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Cool Season Vegetables Eventually Replace Warm Season Vegetables

Peppers do not grow in cooling autumn weather.

Just as warm season annual flowers that bloomed through spring and summer get removed to relinquish their space to cool season annuals, summer vegetable plants need to vacate the garden for cool season vegetables. Fortunately, removing vegetable plants is not as unpleasant as removing the pretty flowers might have been, because most have finished producing whatever it is that they were grown to produce.

Besides, cool season vegetables are even cooler than warm season vegetables, since some have distinctive foliage that is appealing beyond the vegetable garden, in borders, pots and mixed plantings, out in the landscape. Swiss chard is a striking foliar plant, whether it gets eaten or not. The outer leaves can get eaten without compromising the appeal of the inner leaves that continue to grow and fluff outward to replace them. Arugula, kale, mache, loose lettuce (non heading) and collard, mustard and turnip greens do the same.

This ability to function in more places in the landscape is a definite advantage since cool season vegetables are not quite as productive as warm season vegetables are. They would certainly like to be as productive, but grow slower through cool weather.

Most cool season vegetables should be sown into the garden as seed. Root vegetables, like beet, carrot and radish, might be available as seedlings in cell packs, but do not recover very well from transplanting. Besides, seedlings of such plants in cell packs are either too abundant and crowded, or to sparse to produce much. Leek, loose leaf lettuce and most of the greens likewise grow best if sown as seed in rows instead of planted in tight clumps as they are grown in cell packs.

Only greens that are grown as individual big plants, like chard, kale and collard green, can be as productive from cell pack seedlings as from seed. However, each cell pack produces only six plants, maybe with some extras. A package of seed costs about the same, but contains more seed than most gardens can accommodate.

Actually, the only cool season vegetables that might be more practical to grow from cell pack seedlings than from seed are broccoli, cauliflower, cabbage and Brussels sprout. These vegetables grow as even larger plants, so minimal quantities, like one or two or perhaps three cell packs, are sufficient.

Like so many of the warm season vegetables, many cool season vegetables should be planted in phases every two to four weeks to prolong harvest. By the time the first phase finishes, the next phase will be ready. The frequency of phases depends on the growth rate and duration of production of the particular plants. For example, chard has a long duration of production, so does not need many phases.

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Cool Season Annuals Eventually Replace Warm Season Annuals

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.

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Autumn Annuals Transition From Summer

Warm colors bloom as weather cools.

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.

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Succulents Are A Diverse Group

If Agave are succulents, are closely related Yucca also succulents?

There really is no way to neatly classify succulents. Many are spiny cacti with fleshy stems without recognizable foliage. Others are euphorbs (related to poinsettias) that may resemble cacti, or may instead have fragile leaves on fleshy stems. Aloes and agaves have bold rosettes of fleshy leaves that obscure their wide basal stems.

The most familiar succulents are small docile perennials, like the many varieties of jade plants and iceplants. Some are flowering perennials like begonias. A few are even grown as annuals, like busy Lizzie (impatiens).

So what do succulents have in common? Well, that is a good question that is open to interpretation. Most would agree that succulents have some sort of fleshy succulent parts for storing water through dry weather. These succulent parts are most often leaves or stems. Yet, yuccas, dracaenas and ponytail palm that are no more succulent than palms, are considered by many to be succulents like related aloes and agaves.

Many succulents are remarkably easy to propagate vegetatively (without seed). Most aloes, some agaves and many yuccas produce pups, which are basal shoots that can be separated as new plants. Agaves that do not produce pups while young will likely produce many pups after they bloom and begin to deteriorate. (Individual rosettes die after blooming.)

Despite the nasty spines that make them difficult to handle, cactus that produce multiple trunks can likewise be divided. Cactus can alternatively be propagated as large cuttings; but because they are so fleshy, should be left out for their cut ends to dry and ‘cauterize’ somewhat before rooting. Many euphorbs behave much like cacti, but are even more hazardous to handle because of their very caustic sap.

