Since annual plants die back each year in order to enjoy their bright flowers again next year, gardeners will either need to plant them again in the spring or sow the seeds at the appropriate time. With so much happening in a single season, annual plants often grow very quickly and are useful for filling in bare spots between young shrubs or perennials.
Here are some of the top annuals for summer color.
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Nicotiana ‘Lime Green’ (tobacco plant) has masses of lime-green fragrant flowers, especially in the evening, from July to September. It is equally at home in the middle of a mixed border, or in a container. Grows to around 75 cm x 45 cm.
Cosmos is a star of a bedding plant. Not only does it make a great filler in a border and is easy to grow but it produces a succession of large flowers from early summer until mid-autumn.
Cheerful looking and easy to grow these bright summer annual flowers also attract butterflies. Cosmos flowers are a good choice for summer cutting garden or for a child’s first garden because of the way they grow so quickly from seed. Sow seed directly outdoors in the spring after danger of frost to enjoy a bounty of summer blooms.
Its feathery mid-green leaves are a nice foil, not just for its own flowers, but for other plants around it. Flower seeds are usually in mixed color packets. Try Cosmos bipinnatus ‘Purity’ which is white, and slightly taller and bigger flowered than the mixed colors, reaching a height and spread of 1.2m x 0.6 m.
A favorite hanging basket annual, nasturtium plants can have a trailing habit that is pleasing, and bright, edible flowers that last all summer long.
The colorful summer flowers also attract butterflies and hummingbirds so plant them near a kitchen window or other location where you can enjoy the animals that come to visit.
The large rounded leaves are very attractive but can attract aphids so check the undersides of the foliage.
Nasturtiums are some of the most colorful bedding plants, flowering from June to September. For something a little different Tropaeolum ‘Black Velvet’ has a deep red, almost black-looking, velvety flowers, contrasting magnificently against the green-grey leaves.
At 30 cm x 40 cm it will not take up too much space at the front of the border, and, if you need any further encouragement to find a home for it, this plant is also edible, the foliage having quite a peppery taste, and the flower petals making a pretty garnish.
Gerberas are other favorite annuals. Their array of colorful flowers from the near fluorescent pinks and oranges, to the pastel pinks and lemons, are sure to provide a color taste for every garden. Looking as good in pots as they do in borders these daisy-like flowers of up to 12 cm tall are sure to brighten up any garden.
For unique flowers with contrasting stripes, Gazania Tiger Stripes are easy to grow and will flower freely from June until October. Again, they are happy in containers or in a border, reaching a height and spread of only 20cm.
Bacopa is a trailing plant, commonly growing with white flowers, often used as plant filler in hanging baskets. Bacopa Sutera ‘Copa® Double Blue’ is the first double flowering bacopa, with blue flowers that gardeners find is an added value.
This Bacopa is early flowering continuing all summer with a thick strong growth habit. The plant is disease tolerant and appropriate for full to part sun gardens.
Dianthus chinensis ‘Diana Blueberry’ is the first blue-colored pinks. The two to three-inch diameter blooms are barely fragrant but still worth planting in a walkway garden. The bright green compact plant is upright growing to ten inches tall in part sun. This type of pinks tolerates heat, rain and windy sites.
Verbena Velox™ Series is an interspecific cross between Verbena and Phlox. This hybrid annual plant grows six inches tall with a trailing habit. Like the Bacopa, it should be added to a list of ideas for hanging gardens.
This plant roots easily, like another garden verbena, is heat tolerant with long-lived flowers like perennial phlox and very mildew resistant. For hot weather locations, this is an excellent summer annual.
Classic zinnias are drought and heat tolerant making them a long-lasting choice for summer blooms. Zinnias grow best in well-drained, moderate soil and are grown easily from seed sown outdoors after last frost date or started early indoors.
Zinnias love hot summers but are unfortunately susceptible to powdery mildew. For this reason, good air circulation in the garden is necessary. It is important when sighting this annual to space the plants apart as stated in the planting directions.
