Best Fillers & Herbs for Window Boxes

Best Fillers & Herbs for Window Boxes

Best Fillers & Herbs for Window Boxes

In a previous article about window boxes, we broached the topic of different flowers which were perfect for these little window gardens. These flowers have a number of different characteristics that set them apart from each other. However, most of them will need some type of filler to complete the look of your window planter box, adding a backdrop and some contrast for the flowers you will plant. In this article we hope to present you with some ideas for these fillers that will supplement your flowers and make your window box look even better. We have also included some thoughts on different herbs and small vegetables to plant for the more practical minded gardeners reading, many of these same herbs and vegetables can be found in our own window boxes here at home. So sit back, grab something to drink, make sure you're comfortable, and get ready to do some reading here as we do a quick crash course on all the extra guys that make planting in window boxes so much fun.

Fillers For the Window Box:

Sweet Potato Vine:

Also known as man-of-the-earth among other common aliases, this filler plant is a traditional and versatile plant for window box users. Unlike many of our delicate flowers that will only thrive in either direct sunlight or shade, the sweet potato vine finds itself at home in both. This durable plant will grow no matter the level of sunlight, though its color may vary depending on the sunlight, with darker greens being more prominent in the shade than in the sun. Keep these vines in moist soil and make sure to do some light pruning and this plant will fill the backdrop in any window box.

Dusty Miller:

Another favorite among gardeners, we won’t call this one by its common classification of silver ragwort, because the name Dusty Miller just sounds so much better. These plants create a different type of backdrop because like the scientific name suggests, it is a silvery white color. These plants enjoy the benefit of direct sunlight to not only grow the best, but also to maintain their silvery color, as a silvery green color will occur if they are planted in the shade. So throw these fun little guys in a sunny spot to create an ambiance unlike any others.

Asparagus Ferns:

A stunning green fern that thrives in indirect sunlight asparagus fern adds multiple bright tendrils. This 3-D appearance of the vines adds volume to your window box with ease and the need for indirect sunlight means they’ll pair relatively well with a number of flowers. But, this filler doesn’t come without a cost, they are toxic to both dogs and cats, so keep your furry friends away from them. The plant’s sap also has a mild irritant so handle with gloves and keep children away from any place you might plant this fern.

Water Hyssop

Also known as Bacopa, this is another fun creeping plant to act as a filler for your window box. The plant will spread across the base of the window box and some vines might spill down the sides of the box. Bacopa is a mostly green plant that has numerous white blooms throughout the plant to add a touch of color to your filler.


This plant could likely have been added to either of our lists about fillers or flowers, but we’re going to put it here because of its penchant for spreading throughout the area it's planted in and not growing very tall. Periwinkle thrives in direct or partial sunlight, making it a match for most flowers grown in window boxes. Periwinkle’s flowers also make for a great backdrop as they may have blooms in a variety of different colors.


Ivy is a popular filler plant for many gardeners in a number of different scenarios. This plant will work in a window box, thriving in most sunlight conditions and with moderate watering. Choose a type of ivy that fits your window and let the tenacious crawler fill out your window box, but make sure to occasionally prune the plant back.

Herbs and Vegetables:


A fragrant herb, mint has a number of different uses and can easily be planted in a window planter box. Mint will prefer early morning sunlight and shade in the afternoon heat, while also needing to be watered lightly, once or twice a day. This plant will thrive in these ideal conditions and it can be a highly invasive plant, making it perfect for the confines of a window box.


Small types of lettuce are an easy vegetable to cultivate in your window box and their lower tolerance to heat can make them a great filler in the spring and early fall months. Lettuce is particular when it comes to sunlight, so keep the delicate plants in partial sunlight and water regularly. With the right combination of soil and care, you should be able to harvest lettuce several times during its lifespan.


Another popular and healthy vegetable, spinach plants will grow in larger containers. If you plant the spinach from a seed starter you will need to place them at a depth of 6-12 inches. These plants prefer direct sunlight and will need to be watered and properly drained to produce fully grown plants. When harvesting your spinach make sure to take only the mature leaves, leaving younger leaves behind to promote growth.


Related to the onion family, chives are a relatively easy plant to grow and can add flavor and color to meals. Chives are planted in clumps and will grow in the presence of full or partial sunlight with regular watering. To take your planter up a notch, you can plant other onion types (green onions are a popular option) in the window box, though plants like spinach will not grow well in the same box as chives.


A popular cooking herb, thyme can be grown in window boxes with full sun exposure. Like many other herbs (sage, oregano, mint, etc.) thyme is a perennial, meaning the short woody stalks will produce year after year. Water this little herb to get the most out of its flavor, and harvest the softer tops of the stalks so that your thyme will continue to produce the tasty herb during the late spring and summer.


Now here’s a plant that will really spice up your window box (see what we did there). Peppers will need direct sunlight throughout the day to grow well and will need to be watered semi-frequently to prevent the soil from getting too dry. Keep in mind that these are one of the bigger plants you can place in a window box, so you will need to plant them as deep as you can (up to 12 inches deep) and might need a stake to keep them upright.

Hopefully this article about the many different fillers and herbs/vegetables you can plant in your window box has been helpful. Some more research will likely be required if you have little to no experience with some of these plants, but this will certainly be enough to get you started, happy gardening!

About H Potter:

For nearly 30 years, H Potter has been proudly serving the home and garden industry as an innovator and a trusted family-owned business. With a wide variety of home and garden products, our mission has been to provide a high quality product to the at-home gardener that is both artistic and functional. Thanks for visiting our blog, we hope you’ll take some time to check out the other wonderful blog posts and pages throughout our website. 

Back to blog