The majority of small succulents, like the many jade plants and iceplants, are notoriously easy to propagate by cuttings.

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Cole Vegetables Are Cool Vegetables

Mustard greens are cultivated and naturalized.

September began with the warmest weather of the year. Such weather is not uncommon for late summer here. It can happen as late as early autumn. Still, it can be disconcerting while weather should be cooling. Cool season vegetable plants that are technically now seasonable dislike such warmth. Cole vegetables are particularly responsive to weather.

Cole vegetables are within the Cruciferae family, which is alternatively the Brassicaceae family. They therefore also classify as crucifers or brassicas. They include various forms of broccoli, cauliflower, cabbage, collard, kale, kohlrabi, mustard, turnip, radish, arugula, rutabaga and Brussels sprouts. As variable as they are, several are of the same species.

Broccoli and cauliflower are floral vegetables, since their primary edible parts are bloom. Brussels sprouts, cabbage, collard, kale, arugula, mustard greens and turnip greens are foliar. Turnip, radish and rutabaga are roots. Kohlrabi is a distended stem. Mustard seed, which is a seasoning instead of a vegetable, is the only common fruiting cole vegetable.

Therefore, unlike most warm season vegetables, cole vegetables should not fruit or go to seed. Broccoli and cauliflower only begin to bloom, but do not finish prior to harvest. This is why most cole vegetables are cool season vegetables here. Warmth stimulates bolting and bloom, which ruins flavor and palatability. Cool weather prolongs vegetative growth.

Contrary to the implications of recent weather, cool season vegetables, including several cole vegetables, are seasonable. This is the time to sow seed for turnip, radish, rutabaga and other cool season root vegetables directly into the garden. Transplant of seedlings is disfiguring to roots. Weather should be cooler by the time new seedlings start to develop.

Arugula, turnip greens, mustard greens, collard, kale and kohlrabi likewise develop most efficiently from seed. However, transplanted seedlings can be adequately productive too. Because only a few broccoli, cauliflower, cabbage and Brussels sprouts plants are likely sufficient, cell pack seedlings are likely more practical than seed. Since they are already growing, they can get planted a bit later.

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Conformity Is No Simple Task

Patching bald spots within Iris moss with Scottish moss might look . . . odd.

A combination of modern horticultural apathy and too many choices was probably the demise of conformity in home gardens. Formal hedges or even informal screens of several of the same plants are nearly obsolete. Ironically, long and low barrier hedges and so called ‘orchards’ of identical trees planted in regimented rows or grid patterns have become common in large landscapes in public spaces.

Those of us who still crave formal hedges, paired trees or any such symmetry in our home gardens must be more careful with the selection of the plants that need to conform than would have been necessary decades ago when there was less variety to complicate things. It is just too easy to get different varieties of the same plant. Only plants with matching cultivar (cultivated variety) names will necessarily match. (Yet, on rare occasion, even these are inaccurate.) For example, ‘Emerald’ arborvitaes will match other ‘Emerald’ arborvitaes, but will not match ‘Green splendor’ arborvitae, no matter how they resemble each other in the nursery.

Plants that are identified by their characteristics instead of by cultivar name are riskier. Blue lily-of-the-Nile could be any one of many different cultivars with blue flowers. It is therefore best to obtain all lily-of-the-Nile for any matching group from the same group in the same nursery at the same time. What will be available next week may actually be a different variety with a different shade of blue and different foliar characteristics. Nurseries bring stock in from so many different growers.

Adding new plants to replace those that have died within established hedges or streets flanked with the same trees can be particularly difficult, especially if the old varieties are no longer available. The old fashioned yellowish Japanese boxwood that was so common for small hedges in the 1950’s has not been common in nurseries for several decades. Replacement plants are darker green. Some are even compact cultivars or different specie like English boxwood. When lined up and shorn together, they make ‘calico’ hedges.

