boxes - 2
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 switch out the Filler each season to keep 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 Thriller.

window Boxes & Dimensions

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.

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.


window boxes 2
Miniature Arborvitae, Winter Berry, Cypress, Vinca Vine Seasonal White Sticks and Berries
window boxes - 2
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.

        Classic Seasonal bloom combinations window boxes