Zinnia Distance™ Series is a hybrid plant introduced two years ago that has improved tolerance for long hot summers. The full and semi-double flowers bloom in descriptively named colors like grape, orange, and cherry. The Zinnia ‘Distance™ Cherry’ has hot pink colored blooms. The plant grows well in containers or as an edger for planting beds. This Zinnia grows up to 16 inches tall.
Cleome is also known as “spider flower” because of the unique flower-cluster shape. Cleome’s summer flowers last for weeks and in moderate areas will bloom until the first frost. The summer flowers turn into long seed capsules that are attractive throughout the winter. Self-sowing can occur so once you sow seed the first fall, you should continue to enjoy these graceful and unusual summer flowers for years to come.
Most impatiens will produce flowers beginning in the summer if you start them from seed. Impatiens are available in a wide variety of colors and will provide a strong summer showing if you purchase healthy plants. Provide impatiens with lots of water but otherwise, the only other maintenance that may be needed is light summer pruning.
Not to be confused with the perennial Lobelia, known as cardinal flower, the annual lobelia is a common plant for summer containers. Lobelia’s full, rounded growth habit makes it a great filler for a hanging basket or flower pot and the bright blue or white flowers are attractive for many weeks. Sow annual lobelia early in spring or set out bedding plants in early summer.
Marigolds grow well in all but the coldest climates. They thrive in all kinds of soil and prefer full sun. Though some people find the odor offensive, the scent is said to repel rabbits from a garden.
Orange is the most common color, but some varieties produce yellow, red or brownish blooms. Petite marigolds, the smallest variety at only 6 inches tall, make an excellent border or first row in a flower bed. French marigolds grow to about 16 inches, and the crackerjack can get up to 3-4 feet tall.
Considered by some to be wildflowers, bachelor’s buttons (also called cornflowers) produce pleasing blooms in blue, purple, pink, or white. Height ranges from 1 to 3 feet, though most are about 18 inches tall. Bachelor’s buttons can be grown in any type of soil.
They prefer full sun or part shade. Deadheading prolongs the blooming season. However, it’s best to leave the autumn blooms intact, since bachelor’s buttons reseed themselves extremely well. In fact, these easily grown flowers act almost like perennials.
A hugely popular flowering annual, common in rock gardens and containers, is known as sweet alyssum because of its sweet fragrance.
A low-growing plant, sweet alyssum is highly fragrant and attracts honey bees, butterflies and hummingbirds to the sprawling clumps of flowers that almost completely cover the foliage early spring through fall.
Sweet alyssum can be started from seeds indoors during the winter, or sown directly in the garden after the ground has thawed in the spring. While sweet alyssum is a sun-loving annual that will die each winter, it readily self-sows in the garden.
It tolerates part shade so tuck the cascading 4-10” clumps into the garden anywhere. Sweet alyssum is most often seen as white-flowering cultivars but some like ‘Easter Basket’ or ‘Violet Queen’ have purple flowers but all will spill over the edge of raised beds in beautiful cascades of flowers.
This lovely cascading annual is grown for its foliage and while related to sweet potatoes grown as vegetables, the potatoes from this ornamental plant are small and bitter. The bright foliage of the sweet potato vine is anything but bitter, however.
Stunning green, chartreuse, dark black or variegated green and pink leaves (different cultivars are available) adorn the 2’ trailing stems. Sweet potato vine is especially well suited for containers, hanging baskets, border edges or allow the sprawling annual to twine underneath woody shrubs and larger perennials in a mixed border.
Trim as needed by cutting the tips of the sweet potato vine to encourage bushier growth. Sweet potato vines prefer full sun but tolerate part shade and stem cuttings can be taken in the summer for indoor winter propagation.
We are all accustomed to picking up vegetable seeds in the store each spring, and many times we also pick up marigolds and other annual flowers. Traditionally these are sown indoors to get a jump start on the season.
