Container Gardening Basics: Thrillers, Fillers and Spillers
This post discusses the basics of Container Gardening, including a discussion of Thrillers, Fillers, and Spillers. We also detail specific plants that fill each role in a container garden.
With spring fully here and summer not too far off, my mind is churning with everything garden-related. I’m planting my vegetable garden and pondering what plants to add to my flower garden so that I can have cut flowers from spring through fall. I am noodling all my containers and considering what combinations of plants to mix this year.
While I love my vegetable and flower gardens, I always enjoy putting together my containers. I think it’s that I get to start with a brand new palette each year and find a combination of plants that really speaks to me that makes container gardening so appealing to me.
Table of Contents
I attended a Container Gardening workshop through my local Arboretum several years back and was introduced to the terms Thrillers, Fillers, and Spillers as they relate to container gardening.
I’m not sure who coined those terms, but Martha Stewart, Home Depot, and other sources have used them when discussing Container Gardening Basics 101.
Container Gardening Basics: Thrillers, Fillers, and Spillers
Thriller Plants
Your container’s ‘Thriller Plant’ will be that plant that is, as its name implies…the real standout of your container garden.
This plant will typically be the taller one, placed in the middle or back of your container. It will feature dramatic foliage color, structure, or flowers. I usually have one great Thriller plant in each pot.
Ornamental grasses, elephant ears, cannas, and taros all make great thriller plants.
Thriller Plant Suggestions
- Agapanthus
- Agave
- Alocasia, Colocasia (Elephant Ear)
- Aspidistra (Cast Iron Plant)
- Aster
- Astilbe
- Aucuba
- Baptisia
- Bletilla
- Brugmansia (Angel’s Trumpet)
- Canna
- Echinacea (Cone Flower)
- Hibiscus
- Hosta
- Kniphofia (Red Hot Poker)
- Lobelia
- Muhly Grass, Fountain Grass
- Panicum (Panic Grass)
- Rohdea (Nippon Lily, Japanese Sacred Lily)
- Salvia
- Yucca
In this pot, the thriller is the Golden Mop Cypress, with Strawberry Mop Coleus as the filler and the Ice Plant doing the duty of the spiller.
Filler Plants
The ‘Filler Plant’ is the plant that will provide a textural or color contrast/complement to your ‘Thriller’ and help fill in your container garden.
When I’m putting together my container garden, I like to place the plants in my shopping cart to see how they look together. I enjoy how the purple grass complements the pink Superbells (calibrachoa) and trailing antique rose, while the fluffy Diamond Frost (Euphorbia) contrasts with the spikes of the grass in the planter below.
In this case, the ‘Spillers’, Superbells and Antique Rose, also act as fillers.
Filler Plants Suggestions
- Maidenhair Fern
- Angelonia
- Artemesia
- Athyrium Fern
- Begonia
- Carex Grasses
- Coleus
- Cyclamen
- Dianthus
- Epimedium (Barrenwort, Bishop’s Hat, Fairy Wings, etc)
- Cranesbill Geranium
- Euphorbia (Diamond Frost)
- Heliotrope
- Heuchera (Coral Bells)
- Hosta
- Lantana
- Liriope
- Lycoris
- Nepeta (Catmint)
- Oxalis (Wood Sorrel)
- Pentas
- Persian Shield
- Polygonatum (Solomon’s Seal)
- Phlox
- Pulmonaria
- Ruelia (Wild Petunia)
- Salvia
- Scaveola
- Sedum
- Stokesia
- Zephyranthes (Rain Lillies)
In this almost monochromatic pot, two different coleus (Colorblaze Keystone and Colorblaze Maroon) vie for the thriller plant position, while the Lantana does a great job as a filler plant and spiller plant.
Spiller Plants
The ‘Spiller Plant’ is the plant that tumbles out of the pot, softening the edges. Look for a plant that will tie the 2-3 other plants together, complimenting or contrasting as needed.
Spiller Plant Suggestions
- Verbena
- Wild Thyme
- Emerald Carpet
- Sweet Potato Plant
- Euphorbia
- Scaveola
- Lobelia
- Golden Creeping Jenny
- Nasturtium
- Licorice Plant
- Lamium
There’s a lot of drama in this container, with the Purple Sweet Potato Vine playing counterpoint to the Purple Fountain Grass and the Red Sunstatia adding a bolt of color against the otherwise dark color of the container.