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White Bloom Brightens Cool Shade

White might be an acquired taste.

White and black are supposedly opposites. White is a combination of all wavelengths of visible light. Black is a complete absence of such light. In other words, white is a mixture of all colors, while black is the absence of any color. This seems contrary to the common perception of white as a complete lack of color, and black as a complete mix of all colors.

It actually makes sense. The two really are opposites of both each other and themselves. This is about horticulture though, rather than physics. Black is quite rare as a floral color. White is not. The vast majority of flowers do not rely on color to attract pollinators, so are green or brown. Otherwise, most other prominent flowers in many ecosystems are white.

Like inconspicuous green and brown flowers, many white flowers exploit wind more than pollinators. Such flowers are generally profuse, but mostly diminutive and unimpressive. Other flowers that appear to be white utilize infrared or ultraviolet colors that are invisible to people, but colorful to nocturnal pollinators. Some of them are pale during the daytime.

Otherwise, the majority of white flowers that are popular within home gardens are just as flashy as their nonwhite associates. For many types of flowers, such as roses, camellias, azaleas and the countless types of annuals, floral color is more variable than floral form. White is simply another option for color. It serves various specific and practical purposes.

While brightly colorful annuals are appealing within sunny and exposed situations, white flowers brighten darker situations. They contrast nicely with dark green foliage and richly colorful flowers. Petunias that might be a bit too deep purple for a particular situation can mix with similar but white petunias to be more harmonious. White can be a buffering tint.

Colors should preferably be appropriate to their particular applications. Such selection is more aesthetic than horticultural. Some plants, such as gladiola, petunia, calla, oleander and some lily, excel at white bloom. Bougainvillea and crape myrtle excel at richer color.

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Deadheading Conserves Resources

If not deadheaded, roses can put a lot of resources into production of seed and hips.

It takes quite a bit of effort for flowers to bloom. It takes even more effort and resources for pollinated flowers to produce seed and the fruiting structures that contain the seed. If the seed of certain aggressive plants get dispersed, we need to put even more effort into pulling up the seedlings. It just never seems to end!

Removal of deteriorating flowers, commonly known (even by those of us who missed that generation) as ‘deadheading’, can eliminate so much of this extra work. Not many plants benefit from deadheading; but most that do are really grateful for it. Others that do not care one way or the other simply look better without their deteriorating flowers.

It is of course impossible to deadhead large flowering trees or vast areas of ground cover. Regularly shorn hedges should never need deadheading because they never get the opportunity to bloom or develop fruit. Plants that are appreciated for the ornamental quality of their fruit should of course not be deadheaded.

Most roses get deadheaded as they bloom because the development of their fruiting structures, known as ‘hips’, takes enough resources to compromise subsequent bloom. Removal of these hips therefore promotes bloom. Only the few types of roses that are grown for their showy hips should not get deadheaded. Phlox, daisies, zinias, dianthus and all sorts of plants with long continual bloom seasons likewise benefit from deadheading.

Some types of iris that produce seed perform better with deadheading, not because they will bloom again during the same season, but because they can divert resources to vegetative growth (like rhizomes and foliage) that will sustain bloom during the following year. Most bearded iris (that do not produce seed) and lily-of-the-Nile do not seem to care if they get deadheaded, but are generally more appealing without their finished flower trusses.

Four o’ clocks can not be deadheaded without also removing developing flowers, so can only be allowed to bloom and throw their invasive seed all over the garden. It is easier to pull their seedlings later. We have a bit more control over crocosmia. Even though they do not need to be deadheaded, they are less invasive and more appealing without their scraggly brown stalks and seed capsules.

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Pups Of A Horticultural Nature

Pups are copies of their parents.

