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Cool Season Floral Color

Calendula dislikes summer warmth and may not last completely through winter, but should last as long as marigold.

What was probably the last of the warm weather for the year really got the zinnias going again; but only for their leaves to become dusted with powdery mildew in the subsequent long cool nights. No matter how good the zinnia flowers still look, it is time for cool season annuals.

In mixed plantings, cool season annuals can be ‘plugged’ (as seedlings or small plants) or sown (as seed) among the warm season annuals so that they are ready to perform as the warm season annuals succumb to cooler weather. Of course in more uniform beds, warm season annuals will eventually need to be removed to make space for their cool season replacements.

Pansies and related violas are likely the two most popular cool season annuals. They fill in nicely as bedding plants or are nice components to mixed plantings. They perform best early in the season while the weather is still a bit warm, but should last until the weather gets too warm the following spring.

Primroses and Iceland poppies can take a bit more effort since they need ‘deadheading’ (removal of deteriorating flowers) to continue blooming. Primrose can also be hazardous to anyone who happens to be allergic to them, causing skin irritation comparable to that of poison oak! Some primroses are very brightly colored, while others are more subdued and elegant shades of pink and white. Iceland poppies are mostly pale shades of orange, yellow, pink and white on wiry stems.

Chrysanthemums, which are actually perennials, are the most variable of the cool season annuals, with a wild range of colors and flower forms. The varieties most popularly grown as annuals stay low and compact. Taller types make good cut flowers, but are not so practical for bedding. The related African daisies, which are incidentally similar to the ground cover of the same name, lack the variety of flower color and form, but are easier to grow; particularly as a perennial long after other cool season annuals are gone.

Calendulas are another simpler chrysanthemum relative that are more proportionate to typical annuals, since they get only a few inched deep. They would probably be more popular than they are if they provided more colors than their marigold like orange and yellow. Unlike chrysanthemums and African daisies, calendulas really are annuals, so do not last long into warm weather.

Red, white, pink and rosy pink flowers among rich green foliage can be provided by sweet William (dianthus). They not only tolerate a bit more shade than some other cool season annuals, but are also likely to survive sporadically as perennials where protected from warm exposure through spring and summer.

Stock is the best cool season annual for fragrance. It smells like carnations, but much stronger. Short varieties are good bedding annuals, and even better for mixed plantings. Taller varieties are great cut flowers.

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Fall Foliage Is Gaining Color

Minor chill can initiate major color.

Fall foliage is underappreciated here. It is not naturally prominent enough to suggest that it should be otherwise. Most native vegetation is evergreen. Most that is deciduous turns simple hues of yellow, without much orange or red. Some just gets shabby and brown as it defoliates with minor chill. Native vegetation does not represent total potential, though.

Contrary to common beliefs, local weather is not too mild for fall foliage to develop color. Only a few locally rare deciduous species need cooler weather for such color. Only a few deciduous species prematurely shed too much to develop their color for fall. Colorful fall foliage really could be more prominent within gardens than it is. It merely is not a priority.

Many home gardens here are within suburban or urban situations. Evergreen vegetation is therefore useful for privacy or to obscure undesirable views. Winter weather is not cold enough for evergreen shade to make it significantly colder. Some believe that deciduous vegetation is messier than evergreen vegetation. Some find it less appealing while bare.

Actually, evergreen foliage is generally more persistently messy than deciduous foliage. Although it sheds less abundantly, it does so more continuously through longer seasons. Some never stops shedding. Ultimately, the quantity of its detritus is at least comparable to that of deciduous foliage. Deciduous foliage sheds more profusely, but does so briefly.

Efficient shedding could be an incentive for deciduous vegetation. Sunnier conditions for winter could be another, whether or not it adds a bit of warmth. The color of fall foliage is obviously worthy of consideration also. Some types are more colorful than others. Some are more reliable than others. Ultimately, there is quite a bit of fall foliage to choose from.

Sweetgum, pistache and flowering pear develop the most exquisitely colorful fall foliage. Their color ranges from bright yellow, through orange, to deep red. Sweetgum is messier than the others, but only because it retains its fall foliage longer. Crape myrtle is smaller, but comparably colorful. Ginkgo is quite reliable for exceptionally brilliant yellow foliage, early in fall.

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Tree Work Will Be Less Stressful During Dormancy.

Only arborists can work on the big trees.

The taller trees are typically the first to admit that summer is finished and that it is now autumn. Perhaps because they are higher up and into the changing weather more than smaller plants that are sheltered and closer to the ground. Some trees are changing color nicely. Others are thinking about it. Evergreens are, . . . well, evergreen; so they may not seem to change so much. Nonetheless, autumn is here, and most plants will consequently be going dormant for the winter, or at least slowing down a bit.

For many trees and other plants that need to be pruned, the next few months will be the best time for it. Because they are more or less dormant, they are not very aware of whatever procedures they are subjected to. When they wake up in spring, they simply adapt to the earlier pruning and start growing as if not much happened to them. Dormancy is like a natural anesthesia for trees and plants.

