Pansy is one of the most familiar of cool season annuals.
All sorts of shades and combinations of yellow, orange, red, purple and blue, as well as white and monochromatic black can be found among the many varieties of pansy, Viola X wittrockiana. Pansy flowers are mostly about two inches wide, with a pair of overlapping upper petals, a pair of side petals and a single lower petal. Even though they stand only about half a foot high, flowers hover slightly above the foliage.
Here where winters are so mild, pansies get planted in autumn to bloom through winter, and then get replaced with warm season annuals in spring. They can survive through summer, but do not perform so well while weather is warm. Deadheading (removal of deteriorating flowers) promotes continual bloom. Related violas typically produce more profuse but smaller flowers, which are actually physiologically different.
Petunia must eventually be replaced, even if the tips of deteriorating stems continue to bloom.
Here in the mild climates on the west coast of California, the difficulty of getting new cool season annuals into the garden to bloom through autumn and winter is not selecting, procuring and installing the new annuals. It is the removal of the warm season annuals while they are still blooming and looking so good! Knowing that planting new annuals sooner than later will get them an earlier start is not always much consolation.
Pansy, viola, primrose, snapdragon and alyssum are probably the most familiar and favorite of cool season annuals, and are often allowed to bloom late into spring when they probably should be replaced by warm season annuals. Alyssum easily naturalizes, and can actually bloom all year in coastal or cool areas. Snapdragon are probably the most difficult of these favorites to grow, since they so often get infested with rust, a common fungal disease that proliferates where winters are mild.
Cornflower (bachelor’s button), stock, Iceland poppy, sweet William and calendula are probably a bit less popular only because they are not so conducive to mass planting as bedding plants. Cornflower and stock get taller than they should for beds, although they look great behind beds; and stock is excellently fragrant. Iceland poppy, sweet William and calendula do not often grow uniformly enough for large beds; and calendula does not offer much variety of color beyond shades of yellow and orange. Yet, all are great in mixed plantings.
Ornamental cabbage and kale are grown for their colorful foliage instead of flowers. Cabbage may be a bit more colorful; but kale can provide more variety of foliar texture. Because they form such bold rosettes of foliage that do not blend into each other like other bedding plants do, they are more often grown as narrow borders or in small mixed plantings instead of in broad uniform beds.
The ornamental potential of both Swiss chard and parsley should not be denied. Swiss chard has distinctively ruffled and glossy foliage that can be dark green or deep burgundy. Their prominent midribs and veins can be even more colorful with shades of greenish white, yellow, orange, red or pale purple. Parsley is rich green, with full, intricately textured foliage that happens to look quite sharp with white alyssum. The main problem with these two cool season vegetables is that their appearance can be compromised if they get eaten.
The Maya cultivated marigolds long before the French. After all, the ancestors of modern French hybrid marigolds, Tagetes patula, are endemic to Mexico and Guatemala. French horticulturists merely developed the hybrids that are now most popular. The largest might grow a foot high and wide. Otherwise, almost all grow lower as compact bedding plants.
Although many varieties of French hybrid marigold are available, their floral color ranges only through yellow, orange and red. Ruddy brown is merely dark orange. Creamy white is merely very pale yellow. Combinations of color within this minimal range are amazing nonetheless. White is rare only because richer traditional colors remain so very popular.
French marigolds are technically warm season annuals. With frequent deadheading and grooming, they can bloom from spring until frost. However, since they perform best while young, they are more popular as a shorter term annual. They often replace warm season annuals that finish a bit early, while the weather is still too warm for cool season annuals.
Cool season vegetables will replace warm season vegetables during autumn. Also, cool season annuals will replace warm season annuals. Neither simple task is easy for warm season plants that continue to perform too well to remove. Conversely, some finish early. Autumn annuals may compensate until cool season annuals become more seasonable.
Summers here are long, dry and somewhat warm. Even petunias and other annuals that enjoy warmth and tolerate aridity may not want to perform for so long. Without occasional grooming, they can get shabby by late summer. The recent unusually warm weather only accelerated the process for this year. Summer weather might continue into early autumn.
Consequently, it may still be a bit too early for some favorite cool season annuals that do not appreciate arid warmth. Pansies can get scrawny and lay low in response to warmth. Ornamental cabbage and kale is likely to bolt (general floral stalks) after exposure to too much warmth. Such annuals perform better or for a longer season after summer warmth.
