Late Summer Merges Closer To Autumn

Late summer flowers are still blooming.

It always seems that by the time the garden gets as productive as it can, it is already time to get ready for the next season. Pretty soon, cool season annuals will be arriving in nurseries to replace warm season annuals that had been so colorful all summer. If seeds are to be collected from summer flowers for next year, this would be a good time to do it.

Seed for certain cool season vegetables like broccoli, cauliflower, cabbage and kale, can be sown in flats or cell packs now to have seedlings ready to put out into the garden as warm season vegetables finish in autumn. If there is space available in the garden, turnips, turnip greens and beets can be sown directly. Carrots should probably wait a few weeks or so to get sown directly.

Although corn of a single variety sown in a single phase tends to ripen at the same time, different varieties planted in different phases can extend the season significantly. Those that continue to produce until autumn are greedy for nutrients and water. Squash and tomatoes likewise appreciate a bit of fertilizer and regular watering, even as the weather starts to fluctuate this late in summer. However, fertilizer does not need to be applied in the last month of expected production.

Zucchini should be harvested when they get about six inches long, not only because they are best when immature, but also because the plants are more productive if regularly deprived of their fruit. If plants have the choice, they prefer to concentrate resources into fewer large fruit instead of more small fruit. The problem is that the larger fruit is tough and lacks flavor.

Hubbard, butternut, acorn and other winter squash get the opposite treatment. Each vine should produce only a few fruits. Those that produce smaller fruits can sustain more than those that produce larger fruits. Yet, excessive fruit exhausts resources, which compromises fruit quality. The fruit that will continue to grow and ripen through autumn should already be somewhat developed. The smallest of excessive fruit, or underdeveloped fruit should be removed.

Cockscomb

Plumose cockscomb blooms with pinata colors.

The flowers of the two different specie known as cockscomb do not seem to be as closely related as they are. Celosia cristata exhibits two or three inch wide, weirdly stunted and crested blooms that resemble the combs of roosters, although the most popular varieties are so densely furrowed that they look more like fuzzy little brains. Celosia plumosa, as the name implies, has plumose flowers that look more like three or four inch long pampas grass flowers than like anything associated with chickens. What they have in common is their very bright red, orange, yellow, pink or white blooms. Foliage can be bright green to rich bronze.

As short lived annuals, cockscombs blooms only for about two months from the middle of summer to autumn. As cut flowers, they can last a week or two. However, because those popularly grown as summer annuals are mostly less than a foot tall, the flower stems are rather short.

Summer Annuals Are Grateful For Deadheading

Blooming through summer is serious work.

So many of the pretty warm season annuals planted last spring are now at their best. Sweet alyssum, lobelia, verbena, moss rose and busy Lizzy never stop blooming, and only get more colorful as they grow through the season until they get replaced by cool season annuals in autumn. (It is unfortunate that busy Lizzy, which had been a standard warm season annual for so many years has become less available due to disease.) However, French marigold, petunia, floss flower, cosmos, statice, pincushion flower (scabbiosa) and zinnia need a bit of attention to perform as well that long.

These few warm season annuals can get tired of blooming if not ‘deadheaded’ (groomed of deteriorating flowers). Deadheading not only keeps plants looking a bit neater, but also prevents the diversion of resources needed for continued bloom into the generation of seed. As far as these blooming plants are concerned, seeding for the next generation is their priority anyway. As long as they are not allowed to set seed, they will continue to try, by producing more flowers to replace those that fade and get removed without setting seed.

Cosmos, statice and pincushion flower can continue to perform adequately without deadheading. The main advantage of deadheading these annuals is the removal of fading flowers. (There probably will not be much left for cosmos.) Many people actually prefer to leave fading cosmos flowers to disperse their seed for the following year.

Petunia is perhaps one of the more demanding of warm season annuals. It often needs to be clipped back in the middle of the season, right when it is expected to bloom the most. The best way to avoid serious pruning at one time it to keep plants snipped back lightly but continually as they grow, so that they can not develop the awkwardly long and weirdly jointed stems that eventually stop blooming. Short stems that stay close to the roots are the healthiest and most productive.

The various types of cockscomb are odd warm season annuals that become available halfway through summer, just in time to add color if some of the annuals planted earlier in spring are not performing adequately, or are finishing early. Of course, all of the other warm season annuals will still be available in nurseries until it is time for cool season annuals next autumn.

Petunia

Petunias are quintessential warm season annuals.

There are too many varieties of petunia to be familiar with nowadays. The species name is Petunia X hybrida because almost all are hybrids of two primary species, as well as a few others to complicate the situation. The color range of the bloom of these hybrids now lacks only a few colors. (GMO orange petunias are only beginning to become available.) 

Besides an impressively extensive color range, bloom can be spotted, speckled, striped, blotched, haloed or variegated by too many means to list. Flowers can be rather small or as wide as four inches. Some are surprisingly fragrant. Some have frilled double flowers. Stems of cascading types may sprawl wider than three feet while only a few inches high. 

Petunias are warm season annuals that perform from spring until frost. They can survive as perennials for a few years if cut low for winter. Cool season annuals can obscure and shelter them until they resume grown in spring. They prefer rich soil, systematic watering and sunny exposure. Although mostly sterile, some appreciate occasional deadheading. Trimming during summer may promote fluffier growth for lanky stems.

Trailing Lobelia

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Lobelia may bloom beyond next summer.

No other bedding plants exhibit such rich blue as trailing lobelia, Lobelia erinus. Cultivars with white, purplish pink, purple or sky blue bloom are still not quite as popular as the favorite cobalt blue bloom. Individual flowers are tiny but very profuse and uniform. Some have white centers. The narrow leaves are tiny as well, and finely textured. Some cultivars have dark purplish bronzed foliage.

