Annuals that produce light, airy, delicate blossoms, such as bacopa and diascia, are most alluring when viewed up close. However, if you really want to make a statement with your annual garden, plant bodacious annual varieties that boast large flowers and bold colors.
When designing a mass planting for the biggest impact, it isn't just about choosing the right varieties. How and where you plant them is just as important. To create a vivid display for passersby, plant masses of flowers in a single color or in broad swaths of color. Mixing colors diminishes the bold effect. Plant showy annuals where they can be viewed from a distance so you can see the bed in its entirety.
Select bold-colored varieties with large flowers that bloom all season long. Purples, hot pinks, reds, oranges, and yellows draw the most attention to the garden. Pastel and white flowers are less flamboyant and are often best viewed up close.
You can change the look of a bed two or three times each growing season. For example, if you had a bed of red tulips in spring, after the flowers fade carefully plant the bed with bright red geraniums, taking care not to disturb the tulip bulbs. In late summer, replace the geraniums with garden mums. This is called succession planting, and it will give you a stunning visual impact from early spring to late fall.
Don't limit yourself to flowering annuals. Foliage annuals such as coleus and alternanthera have colorful leaves that will brighten spots that are too shady for the boldest annual flowers.
When planting masses of annuals, choose a location with good visibility from walkways, roads and your house. Till up the area and amend the soil with compost. Based on a soil test, add other nutrients and adjust the pH. Plant masses of single colored varieties in rows at the recommended spacing. Once they are established, mulch transplants with a 2- to 3-inch thick layer of bark mulch or pine straw. Keep the plantings well watered and fertilize every few weeks with an all-purpose plant food. Remove spent blossoms, and replace flagging plants as needed.