The best thing about containers is you can put them anywhere (on steps, on a deck or balcony, around a pool), you can move them around if you get bored, and you can fill them with different displays for each season.

Choose The Right Container:
Planters come in all styles, textures, sizes, and colours. Choose containers that will harmonize with your planting and colour scheme. Also, think about getting some large enough to have some serious visual impact. Whether you decide on wood, clay (terra cotta), plastic, concrete, glazed ceramic, cast iron, or a moss-lined basket, all containers, even window boxes, need a drainage hole at the bottom. If excess water cannot drain, your plants will suffer from root rot. Saucers are also a good idea to prevent staining on the surface below.

How To Plant:
Cover the drainage hole with pieces from a broken clay pot or small stones and add 1 cm - 2 cm (0.5" - 1") of gravel or more broken clay bits. Use Parkwood™ Premium Potting Mix, a potting soil that's specifically blended for container growing. Do not use topsoil or triple mix. They're too heavy, create poor drainage in a container, and the plants won't flourish. Water your plants well before removing them from the containers you bought them in because dry roots are brittle and break very easily. If there are masses of roots and you can barely see any soil, pull them gently apart with your fingers. Firm plants into the soil and water with Parkwood™ Transplanter 5-15-5 to the point where the water just begins to seep out of the drainage hole.

What To Plant For Spring:
Since trees haven't leafed out in April, you don't need to worry quite so much about the shade factor. Also, this planting is only meant to be around for 4 to 6 weeks. The flowers that cheer us most after a long winter are Spring-flowering Bulbs, Pansies, and Primulas. You can easily purchase potted bulbs in early April and transfer them to your container(s). For height, select Daffodils or Tulips, surround them with Hyacinths (which have the added feature of fragrance) or Dwarf Daffodils, and then edge the pot with Crocus, Dwarf Reticulated Iris, Pansies, Violas, or Primulas. Variegated English Ivy is an interesting foliage plant that can be added to spring planters.

What To Plant For Summer:
All of the plants mentioned above can be transferred around May 24 directly into the garden (or composted if you don't need them anymore). Leave the Variegated English Ivy as it's probably starting to cascade very nicely.

Now, you need to select plant material specifically for sun, partial shade, or full shade depending where each container is going.  Use taller plants to create a focal point at the back if the pot is placed against a vertical surface such as a wall or lattice. If the planter is in the open, put the taller plants in the center. Candidates for focal point plants and sunny conditions (6 hours of direct sunlight or more), are Geraniums, Purple Fountain Grass, Gerbera Daisy, Nicotiana, Sunshine Impatiens, Lantana, Marguerite Daisy, and Blue Victoria Salvia. There are a variety of edging and trailing plants that can be used around the perimeter of a sunny planter, including Petunia, Trailing Verbena, Million Bells, Ivy Geranium, Lotus Vine, Alyssum, Sanvitalia, Bacopa, Bidens, Licorice Vine, Blackie and Lime Sweet Potato Vine, Swan River and Dahlberg Daisy, Diascia, and Ivy.
For partial shade, pot up Impatiens, Fibrous Begonias, Fuchsia, or Calla Lily with Lobelia, Fan Flower, Ivy, or Lysimachia to billow over the edge. While there aren't as many choices for full shade, concentrate on pale colours, especially white, that will jump out from a dark background. Non-stop and Angelwing Begonias, Coleus, Browallia, Caladium, and Torenia all tolerate these lower light levels.
Vines can be grown in pots as long as support is provided. Use a trellis, tripod, or decorative obelisk placed right in the container. Annuals such as Morning Glory, Moon Vine, Sweet Pea, Cup and Saucer Vine, Nasturtium, and Scarlet Runner Bean produce a tremendous show. Another way to achieve this vertical effect is to use a flowering standard, for example a Tree Rose, Tropical Hibiscus, Fuchsia, Lantana, or Daisy that can be underplanted with either flowering (eg. Bacopa) or foliage (eg. Ivy) annuals.

What To Plant For Fall:
Flowering Cabbage and Kale, Asters, and Chrysanthemums are all frost-tolerant annuals for fall.

What To Arrange For Winter:
In frostproof containers arrange Pine, Juniper, Cedar, Spruce, Hemlock, or Spruce boughs with red and Yellowtwig Dogwood, Winterberry, and Curly Willow branches before the soil freezes. Add some large pinecones at the edge of the pot to fill in. As December gets colder everything will freeze firmly into place and some white mini-lights would add just the right touch for Christmas.

Container Maintenance:
Fertilize your annual containers with Flower Food 15-30-15 every 10 days to 2 weeks for maximum bloom. As soon as flowers fade, cut off the dying flower heads with a sharp pair of hand pruners. This process is called deadheading and prevents the plants from setting seed. Annuals that successfully produce seed don't feel the necessity to bloom anymore and take a lot of coaxing to bring back into flower.
Because containers are off the ground they dry out much faster than plants in the ground. Hanging baskets, in particular, dry out the quickest. In hot weather water every day or when you see plants just starting to wilt. If you're going away on vacation, someone will need to care for them.  Though containers require a bit more attention, they offer a lot of benefits. Not only do you get to enjoy the beauty of the pots themselves and what's in them but you can also arrange them and plant them differently every year. And that's not something you can do in the rest of the garden!