Conversely, the end of winter and beginning of spring is the worst time to prune many trees and plants because they are just emerging from dormancy, so are wide awake! If necessary, minor pruning done properly is generally tolerable, but should realistically be done either before or after that time. Maples, birches, mulberries and figs express their disapproval of late pruning by bleeding profusely, and sometimes for a long time.

Deciduous trees are most dormant by winter when their leaves have fallen off. Pruning them a bit earlier would probably be harmless, but deprives them of their colorful foliage. Maples, gingkoes, poplars and mulberries typically defoliate earliest. Oaks, elms and sweetgums (liquidambars) take their time, holding onto their leaves until they get knocked out by wind and rain. Oaks and elms are not very colorful anyway. Sweetgums though can look too good to get pruned late into winter!  

Arborists are physicians of trees, so can prescribe recommended pruning and maintenance procedures. Many trees, like Chinese elms, fruitless mulberries and willows, need more attention than others. Austrian black pines and Eastern redbuds are not so needy. Blue spruces that are allowed to remain branched to the ground and have enough space around them may never need a visit by an arborist.

Regardless of how much attention any particular tree needs, when it develops a problem that is out of reach, it should be assessed by an arborist, and hopefully pruned accordingly. Because trees are the most substantial features of the landscape, and can develop worse problems if not maintained properly, it is imperative to procure the services of qualified arborists; and not trust such important tasks to a gardener or anyone who can find a chain saw and pick up. Fortunately, certified arborists can be found at the website of the International Society of Arboriculture (ISA), at www.isaarbor.com.

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Spring Bulbs Benefit From Vernalization

Spring bulbs vernalize with winter chill.

Spring bulbs obviously bloom for spring. Less obviously, they vernalize with winter chill. They are seasonable about now because this is when they should get into their gardens. Many prefer to be interred into their shallow graves by Halloween. Many can wait as late as New Year’s Day. If too much later, some may not experience enough chill to vernalize.

Planting spring bulbs can be ungratifying because there is nothing to see afterward. After all, they are dormant at the time. They lack foliage or any other parts to extend above the surface of the soil. They seem to remain inactive until they bloom as winter succumbs to spring. However, between now and then, they will secretly reset before resuming growth.

Vernalization is how many spring bulbs finish their previous season and begin their next. They know that it is winter after they experience a particular duration of a particular chill. By then, they should have finished all growth of the previous season. Afterwards, all new growth and bloom is for the next season. It is how they know to bloom on time for spring.

Dutch iris, freesia, ranunculus, anemone and common narcissus do not need much chill. Tulip, hyacinth, crocus and a few narcissus and daffodil do. Some bulbs that benefit from it get a prechill treatment before coming to nurseries. Prechilled tulip and hyacinth bulbs are sadly unlikely to bloom after their first year. They prefer more chill than they get here.

Otherwise, many spring bulbs are supposedly reliably perennial. Naturally, actual results may vary. Anemone can survive for many years, but might bloom only rarely. Ranunculus may be less perennial, but may also bloom better while it survives. Dutch iris and crocus are unpredictable. Freesia and simple varieties of narcissus are more reliably perennial.

Technically, some spring bulbs are not bulbs. Ranunculus and freesia, for example, grow from corms. Nonetheless, almost all spring bulbs bloom only once annually. Succession planting can prolong bloom. It provides subsequent phases to begin bloom as preceding phases finish. However, phases of reliably perennial bulbs synchronize after first bloom. Summer bulbs and bulb-like plants are seasonable later.

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Vines Are Aggressive

Grapevines need to be tamed.

So many of the vines that we enjoy in our gardens might not be so appealing if we knew how they behave in the wild. Many of their characteristics that are often practical in garden situations are detrimental to neighboring plants in natural settings. If they can get away with it, vines can be just as brutal in our own gardens.

Creeping fig is perhaps the most brutally aggressive of vines. Like many other vines, it exploits trees for support. While it reaches the top of the trees, it wraps the tree trunks with a grafted network of stems that expands as it grows, literally strangling the trees that gave it support. By the time the supporting tree trunks decay, the creeping fig has developed its own self supporting trunk. Algerian and English ivies can do the same.

Fortunately, these vines rarely get such opportunities in garden situations. Nonetheless, they need to be kept out of trees that might otherwise get overwhelmed. Since they attach to the surfaces that they climb by aerial roots, they should not be allowed to climb onto painted surfaces, stucco, or anything else that they can damage.

Boston ivy supports itself by holdfast disks, which it leaves on everything that it gets a hold of. If the vines get removed to paint a wall, the disks remain. Like creeping fig and the ivies, Boston ivy, should therefore only be allowed to climb surfaces that are not likely to be damaged by its climbing techniques. Creeping fig and Boston ivy both happen to be quite practical for freeway infrastructure and sound-walls, but are difficult to accommodate in tame urban landscapes.       

