Many gardeners who grow annuals do so because they have short growing seasons. When faced with a short growing season, it stands to reason that the gardener would want to find annuals that grow especially fast. So here are some faster growing annuals to consider when looking for things that will give you growth and color reasonably fast.
Pansies and violas, though best suited to cooler weather grow quite fast. Since they don't grow very tall, they tend to spread. They make an ideal choice for a cool weather border.
Petunias are fast growers, and they are better suited to hotter weather. Petunias grow taller than pansies but they don't grow very tall. They come in a wide range of colors. They are also well suited to growing in containers.
Marigolds are fast growing flowers. Although there are several types of marigolds, they typically grow quite fast and germinate from seed quickly. The smaller varieties are well suited to containers and will also work well just behind a border.
Snapdragons are fast growers. They come in a variety of colors, don't grow very tall, but really add a splash of color wherever they are planted. They would be a good flower for a container.
Morning glories are extremely fast growers once the seeds germinate. They are extremely easy to grow from seed. Once they start growing, they will grow very fast. Because they grow as a vine, they need some sort of support. They may also do well in pots.
The down side of growing morning glories is that they dump seeds everywhere and will spread all over after dumping the seeds. Plant them as far away from other flowers as possible or they may strangle the flowers.
Caladium, a plant that is in the aroid family grows from a tuber or tuberous root. They grow to about 2 feet in height but are best suited for shadier conditions. They thrive in humid conditions. They have leaves that are shaped like angel wings. Since they only grow to about two feet in height, they are well suited to growth in containers, and if grown in containers, they can be grown as houseplants, extending the growing season indefinitely.
Cosmos is one of my favorite annuals. In warmer climates, it grows as a perennial or reseeding annual. Plant in spring after the danger of frost. It grows extremely easily from seed and once started grows very fast. To encourage more blooms, dead head the spent flowers. If you wish to harvest seeds, leave the dead flowers on the stems.
Gazania is one of my all time favorite flowers. It is a short grower that grows easily from seed. Once established, it will grow very quickly. In warmer climates, it can be kept alive for longer. It will benefit from a high phosphorus bloom boosting fertilizer.
Coleus is a very fast grower and one that is easily propagated by cutting. Coleus is a shade lover and can also be grown as a houseplant. It does produce flowers, and if allowed to flower, one can harvest seeds. If you want to encourage the plant to grow bushier and fuller, pinch tiny new leaf growth and be sure to pinch to prevent it from flowering.
Geraniums are very fast growing annuals. They thrive in full sun and will bloom more continually if dead headed. They are easy to grow once established. they will tolerate some neglect, but prefer to be watered regularly.
Nasturtiums are very easy to grow from seed. Once the seeds have germinated, they will begin to grow very quickly. It is important to remove the dead flowers of nasturtiums to encourage new growth. The flowers of the nasturtium are edible.
Four o'clock, a member of the mirabilis family is a very fast growing bush. It is also known as Marvel of Peru. This flower only blooms in the evening, generally starting after 4:00, as its name denotes. It grows well in poor or good soil and will grow in any zone. In warmer climates, it grows as a perennial. It is a prolific producer of seeds, if the dead flowers are allowed to remain on the plant. The seeds are extremely poisonous if ingested. Four o'clock is attractive to hummingbirds, no doubt, because of the shape of the flower.
For shady areas, impatiens is ideal. They grow extremely fast, and the single variety tends to grow in masses, making it look a lot like a ground cover if planted in equally spaced intervals. The double variety grows slightly taller and looks like a tiny rose. Impatiens will grow well in the ground or in containers, but they need to be watered regularly or they will look wilted.
New Guinea impatiens is a sun lover that grows considerably taller than regular impatiens. Well suited to hot weather and containers, the purple color leaves offer a striking contrast against the bright colored flowers.
Zinnias are fabulous annuals that grow quickly and easily from seed. They come in a range of sizes and colors, some of which are quite small, while others are considerably taller. Zinnias are also useful as a long lasting cut flower. The spent flowers need to be dead headed to encourage more bloom production, but if allowed to remain on the stem, they will produce seeds that can be used in subsequent years.
This is not by any means an exhaustive list of fast growing annuals. Depending on the climate, the soil conditions and the quality of the plants or freshness of seeds, many flowers or plants will grow reasonably fast. Most annuals will grow faster if they are started from seed indoors far enough in advance of outdoor planting. In places where the climate is such that the growing season is shorter, getting a jump start by planting annual flower seeds indoors is probably a very good idea.