Time For Warm Season Annuals

Sweet alyssum is one of those warm season annuals that is too easy to grow to be taken too seriously.

Nasturtium and sweet alyssum seem to be more than warm season annuals. Like many other warm season annuals, they get established best if added to the garden just after winter, and then grow and bloom mostly during warm spring and summer weather. Then, if allowed to stay in the garden as cooler weather inhibits bloom somewhat , they survive through autumn and winter. By the time the original plants die out, new seedling emerge to replace them.

A potential ‘slight’ problem with allowing these annuals to naturalize (perpetuate naturally by sowing their own seed) is that fancier varieties eventually revert to a more genetically stable state. Sweet alyssum that can be various shades of pink or purple as well as white eventually blooms almost exclusively white after a few generations. Nasturtium that might start out with all sorts of shades of yellow, orange, red or brownish red eventually blooms with only basic bright yellow, bright orange and perhaps rarely, cherry red.

The reason that this is only a potential problem is that most of us are totally pleased with white sweet alyssum, and yellow and orange nasturtium! Another slightly more realistic potential problem with naturalization of sweet alyssum or nasturtium is that it leaves us no excuse to try different varieties. Anyone who doubts this should take a quick look through the online catalog of Renee’s Garden!

Nasturtium is easier to grow from seed than from small plants in cell pack, since small plants take time to recover from transplant. Besides only two or perhaps three of the multitude of varieties available as seed can be found in cell packs. Sweet alyssum can either be grown from cell pack or from seed, but like nasturtium, more varieties are available as seed. Although they grow throughout the year, both are still considered to be warm season annuals.

Busy Lizzy (impatiens), petunia, marigold, lobelia, cosmos and zinnia are some of the other popular warm season bedding annuals this time of year. Statice, cockscomb, verbena, moss rose and pincushion flower are also in season. Statice, tall varieties of cosmos and some varieties of zinnias make good cut flowers. Verbena, moss rose and pincushion flower are more often grown in mixed planting rather than as homogenous bedding. Although many more varieties are available as seed, cell packs of any of these warm season annuals provide more immediate results, especially this late in the season.

Candytuft

Candytuft is like a perennial alyssum.

Alyssum is popular because of its lightly fragrant and lacy white bloom that lasts through most of the year. It seems to be more perennial than it actually is because it sows seed to replace aging plants. Candytuft, Iberis sempervirens, is a bit less prolific with bloom and fragrance, but otherwise resembles alyssum. Without seeding, it can be nicely perennial. 

Candytuft does not get much larger than alyssum although it supposedly has potential to get almost a foot high and a foot and a half wide. Shearing after bloom phases enhances foliar density and subsequent bloom. Primary bloom occurs during late winter, spring, or perhaps early summer. Minor random bloom is possible at any time, particularly autumn.

Plants propagate readily by division of small tufts of rooted stems from within established plants. Alternatively, creeping outer stems develop roots if simply pressed into the soil or held down with stones. Pruning scraps are tiny and awkward to handle, but can grow as cuttings. When disturbed, candytuft exudes an aroma similar to that of related cabbages, which might be objectionable to some.

Alyssum

Alyssum can self sow quite freely.

Without becoming invasive, common alyssum, Lobularia maritima, can almost naturalize in favorable situations. It disperses seed profusely, so often appears where it is an asset to the garden. Since it is so docile, it subordinates to more vigorous plants that it mingles with. It does well on loosely set stone walls. If necessary, it is easy to remove or relocate. 

Common alyssum blooms with tiny but profuse white flowers. If they naturalize, varieties with pink or purple bloom eventually revert to white bloom after a few generations. Some varieties revert slower than others. Although popular as a warm season annual, alyssum can continue to bloom through next winter. Individual plants may survive for a few years.

Mature alyssum plants might get a bit higher than half a foot, but will get no higher than a foot. If they perform for more than a year, their progeny may begin to replace them before they get shabby. After removal, shabby plants, with a bit of shaking over bare spots, may share their last seed. Alyssum grows easily from seed, and is available in cell packs too.

Warm Season Annuals Are Hot

Petunia will enjoy warming spring weather.

Cool season annuals were cool just a few months ago. Now, it is getting to be about time to warm up to warm season annuals. They will become a hot commodity as winter yields to spring. Many begin to bloom with warming spring weather, and continue to bloom until autumn. Then, as the weather cools, they relinquish their space to cool season annuals.

Warm season annuals, or summer annuals (or warm season or summer bedding plants), are technically a bit early for a few regions. They should wait until after the last frost date, which might be later in the month for some climates. Even where frost is no threat, it may be too early to replace cool season annuals that continue to perform until spring weather. 

Warm season annuals only seem to be seasonable now because the weather has been so pleasantly mild and even warm. Some cool season annuals are already beginning to deteriorate, which facilitates their replacement. Warm season annuals might dislike cool nights and short days, but should appreciate the opportunity to disperse their roots early.

However, some degree of risk is associated with early planting of warm season annuals. Mild frost, although unlikely, is still possible in some climates, and could necessitate frost protection for vulnerable plants. Resumption of rainy and more typically wintry weather is more likely. Heavy rain can thrash fresh bloom. Sustained dampness can cause mildew.

Like warm season vegetable plants, warm season annuals can grow from seed or small plants from cell packs or little pots. Some prefer to grow directly from seed. Others prefer transplanting. Nasturtium, for example, prefer direct sowing. Petunia, which perform well after transplant as seedlings or small plants, are likely to languish if they grow from seed. 

