There are principles designers use when creating plant combinations for containers, and their secret is:  these principles are simple enough that even a novice can make good use of them!  Perhaps you’ve heard of thrillers, fillers and spillers?  Every gardening magazine I read lately talks about this formula for success.

• Thrillers ~ These are the eye-catching, architectural element in a mixed collection that adds the drama and pizazz.  I’m talking about those spiky, upright plants – the dracaenas,  phormiums, sedges, blue fescue, Hakonechloa all-gold Japanese forest grass, Imperata ‘Japanese blood grass’, black mondo grass – this list goes on and on.  Lavender could provide that spiky look, in addition to great fragrance and color.  However, don’t limit yourself to grasses; anything dramatic and eye-catching will provide the Thrill.  A single melianthus would give a striking, impressive upper canopy to a container garden, as well as unusual gray-green color in jagged-edged leaves.   For those of you interested in incorporating edibles into your containers, think about a columnar apple tree or small olive, surrounded by lavender and herbs.  Other ideas to consider here:  cordyline, canna, upright junipers, bananas, corkscrew rush.
• Fillers ~ These provide the body of the container garden – the mounding, billowing plants around the central part of the collection.  In a 16″ pot, you would probably want to use three to five small 4″ plants.  Fillers can be anything that is relatively upright and mounding.  Plants that make good fillers:  begonias, plectranthus, cuphea, dusty miller, heliotrope, coleus, osteospermum, caladium, ornamental pepper, lantana, diamond frost euphorbia,  petunia, dahlia, Tagetes gem marigold, callibrachoa (also known as million bells), geranium, and zinnia.  Perennials such as heuchera, fern, and hosta can also make wonderful fillers, so be sure to explore outside the realm of annuals.
• Spillers ~ These delicate plants cascade over the edge of your pot, softening its edges and grounding your garden to the earth.   You could probably use two or three of these, to provide spillage around the perimeter.  Many of the perennial groundcovers work here – lamium, vinca, sedum Angelina, and creeping jenny.  And of course, there are lots of annuals that spill beautifully – nasturtiums, trailing petunias, ipomoea (potato vine), verbena, callibrachoa, and bacopa.  Other very effective spillers:  lotus vine, scaevola, helichrysum (licorice plant),  tradescantia, sweet alyssum, dichondra ‘silver falls’, trailing coleus, verbena,  portulaca, trailing lobelia, torenia, trailing fuchsia,  alternanthera, and creeping wire vine.

When making your plant selections, remember to group plants with similar dispositions.  If you plant a water-loving plant with one that is drought tolerant, you will have less success than if you select all drought tolerant plants for the same container.  Likewise, some plants prefer a shady corner rather than full blazing sun, so grouping like-minded varieties together will ensure your success.  That is one of the great things about container gardens, the ability to create these little microclimates of great plant collections, and placing them exactly where they will thrive. 

Once you know the conditions you are planting for (sun and moisture), you can begin the design process.  First to consider is color.  There are many ways to go here; some  love a monochromatic color scheme, with shades of one color.  Others prefer the energetic pizazz of using opposites on the color wheel:  blue and orange; red and green; yellow and purple.  Analagous color schemes use colors adjacent on the color wheel: reds and oranges; reds and purples; yellows and oranges.  Next to consider is texture.  Using a combination of fine-textured leaves, larger leaves, spiky, shiny, flat, fuzzy, serrated, smooth — the textural options are practically endless.  You wouldn’t want to use too many textures in one collection, but an assortment provides an interesting visual balance. 

A nice finishing touch for container gardens is to mulch the surface with something complementary to the design.  Rock, shredded bark,  moss – any of these hold in moisture and give an extra polish to your masterpiece.

Container gardens are easy to make and fun to create – let your imagination run wild!