Pups of the most familiar type are canine. Most are puppies of domestic dogs. Some are foxes or wolves. A few are seals, otters or various other animals. Garden variety pups do not get much consideration though. They develop into new progeny of plants rather than animals. Unlike animal pups, they are genetically identical clones of their single parents.

Pups of the horticultural sort generally develop from subterranean stems, such as corms, tubers or rhizomes. Most emerge from formerly dormant buds. Some grow adventitiously from roots. Pups appear as basal sideshoots against or close to their parent plants. They efficiently disperse their own roots to eventually survive as new and independent plants.

Most plants that produce pups are perennials. Some are so proficient with the technique that they grow into substantial colonies of genetically identical clones. For some, it is the primary method of replication. They actually prefer to replicate vegetatively than by seed. Some trees and woody plants do the same, but their clones lack the same classification.

For many perennials, propagation by division is merely the separation of pups from their parent plants. Most types of banana trees eventually generate a few surplus pups. Some types generate an abundance of pups to share with anyone who wants them. Separation of their pups is very similar to division of the smaller rhizomes of canna or lily of the Nile.

Individual rosettes of various species of Agave and a few terrestrial species of Yucca are monocarpic. In other words, they die after blooming only once. However, instead of dying completely, most generate several pups prior to bloom. Some produce pups excessively! Such pups can be difficult and hazardous to separate, but can replace their own parents.

Mediterranean fan palm is one of only a few palms here that generates pups. That is why it develops multiple trunks. Surplus pups can survive separation to grow as distinct trees. However, because of their densely fibrous roots, separation of intact pups can be difficult or impossible. Sago palms, which are not actually palms, are more compliant to division, even for rootless pups that develop on their stout trunks.

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Delay Some Gardening Between Seasons

Plants are still going to seed.

For gardening, this is one of those in between times of year, when summer chores are under control, but it is a bit too early for much of the work that will need to be done in autumn. Automated watering systems have already been adjusted for the longest and warmest days of summer, so will only need to be adjusted the other way as days eventually get cooler and shorter. Growth of most plants slows; and some of the plants that will later be the earliest to show fall color begin to fade from bright green to paler green.

The last of the summer fruits should be gone, leaving the trees that produced them looking somewhat tired. The weight of large fruit, particularly peaches, might have pulled stems downward where they may now be obtrusive. Pruning a few minor stems should not be a problem. However, trees are still too vascularly active for major pruning. That needs to wait for dormant pruning while trees are bare in winter.

A few plants with sensitive bark are susceptible to sun scald if pruned to expose too much bark on interior stems while the sun is still high and warm. This is not so likely to be a problem if pruned during winter because the sun is lower and cooler, and foliage grows back before the following summer. Actually, that is why English walnut and various maples are able to defoliate during winter, even though their smooth bark needs to be shaded.

Pruning of plants that are potentially sensitive to frost should likewise be delayed. Otherwise, pruning is likely to stimulate development of tender new growth that will be even more sensitive to frost during winter. Besides, new growth develops slower this time of year, so plants look freshly pruned for a longer time than if pruned late in winter, just prior to spring.

Some types of pittosporum are more susceptible to disease if pruned in late summer or autumn because their open pruning wounds heal slowly and stay open to infection during rainy winter weather. However, slow recovery from pruning can be an advantage to formally shorn hedges that are not so sensitive to frost or disease, such as the various boxwoods, or glossy or wax privets. If shorn now, they might stay trim until spring.

The dried foliar remains of any summer bulbs that are finished blooming can now be plucked and disposed of. Gladiolus and montbretias that are still green can be deadheaded (pruned to remove deteriorated flower stalks), but should be allowed to turn completely brown before getting plucked. Watsonias are not so easy to pluck without also pulling up the bulbs, so should instead get their dried foliage pruned off.

Weeds outside of landscaped areas may not seem to be a problem, but many are now producing seed that gets blown into the garden. Even if such weeds do not need to be pulled, their flowers and seeding stalks should still be cut off and removed if possible.