Janice Peterson: Thrillers, fillers, spillers make for killer potted plants
One of the easiest ways to spruce up your porch or deck is to grow plants in containers. Container gardening is also great way to garden in small spaces; even apartment dwellers can often find a bit of balcony to display a hanging basket or a pot. Another plus to container gardening is that the soil can be replaced every year to help avoid disease build-up, and weeding is minimal.
I love any kind of mnemonic or word game that helps me remember things—and the stupider the better! A rule of thumb for planting containers is “thrillers, fillers and spillers” a simple recipe that always works. The idea is that a planter should have a tallish planting with some “wow” factor placed in the center (the thriller), trailing plants that grow over the edge of the pot (the spiller) and a mid-sized plant that fills in the space between the thriller and the spiller (the filler). Voilą! Three plants and you're done!
Here's an example: purple fountain grass (Pennisetum) as the thriller, sweet potato vine (lpomoea) as the spiller, and million bells (Calebrachoa) as the filler. More than one plant of each variety may be required depending on the size of the container. The plants don't have to be floriferous; try something with colorful leaves like coleus. Containers are also a great way to incorporate vegetables and herbs—basil makes a great filler.
Of course every rule is meant to be broken. The thriller doesn't have to be dead center, especially if the container is against a wall. More than one plant variety can be used together as fillers or spillers. A thriller and spiller can be used without the filler for a more formal look. Also, some plants look great solo. I often will buy a beautiful winged begonia and place it by itself in a pretty pot.
Growing plants in containers is an easy way to experiment with plant and color combinations, and every year is a new trial! One other important rule is to combine plants that have similar growing requirements. A plant that does best in dry, sunny heat will be miserable living in the same pot with a shade and moisture loving plant. Finally, water your container—don't ever forget, don't ever let it dry out. Believe me; if you do let it dry out it will never forgive you.