This is why autumn annuals are so popular. They replace tired warm season annuals by the end of summer, and bloom until the weather is cool enough for cool season annuals. Autumn annuals generally bloom for shorter seasons than warm or cool season annuals, but most last until frost or significant rain. After bloom, a few are actually perennial plants.
Chrysanthemums and marigolds may be the most familiar of autumn annuals. Marigolds are actually warm season annuals that can perform just as well during spring or summer. Late installation allows late performance, which can continue until frost or sustained rain. Chrysanthemums are actually perennials, so can grow and bloom again for next autumn.
Celosia and alyssum, like marigold, are warm season annuals that perform late after late installation. Sweet William is a cool season annual that, after early installation, begins to perform earlier. Several types of aster naturally bloom late in summer or early in autumn. Even if nasturtium already succumbed to warmth, fresh seedlings may perform until frost. Old plants, prior to deterioration, could have provided seed, albeit feral, for their own replacement.
Toadflax really does look like baby snapdragon, which is its other common name. The tiny, half inch wide flowers are similarly bisymmetrical, and arranged in small trusses, although the diminutive leaves are distinctively narrow.
Common toadflax, Linaria maroccana, which is actually less common than the name implies, gets about one and a half to two feet tall and about half a foot wide. Two toned flowers bloom in summer in shades of pink, purplish pink, purple, blue, very pale yellow or red with yellow. ‘Northern Lights’ adds shades and bicolor combinations of yellow, orange and red to the mix. The more common ‘Fantasy Hybrids’ get only about half as tall and perhaps slightly wider, with earlier and slightly larger flowers in shades of yellow, blue, pink and bright pink, as well as white, mostly with slightly yellow throats.
Toadflax is a summer annual, but does not like to be too exposed to roasting heat and glare. If grown from seed, it should be sown as soon as possible after the last frost to get an early start.
Many popular annual bedding plants have potential to be perennial if they get a chance. Cyclamen commonly perform as a cool season annual, only until replacement with warm season annuals. However, after summer dormancy, their tubers can generate foliage and bloom again for several following winters. Replacement is just easier than maintenance.
Real annuals complete their entire life cycles, from germination to dispersal of seed and finally death, within a single year. Biennials generate vegetative growth through their first year, and then disperse seed and die during their second year. Perennials perform for at least two years, whether or not they get any opportunities to do so within home gardens.
Home garden culture complicates this classification though. Those who enjoy gardening expect perennial plants to reliably perform for many years or indefinitely. Many perennial plants do so with only minimal intervention. Some are self-sustaining, and might seem to naturalize. That may be why so many smaller or less vigorous types classify as annuals.
Another qualification of perennial plants is that they lack woody stems and roots. In other words, they are herbaceous. Palms and species of Yucca that develop trunks classify as perennial plants also, but for simplicity, the larger types are herbaceous trees. Generally, perennials are terrestrial. A few are epiphytic (live in trees) or lithophytic (live on stones).
Although several perennial plants can survive indefinitely here without intervention, most perform better with some degree of attention. Most ferns are neater if groomed to remove deteriorated fronds. Many grasses benefit from severe shearing during winter. African iris blooms better in response to regular deadheading to remove developing seed capsules.
Perennial plants are very diverse. It is impossible to generalize about their maintenance. One commonality among many is that they multiply. Lily of the Nile can produce so many individual shoots that it can eventually become too congested to bloom. Division of such shoots every several years or so promotes bloom, as well as propagates more plants for elsewhere in the landscape.
The bright colors and patterns of blanket flower, Gaillardia, resemble those of blankets made by native American Indians. The daisy flowers are typically two different shades of red, orange, yellow, brown or yellowish white. Not many varieties bloom with single colors. Taller varieties can get almost two feet tall, with slender but sturdy stems that are good for cutting. The narrow leaves are mostly basal, so do not crowd bloom.
The more popular varieties of blanket flower are perennial. Healthy plants can slowly get quite broad, and can self sow their seed to spread a bit farther. Annual varieties can not get as broad, but often self sow more efficiently than perennial types do. Once it gets growing, blanket flower does not need much water. However, regularly watered plants are already blooming. Modestly watered plants wait until summer.
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.
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.
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.
Tony Tomeo 