Because seed take a bit of time to germinate, they can go into the garden slightly prior to the last frost date, and earlier than vulnerable seedlings. Similarly, they can start within a greenhouse early for later transplant. With proper scheduling, frost should no longer be a problem by the time seedlings emerge above the garden soil, or are ready for transplant. More variety is obtainable as seed.

Candytuft

As a companion plant, candytuft hides the less appealing lower growth of roses; or it can cascade from mixed planters.

Most roses that are grown for cut flowers are not very appealing in the landscape. They look better behind shorter perennials or shrubbery, with their taller flowering stems standing higher above. Mounding herbs like lavender, lavender cotton or rosemary, or small hedges of boxwood, dwarf hebe or Indian hawthorn obscurer their thorny undergrowth nicely. Candytuft, Iberis sempervirens, is a small perennial that gets just high enough to give a neat edge to a row of roses.

It gets gets about a foot deep, and can very slowly but eventually spread over a few square feet. The tiny, narrow and dark green leaves are less than an inch long. Inch wide trusses of minute white flowers resemble those of sweet alyssum, although lack fragrance. Sloppy plants can be restored by getting pruned almost to the ground.

Pansy

Violas are smaller versions of pansies.

This is one of the more familiar of winter annuals. Yet, pansy, Viola X wittrockiana, is not just one species. It is a diverse group of hybrids of a few species, and includes viola and Johnny-jump-up. Generally, viola and Johnny-jump-up have smaller and simpler flowers. Pansy generates relatively larger and more colorful flowers, with more intricate patterns.

The most recognizable feature of popular pansy is the distinctive floral patterns that look like floral faces. Individual flowers may display a few distinct colors within such patterns. Alternatively, flowers may be a single color. The color range includes white, blue, purple, yellow, orange, rusty red and black. Big flowers can be as wide as two and a half inches. 

Locally, pansy is a winter annual. The best bloom begins about now. If the coolest winter weather inhibits bloom, it is only temporary. Bloom is likely to resume before a lapse gets obvious. Although pansy is a summer annuals in other climates, it does not perform well in the locally arid climate during warm weather. Plants might get six inches tall and wide.

Cool Season Annuals Are Cool

Warm season annuals are now passé. Cool season annuls, such as these violas, are in.

Now that it is time for cool season annuals, it is difficult to remove warm season annuals if they are still blooming and healthy. that is probably why so many of us prefer mixed plantings, where cool season annuals can be added as needed to replace warm season annuals as they deteriorate. Some warm season annuals that are actually perennials, like wax begonia and busy Lizzie (impatiens), can be cut back and overplanted with cool season annuals, so that some might regenerate next spring as the cool season annuals finish. Petunias may be looking overgrown and tired, but are at least easier to remove without guilt.

Pansies and smaller but closely related violas are probably the two most popular of cool season annuals. They work something like petunias, but for autumn and winter. They are commonly grown in uniform beds, but work just as well in mixed plantings. There are not many colors that can not be found in pansies, although only a few of the more popular varieties can be found at any particular nursery. Some are ‘solid’ colors. The most familiar varieties have those funny ‘faces’ that pansies are known for.

The various primroses require a bit more effort because deteriorating flowers need to be removed. They can also be a problem for the few who are allergic to them (like poison oak). Like the warm season annuals that can survive as perennials through winter, some primroses, particularly English primrose, can survive through summer as perennials. English primrose displays bright cartoon shades of almost any color. Fairy primrose are more commonly pastel shades.

Stock has an intense and distinctively rich fragrance. Taller types are excellent cut flowers, but are not so practical for uniform beds. Even shorter types are probably best in mixed plantings, or in borders with lower flowers in front. The single or double flowers can be white, pink, purple and almost red.

Ornamental cabbage and kale are grown for bold rosettes of colorful pink, white or pink and white foliage. The shades of pink range from soft light pink to rich purplish pink and almost red bright pink. Cabbage provides more color. Kale has more variety of foliar texture. Ironically, both look rather weedy, and should be removed as they begin to bloom in spring.

Chrysanthemum are strikingly colorful cool season flowers, but rarely bloom as uniformly as they do when first planted. Because they bloom so profusely, they need to be groomed frequently. If they get what they want, they can perform for several years, blooming all sorts of shades of yellow, orange, red, pink, purple and white. Chrysanthemum also displays a broad range of flower structures and sizes, from minute to jumbo.

Sweet William, Iceland poppy, calendula and alyssum are also in season. Yellow or orange calendula, with single or double flowers, is best through autumn, but may mildew by winter. Alyssum is white or subdued shades of pink or purple, and is actually good throughout the year, and can self sow indefinitely.

Coleus

Coleus works both inside and out.

Without bloom, the richly vibrant foliar colors of coleus, Coleus scutellarioides, rival floral color of other warm season annuals. Striking foliar patterns are as exquisite as any floral display. Growth is efficient through the warmth of spring. Foliage might last until autumn. Late in its season, spikes of tiny blue flowers can be trimmed off to promote more foliage. 

With bright ambient sunlight, coleus is more perennial as a houseplant. However, it may get persistent with pesky bloom as it matures. Some who grow it prefer to let bloom, and then prune it back afterward. Recovery from such pruning can be slow. Vegetative stems, without bloom, root easily as cuttings even in water. New cuttings can replace old plants. 

Coleus foliage is intricately variegated with countless combinations of green, chartreuse, yellow, orange, red, burgundy, pink, white and brown. Variegation can be symmetrical or random. Leaf margins may be deeply lobed or just serrate. Modern cultivars might be no better than old fashioned sorts. Mature plants can get as tall and broad as about two feet. Some stay lower.

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.

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.