Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
May, 2008
Regional Report

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This cheery combination of cosmos, zinnias, daisies, and petunias sings for me all summer long.

In Celebration of Annuals

Since they only stay in the garden for one season, annuals offer an opportunity to experiment with different foliage textures and flower colors each and every year. If you don't like the effect you've created one year, you can simply chalk it up to experience and try again next year, without having to move plants around as you would with perennials.

I think annuals are most effective when planted in combinations of brightly colored foliage and flowering plants in a bed that is accessible from all sides for visibility and ease of maintenance. You can make a bed more formal by planting a solid block of plants of the same variety and color. Separated by neat strips of lawn, such single-color plantings are quite striking.

An even more impressive sight is a massed, single-color planting divided down the center by a band comprised of a flower that has a different but complementary color or growth habit. For instance, a dark, vivid color like the bluish purple flowers of 'Periwinkle Blue' lobelia might combine well with the white flower mounds of 'Floral Lace' dianthus. Both plants are similar in growth habit -- low, mounding, and normally used for edging beds, and in our cool summer climate lobelia will tolerate full sunshine.

Annuals work equally well in less formal designs, and they fill an important role by giving you a brilliant palette of color. They can be inserted into open spots around perennials and flowering shrubs. Adding annuals to a perennial border can bolster the effect of the whole, ensuring a continuity of color and interest even when the perennials are not in bloom. They are great for creating rhythmic splashes of color, for linking different parts of the garden together, and for helping to carry a particular color theme through the garden during the entire growing season.

Some of the best annuals for mixed border plantings include tall species such as 'Hummingbird' nicotiana, 'AngelMist' angelonia, nemesia, 'Butterfly' pentas, or the vibrant 'Red Hot Sally' salvia. For mid- and late-season color at the front of the border, use annuals such as 'Fiesta' double impatiens or 'Dreamtime' strawflowers.

With all their different heights, colors, and forms, it's entirely possible to plant a spectacular border of just annuals. Since most annuals flower at the same time, and over an extended season, you may want to choose varieties that will complement each other. You can strive to create a particular color scheme (pink, blue, and white; yellow, blue, and orange), or simply go for a full-blown riot of color.

Planting Annuals
In general, annuals prefer well-drained soil with a pH between 6.3 and 6.7. Digging in a good quantity of peat moss or compost will help to build up the soil's organic matter and allow the plants' roots to spread quickly and get off to a good start.

Set out young plants at the recommended spacing to prevent them from crowding each other once they have grown and matured. When you remove the plants from their cells or containers, gently break apart the root mass. This encourages roots to spread quickly into the surrounding soil. Fertilize at planting time with an organic or slow-release fertilizer.

Ongoing Care
Once they start blooming, most annuals can be coaxed into flowering all season long until cold temperatures or frost put an end to their display. However, to keep them flowering and looking good, you will need to perform some routine maintenance.

Deadheading is the most important task, and it involves pinching off old flowers as they begin to fade. The reason for doing this is simple. Annuals live to flower quickly, produce seed, and die. As long as you keep deadheading blossoms, the plants will continue to produce flowers; once you stop, the plants will slow or stop flowering and put their energy into maturing seeds. Pinching off spent blooms is quick and easy, and it ensures season-long bloom.

If you fertilized at planting time, you shouldn't have to fertilize annuals again during the season. With annuals, the flowers are the main focus, and overfertilizing can lead to lush foliage growth at the expense of bloom. An exception to this rule is container-grown plants, which usually need to be fertilized every few weeks to maintain a colorful show.

Annuals have shallow root systems and therefore require a regular supply of water. Avoid overhead watering if possible, which can stain some types of flowers (such as petunias), and make them look unattractive. It also can contribute to fungal diseases. For best results, use a soaker hose or other drip irrigation system, or direct your watering can right at soil level.

Annuals are such reliable and rewarding plants. They bring the brightest colors of the plant world to your doorstep, and their quick growth can instantly transform a drab spot into a summer party place. Best of all, when you run out of room in your garden, annuals adapt wonderfully well to containers and hanging baskets.

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