Photo by Joan Weed

Thriller! Spiller! Filler!   Have you heard this phrase?  Some have and it might be new to others.  It’s the design idea behind container planting.  Containers can be window boxes, clay pots, beautiful ceramics or a feeding trough.  They’re valuable in our summer gardens for filling in spaces, adding a pop of color or replacing some of those ephemerals we spoke of in the last column.

The idea is that you’ll need something showy as your thriller, the focal point of the arrangement.  Then you’ll want a few plants that will drape over the sides a bit to add a natural look. The filler is pretty easy to understand. This could be small flowered plants or even greenery to complete the arrangement by filling in between your other major plants.  Your material can consist of annuals but needn’t be confined to them. A perennial, small shrub or clump of grasses are smart ideas. If the material is perennial and hardy in our zone, you can add it to the garden when the season is done.

I sometimes use summer bulbs such as dahlias or eucomis (pineapple lily).   These would be thrillers for sure. One of my favorite thrilling plants is cardoon. The foliage is silvery and spiked. It grows pretty tall.  It’s actually an artichoke and last year mine produced two fruits!  Sometimes I add an herb plant especially to the pots closest to the back door. The spicy globe basil is like a miniature boxwood but it’s edible. Sage, rosemary or winter savory are all perennial herbs that are possibilities.  Fuchsia ‘Baumgartner’ is bright red and has sturdy stems making it a nice possibility for a focal point. Another that I’ve had success with is ornamental pepper ‘black pearl’.  The foliage is interesting as well as the fruit.

Spillers can be diascia, petunias, bacopa, or nemesia.  There are so many choices all grown for you at the local nursery.  The planting should be crowded to fill the spaces, but this will mean competition for food and water so containers need more attention than garden planted material. Daily watering if Mother Nature does not provide some rain. There are time-release plant foods to mix in with your potting soil. And a  word here about the soil. Do not try to use soil from the back yard.  It is usually too heavy. Choose a packaged, specially, formulated mixture of compost and soil from the garden center or hardware store. Some come with fertilizer added, but I prefer to add my own so I may choose the amount and kind I like.

The fillers can be something with small leaves or blooms to add a contrast in texture or color while doing its job of completing the design. Again, the nursery will offer you a big selection. Pick them out early while selection is good but don’t rush to put them outside till you are sure the temperatures are steady and warm. They can be kept in a protected area till used.  I find that some plants run out of vigor before the season is done. A few will benefit from cutting back if the growing season is long enough.  Otherwise, you might need to replace a plant or two. This is tricky, since by that time in the season, the selection has dwindled.  Bargains can be found if the replacement plants were well cared for at the nursery.

Another benefit of container planting is mobility. If you should need to fill a hole in the landscape or bed, move a filled pot to the area.  Now is the time to put your containers together. Have fun choosing and be creative.  Keep in mind thriller, spiller and filler!