In a month or two, the Mandevilla vine in this pot will act as both the thriller and spiller plants. I’ll have to remember to go back and take a photo to see how it all comes together.
Window boxes benefit from the same ‘recipe’ of Thrillers, Fillers, and Spillers. The purple Scaveola and Apricot Lace Superbells seem to be the thriller plants, with the white Bacopa and Emerald Lace Sweet Potato vine sharing the duties of filler and spiller.
Once you have decided on your Container Pot combination or ‘recipe,’ play around in the dirt to determine the best placement; do you want your thriller to be right in the middle or off to one side?
And make sure to add a slow-release fertilizer to the dirt when you plant your container garden.
Frequently Asked Questions about Container Gardening
The size and material of your container can significantly affect the growth of your plants. Ensure the container is large enough to accommodate the plant’s root system and has adequate drainage holes to prevent waterlogging. Materials like clay or terracotta allow more air movement through the walls, which is beneficial for root health, but they dry out more quickly than plastic or glazed containers.
Always use a potting mix designed for container gardens rather than regular garden soil. The potting mix is lighter and provides better drainage and aeration, which are which is necessary for healthy root development in confined spaces. Some mixes also contain slow-release fertilizers and water-retaining polymers, which can be beneficial depending on your plant choices.
Watering frequency depends on several factors, including the material of the container, the type of plants, weather conditions, and the size of the container. A good rule of thumb is to water when the top inch of soil feels dry to the touch. Ensure that water flows freely through the drainage holes to avoid overwatering.
Regular maintenance is key. This includes watering appropriately, fertilizing regularly, and deadheading spent flowers to encourage new growth. Monitoring for pests and diseases is also important, as container plants can be susceptible to such issues. Adjust the plant’s location to ensure the right amount of sunlight, which can change with the seasons.
Absolutely! Many edible plants also have decorative features. For example, purple basil or chard can be an attractive filler, while trailing cherry tomatoes make an excellent spiller. Just be sure that all plants in the container have similar light and water requirements.
I love this planter with nasturtiums and strawberries I spied several years ago. 
In colder climates, many container plants will need protection since their roots are more exposed to cold temperatures than those in the ground. Options include moving containers to a protected area, wrapping them with insulating materials, or transferring perennials to the ground where they can be more cold-hardy.
More Container Gardening Ideas
Do you have a favorite container garden recipe, idea, or plant combination? If so, please share it. I collect container garden ideas just like I collect recipes for meals, and you can find some them here.
- Container Garden Recipes #1
- Container Garden Ideas #2
- Container Gardening Ideas #3
- Container Gardening Inspiration #4
- Vegetables for a Raised Bed Garden
- Fall Container Garden Ideas #1
- Fall Container Gardens #2
Bookmark this page or pin the following image to refer back to this discussion of Container Gardening Basics, including lists of Thrillers, Fillers, and Spillers.
Thanks so much for spending a few minutes of your busy day with me!
To ensure you don’t miss future content, pop your email in the pale green box on the right or click here. I usually send one email weekly, so I won’t inundate your inbox. I’m sensitive to an overflowing email inbox!
We will only use your email address to send you emails, no more than 1-2 weekly. In addition, you will have access to my growing library of knit & crochet patterns and other printables. Check back often as this library will continue to grow. You can unsubscribe anytime by emailing me or clicking on the “unsubscribe” link at the bottom of all emails.
And you can access many of the products I refer to on my Nourish and Nestle Amazon Page. You can access it here.
So, if you’d like to participate in the ‘subscriber benefit’ action, simply subscribe to Nourish and Nestle here or use the form on the right sidebar. It’s slightly towards the top.
I have sent all my subscribers the link to the Subscriber Benefits Library. If you missed it or misplaced it, let me know.
Until next time…
Lynn – thanks for the great tips – I still have a few planters left to fill and I am going to try your tips. I always wondered if there was a recipe that would helped in creating one . I found you at #WayWOW link-up.
Hi Debbie…I do love collecting container garden ‘recipes’. When you see one that works, why not borrow that idea for your home? I am so glad that I might be able to suggest some ideas and hope your garden looks beautiful this year.