However, they can also be sown directly outdoors when the threat of frost has passed. Those seeds directly seeded outside tend to catch up with their larger indoor neighbors and by mid-summer, you will not know which is which. There are a couple of reasons for this:
Work the soil until loose and add humus or peat moss if needed. The easiest way to plant annual seeds is to dig a trench, sprinkle seeds generously in a row and cover lightly with peat moss.
Planting flowers in rows makes it easy to distinguish the flowers from the weeds and ensures you will get an even spacing of plants after thinning. But many people prefer the more organic method of “broadcasting “ seeds over the soil and covering lightly with topsoil or peat moss. You may have more success with this method if you purchase a package containing a variety of seeds combined with mulch and fertilizer.
Not all summer annuals though should be started from seed. One major determining factor is the length of time that it will take the seed to germinate and mature enough to produce a respectable flowering plant. This could exceed the number of days that you have in your average growing season, particularly those of you in the north of the continent.
In general, if your last frost date is before early May, then you can get fast-growing annuals into the ground by early June and into flower by the middle of July. This gives them a reasonable number of weeks for you to enjoy them.
Specific information that is on the back of the packet will help you decide if the seeds are likely to work for you. Many seed packets have a map of the USA divided into three or four sections. The earliest time to sow those seeds will be in the south and that date will likely be around March or April.
Next up will be the warm zones of lower 6 through zone 8 and these can sow annuals from mid-April onwards. The cooler zones of the Midwest and mountainous regions may be as late as June before they can sow tender annuals outside. This date is fine for some fast-growing vegetables but a little late for summer flowers.
The next piece of information you will need to find is where it tells you how many days to flowering or maturity. Typically this is in the range of 60 to 90 days, or two to three months.
Adjusting for local weather conditions that yield warm soil, you can plant your seeds approximately two weeks after the frost date, then add the maturation date and see when you can expect flowers. E.g.:
Last frost Date: April 15th
Plant seeds: May 1th,
Approximate bloom time: July 4th for 60-day maturation, Early August for 90-day seeds.
Clearly it is preferable to get the faster-growing seed!
“Sow thick, and thin” is the mantra for beginner gardeners. It’s best to sow the seeds thickly, to begin with, and plan on thinning them out in several stages throughout the growing process. When the seedlings begin to develop distinct leaves, thin them to about three inches apart.
After the plants are well established, thin them again, choosing the hardiest looking plants and pulling the weaker ones. Use the spacing information on the seed packet as a general guide, but don’t be afraid to leave them closer together than recommended.
Seeds need moisture to germinate. After planting flower seeds, water the bed with a light spray at least once a day. Once the seedlings are established, reduce watering to about three times per week.
Starting in midsummer, when the plants are well established, give them a good soaking only once a week, using a hose directly on the stems. Avoid watering during the heat of the day, to ensure that the water is well absorbed without too much evaporation.
Annuals need regular fertilizing to produce lush blooms. Fertilize about every two weeks using an all-purpose fertilizer, such as 5-10-5 or 15-30-15. Follow package directions. Be careful not to fertilize nasturtiums, however, because these flowers produce fewer blooms when fertilized.
Flowers bloom longer if you regularly deadhead the spent blooms. Snip off the blooms when they start to look brown. However, if you want to save the seeds, make sure you stop deadheading in the fall.
Some annuals self-sow if left to themselves in the fall. However, you may choose to harvest the seeds and replant them for more control. To harvest seeds, let the flowers go to seed. When dry, cut or break off pods and place them in a labeled paper bag for each variety. Hang the bags in a warm dry place to let the seeds dry thoroughly. When dry, separate the seeds from the pods and store in labeled envelopes or paper bags for use the following spring.
Although annual flowers have a short life, they make up for it by producing a riot of color all summer long. For a little bit of investment, you can enjoy a beautiful flower garden by growing annuals from seed.
So go ahead and pick up some annual packets, particularly if they are on sale, sprinkle some around the garden, keep well watered and enjoy a summer-long display or low cost, colorful plants.
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