Individual plants are only about three to six inches high and wide. Cultivars that are more rounded and densely foliated are excellent for edging. They are very popularly planted in single rows, and alternating with alyssum. Trailing types exhibit wispier growth that stays a bit lower and spreads a bit wider. They do not trail far, but cascades nicely from urns and hanging pots of mixed annuals.

Although grown as a warm season annual, trailing lobelia can survive as a short term perennial where winters are mild. Fresh new growth develops out of the centers of overwintered plants about now. If pressed gently into the soil just before they are replaced by new growth, scraggly outer stems can develop roots. They just might grow into new plants before the originals eventually die off.

Bedding Plants That Defy Seasons

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Some seasonal annuals are really perennials.

Bedding plants that go into the garden in spring are generally warm season or summer annuals. They should perform through summer until the weather gets too cool for them the following autumn. Bedding plants that go into the garden in autumn are generally cool season or winter annuals. They should perform through winter until the weather gets too warm for them late the following spring.

That sounds simple enough. Each type of bedding plant performs best within a specified season. Since they are annuals, they complete their life cycles within a single season within a single year. Of course, it is not so simple here where seasons are as unique as they are. Winter is mild. Summer is arid. Some bedding plants that are annuals in harsher climates may survive as perennials.

For example, busy Lizzie and wax begonia are warm season annuals in most climates. They succumb to frost as weather cools in autumn. Locally, they can survive through winter if sheltered from mild frost. Any that survived through last winter can regenerate now. As bedding plants, they will not be as uniform as they were last year. However, their variability would be fine for mixed bedding.

If sheltered and warm enough, wax begonias may actually continue to perform right through winter. If they dislike the aridity of summer, they can even perform slightly better through winter than they do through summer. Their best performance is often about now and again in autumn, between the two extremes of summer and winter. They challenge their designation as a warm season annual.

Even some of the bedding plants that really are annuals may not behave as such. Alyssum and nasturtium can disperse seed to replace themselves before they finish. They are not true to type, so their progeny eventually revert. Nonetheless, simple yellow and orange nasturtium and white alyssum are splendid for many relaxed gardens. Nasturtium might perform better in summer or winter.

Bedding plants usually know more about what they should be doing than those who are managing and manipulating them.

Angelonia

41008Angelonia is one of those warm season annuals that can actually survive through winter as a pernnial to bloom again next spring. It may even want to continue to bloom untill frost. The flowers can be blue, purple, red, pink or white, and look something like small snapdragon flowers. Most have spots or stripes of an alternate color or two in their throats. Some modern varieties have fragrant flowers. Plants can get a foot or two tall, and almost as wide. In sheltered spots, angelonia can be cut back as soon as it starts to look tired in autumn. Exposed plants might be happier if cut back significantly later, as winter ends. Old growth may be unsightly for a while, but can protect interior stems and roots from frost. Besides, pruning stimulates new growth that will be more susceptible to subsequent frost.

French Marigold

P90921KActually, French marigold, Tagetes patula, is no more French than African marigold is African. All are from Mexico and Guatemala. They were merely popularized and bred respectively in France and Africa. There are now hundreds of varieties. Yet, their color range is surprisingly limited to hues and shades of yellow, orange and ruddy brown. White marigolds are really just very pale yellow.

While African marigold is only occasionally grown for bigger cutting flowers on taller stems, French marigold is much more popularly grown for late warm season annual color. Because it blooms late in summer and early in autumn, and continues only until frost or sustained rain, it is often planted if earlier warm season annuals deteriorate while it is still too warm for cool season annuals.

French marigold can get more than a foot tall, and almost a foot wide, but typically stays closer to the ground. The delightfully aromatic and intricately textured foliage is rich dark green. Removal of deteriorating flowers (deadheading) promotes continued bloom, although a few spent flowers might be left to produce seed. Mildew can be a problem if watering is excessive or late in the day.

Madagascar Periwinkle

40924Like gardenia, dogwood and snapdragon, the potentially finicky Madagascar periwinkle, Catharanthus roseus, is often challenging to grow. It enjoys, but seems to prefer more humidity than it gets here. The happiest plants can get nearly two feet tall and wide in sheltered and humid spots. (They can get even larger in exposed spots in humid climates.) Yet, most of us are satisfied with relatively scrawny plants less than half a foot tall.

Madagascar periwinkle is popularly grown as a warm season annual until the weather gets too cool in late autumn, but it can tolerate a bit of cool weather, and can even survive as a perennial through winter if sheltered. The one or two inch wide flowers have five petals and small red centers, and can be white or various shades of pink, pinkish red, lavender or pastel orange. All parts of Madagascar periwinkle are incidentally toxic.

Morning Glory

90807A landscape designer would have more fun describing both the modern and the good old fashioned varieties of morning glory. Their vivid colors are so resplendent. Their rich green foliage is so luxuriant. Their delicate vines are so elegant. Hey, perhaps this is not so difficult. Anyway, the popular garden varieties of morning glory are descendents of various species of the genus Ipomea.

Except for a few obscure types, and the perennial blue dawn flower, popular garden varieties of morning glory are surprisingly complaisant annual vines, which grow from seed sown at the end of winter. Without getting too invasive or weedy, they sometimes reseed where they get watered, although they might revert to a more feral state after a few generations, or after the first generation.

Some varieties of morning glory have the potential to reach single story eaves, although most stay a bit lower, and some varieties do not get much higher than a doorknob. They work well on small trellises, or even simple stakes, and are just right for picket fences. The simple two or three inch wide flowers are rich hues of blue, purple, red, pink and white, some with spots, stripes or streaks.