Hugs, Lynn
Some of my containers look like they are exploding with plants right now, but I’ve got a few that I need to work on for late summer foliage. Great suggestions for the “thriller/filler/spiller” plants! I hadn’t heard those terms, but yes, that’s a great design approach for containers 🙂
Hi Liz, it’s always so trick to plant a container that looks good from early through late summer. Good luck with that. And the Thriller/Filler/Spiller ‘theory’ is so easy to remember and makes such sense when you are in the aisles browsing for your plants.
Thanks so much for swinging by today.
Hugs, Lynn
These are really beautiful! Sadly, my thumb is not so green. My neighbors have lovely flowers though!
? I’d imagine that with your wee ones running around you have very little time to do much of anything. They’ll be off in college before you know it and then you’ll have time to put together some fantastic container gardens. Thanks for stopping by.
Hugs, LYnn
I am terrible at arranging container gardens. I can cut and water it but I do not really know what to plant together. Your containers are beautiful and I am going to use this post to go by as I fill this empty container in my yard! Thanks!
I’m so glad that I might have helped you in planting your container gardens. I really do love putting the combinations together, like I said, it’s rather like getting a recipe right. I hope you have fun putting your container together.
Hope you are enjoying a wonderful weekend.
Hugs, Lynn
My hubby usually does all the containers, so I just filled him in and I got an eye roll…LOL! Actually, tomorrow I’m filling an old chair at our cottage and bought some plants for it the other day. I’ll share it on my blog next week, unless it turns out terrible…LOL. Have a great weekend and don’t work too hard. HUGS, Lynn! 🙂
You mean Mr. Cottage isn’t hip on the Thriller, Filler and Spiller method? Say it ain’t so! Tell him it’s not too late to jump on the bandwagon! Can’t wait to see what you do with that old chair at the cottage. Have fun with it.
Have a wonderful weekend.
Hugs, LYnn
Lynn, this is so cool! I never thought about container gardening theory before. But, it makes perfect sense! Once I get some outdoor space, then I’ll know what to do with my containers. 🙂
Thanks so much for the ideas, Lynn. I just moved and have to cheer up a boring terrace we have upstairs.
Thanks for sharing with us at Sweet Inspiration, hope you have a wonderful week!
Hi Pili, planting container gardens is a sure fire and easy way to sprucing up an outdoor space. I am so glad to have prompted some ideas for you, but knowing your creativity, there is no doubt you will put your own creative spin on your planters.
Have a great week.
Lynn
I have not done any planters yet this year. I am so far behind! I love the sweet potato vine as the spiller, you can get it so many colors and varieties. And then I usually go for marigolds, geraniums lemon balm and then a lemon grass. All of the above, except for the sweet potato vine are supposed to ward off mosquitoes, and we definitely need that so we can spend time outside!
All the planters you used as examples are so lovely. I will definitely keep my mind on the thriller, filler and spiller when I do choose my plants! Thanks for the great tips!
Lynn, these are excellent tips for a newbie gardener like me! Thanks to your post now I have my plants list in hand to get the right plants for the urns we have 🙂 Thank you so much for sharing!! xx
Hi Handan..it is handy to have a list to go by. But at the end of the day, they just need to all play well together. Have fun putting your urn gardens together. It’s a fun thing to do.
Thanks for swinging by today and sending wishes for a wonderful week.
Hugs, Lynn
I’m just going to sit here and admire a master at work. Respect for you Lynn and your amazing artistry! Beautiful living works of art!
Aw thanks Mary! But those aren’t all my planters..I WISH! I just take photos of planters I like and save the ‘recipes’.
Hope you have a beautiful week.
Hugs, Lynn
I’m new to gardening and looking to do 2 containers on my porch. Do I need to leave space between plants when I first plant my recipe?
Hi Melissa, that’s a great question but also one that is not real easy to answer.
If you are looking for immediate impact but not necessarily a long-term container garden, then you can really pack the plants in without a whole lot of space. The downside to this is that they will be more susceptible to disease and they just won’t thrive as they have no room to grow.
If you are looking to have a container grow throughout the season, then the rule of thumb I use is a plant for every 3-4 inches of pot diameter. So if you have a 12-inch pot you can put 3-4 plants in it. But take into consideration the spreading nature of plants versus the upright nature. Also, take into consideration whether you are talking a fast growing or slow growing plant and if you are planting from those little 6-pack cells or a larger 3″ pot.
If you are uncertain, you might gather some plants you like at your nursery and ask someone knowledgeable there about the growing habits and how many you could get in your container.
I hope that kinda help!
Hugs, Lynn