First published on garden.org on May 7, 2009, by Suzanne DeJohn
For years I avoided planting petunias and geraniums. I suppose it had something to do with my job as a gardener in Boston. Deadheading thousands of purple petunias -- the "seasonal color" favored by our corporate clients -- left me with arms and hands stained purple. At least people kept their distance on the subway ride home from work. And the scent of those geraniums! (Maybe THAT's why people kept their distance.) But time has softened the memory, and now I see petunias and geraniums as the workhorses of the summer garden. A planter overflowing with these easy-care plants is a sure bet.
But maybe you want something a little "edgier" -- or at least more unusual. A few years back one had to hunt for unusual annuals, such as diascia, angelonia, and alternanthera; now, these beauties and more are readily available. So be bold this year!
One of my favorite no-longer-unusual plants is osteospermum -- an unwieldy name for such a pretty plant. The plants' daisylike flowers come in several colors, many with blue centers. The undersides of the petals are often darker then the tops -- on 'Soprano White' they are a striking iridescent bronze-purple -- making them perfect for tall containers where you're more likely to see the flowers up close. The flowers of 'Orange Symphony' aren't a jarring neon orange, but more of a milky Creamsicle orange, gentler on the eye and easier to mix and match with container companions. Combine these with an ornamental grass, such as Phormium 'Terracotta', with leaves striped in a bronzy salmon-orange, green, and white, and you've got a sure winner.
Here are a few things to keep in mind when choosing plants:
1. Select plants with differing growth habits. For example, combine spiky grasses with shrubby verbena and cascading sweet potato vine.
2. Make sure plants are compatible. Planting sun-lovers that require excellent drainage with shade- and moisture-loving plants is a recipe for disappointment.
3. Use foliage to your advantage. Choose dark-leaved plants to complement light or bright flowers, or chartreuse-leaved plants to brighten a planting.
4. Consider fragrance, especially if planters will be located near a doorway or window.
Thinking Outside the Pot
Consider mixing edibles with your flowers. How about including an ornamental pepper surrounded by trailing diascia? (The fruits of ornamental peppers are usually very hot, edible to some but not me!) Or try 'Bright Lights' Swiss chard, with multicolored stems and leaves, as the focal point of your container. Culinary herbs, such as purple sage and bronze fennel, are ornamental, plus a sprig or two can liven up dinner. Edible flowers, such as nasturtiums, combine well with herbs, such as purple basil, for an attractive and tasty combo.
Plan for the Seasons
Annual flowers can be categorized as either cool-lovers or heat-lovers. Cool-lovers can withstand light frosts but begin to flag when temperatures soar. Heat-lovers won't tolerate cold but thrive in the heat of summer. Take advantage of these characteristics by planting a succession of crops in your containers. You might start with dianthus in spring, replace these with verbenas in summer, and follow up with ornamental kale in autumn.
No matter what you are planting, your preparations begin with the container and soil. First, make sure your container has drainage holes. If the drainage holes are blocked when the planter is set on a surface, try placing the planter on casters or on a tray of pebbles. The water must be able to drain freely.
Use a high-quality potting soil. Avoid using garden soil, which often drains poorly and may contain disease organisms. You will be asking a lot from your container plants; you want them to flower and thrive all summer, despite having their roots confined to a limited space. So start them off right with a top-quality soil.
The main difference between container and garden plantings is that you'll need to water and fertilize container-grown plants more often, since roots are confined. Note that small containers may need watering daily -- even twice daily -- during hot, sunny weather. Most annuals benefit from regular deadheading to promote more blooms.
You'll also need to keep an eye out for insect and disease problems. While container-grown plants are sometimes less vulnerable to pest attack because they receive extra attention and/or are kept at a distance from the rest of the garden, you'll want to examine the foliage and flowers regularly. Many insects can be controlled by simply hosing them off the plants every few days. If this doesn't control the problem, try insecticidal soap.
The benefits of growing in containers are many: You can change out plants and arrange pots to suit your whim; you can place containers right where you want them; city dwellers can enjoy plants on their balconies. Containers are also perfect for experimenting!