Wisteria is another very aggressive vine that can overwhelm small trees and shrubbery, but lacks aerial roots. It instead climbs by twining stems, which are safer for painted surfaces, but can constrict and crush light trellises, wooden shingles, lattice or anything else that that wrap around. It is certainly worth growing, but needs adequate support.

Bougainvillea and climbing roses do not climb on their own, but instead produce ‘scrambling’ canes that shoot upward and then lean onto their surroundings for support. If grown as vines, they need to be fastened to their support. If not pruned back occasionally, they can get quite overgrown and shrubby. Most varieties that are popular now fortunately stay small and manageable.

Honeysuckle, potato vine, blue dawn flower, evergreen clematis, star jasmine and the various trumpet vines are more manageable, but are still moderately aggressive. Carolina Jessamine, lilac vine, mandevilla, and passion vine are among the more docile of vines, only outdone by the annual vines like annual morning glory and climbing nasturtium.   

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Shedding Foliage Often Precedes Defoliation

Shedding foliage will eventually get messy.

Indian summer is more typical here than not. As usual, the weather cooled somewhat as summer finished, and then warmed again. It is now autumn by date, but still seems to be summer by weather. This might confuse some vegetation, although some is familiar with this pattern. Some vegetation reacts by shedding foliage prematurely, prior to dormancy.

Prematurely shedding foliage is not the same as defoliation of deciduous species. Many of the species that exhibit such response to the weather are evergreen. More importantly, both evergreen and deciduous species do it prior to autumn dormancy. Also, they do not defoliate completely. There will be enough deciduous foliage for autumn foliar color later.

In the wild, prematurely shedding foliage is common among native California sycamore. It is a natural response to minor desiccation from any combination of aridity and warmth. It is as random as weather. Anthracnose is a foliar disease that might cause more severe defoliation earlier. Either type of shedding may be visually unappealing, but is harmless.

Actually, premature shedding foliage is common among many regionally native species. It helps them survive within chaparral climates. Although not a problem in the wild, it can be messy in or adjacent to refined landscapes. Both coastal redwood and coast live oak are notoriously messy. Yet, both species are evergreen and endemic to coastal climates.

Some exotic species from various climates can exhibit prematurely shedding foliage too. Species from other chaparral or desert climates are naturally proficient with the process. Species from less arid climates learn fast. It can be stressful for some of them. Daylength assures them that shedding is now safe. However, warmth that necessitates it might not.

Various species react variously to the various causes of premature shedding. That is too many variables. Simply, shedding is different every year because the weather is different every year. Eastern redbud and birchs that are exceptionally messy now may not be next year. Japanese maples happen to be shedding a bit less this year than they typically do.

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California Native Plants

(Some of the information within this article is very outdated because the article was recycled from several years ago.

Valley oak, as well as coast live oak, were the two most common native non-riparian tree species of the Santa Clara Valley.

Bringing nature to the garden is generally very unnatural. Before urban development of the Santa Clara Valley, there were a few valley and coast live oaks spread out sporadically over open chaparral, with a few sycamores, maples and other riparian specie only in the creeks and Guadalupe River that run through it. There are vastly more trees and plant life here now than there ever have been, and specie from every region of the world. Since exotic (non native) plants are from other climates and soils, they require unnatural accommodations, such as watering and fertilizers, to keep them happy.

The most natural gardening is done with native plants, which are naturally adapted to local climates and soils. Natives are not as demanding of amendments, fertilizers or pesticides as some exotic plants are, since they know how to get they want with the local resources available. Because most are satisfied with natural rainfall, they do just fine with minimal watering (once established).

All sorts of native plants will be available at the Native Plant Sale at Hidden Villa Ranch in Los Altos Hills in only ten days on October 16, from 10:00 a.m. to 3:00 p.m.. Deergrass, monkey flower, redbud, blue-eyed grass, buckwheat, sedums and native lilies and orchids will all be there and accurately labeled. Volunteers from the California Native Plant Society will be available to talk about alternatives to law, including native perennials, shrubs, wildflowers and grasses. Books about native plants, as well as posters and note cards featuring native plants will also be available.

From 1:00 to 2:00 p.m., Stephanie Curtis of Curtis Horticulture will give a free hour lecture about tips for planting success and maintenance for natives. Admission is limited to 25 people though, first come first served. 

Hidden Villa Ranch is located at 26870 Moody Road in Los Alton Hills, two miles west of the Moody Road and El Monte Road interchange at Highway 280. Plant selection is best early in the day. All sales must be by cash or check, since credit cards are not accepted. It helps to bring boxes to carry purchased items. More information can be found at www.cnps-scv.org or cnps_scv@yahoo.com or by telephoning 650 – 260 3450. Incidentally, autumn is a good time for planting, since the warmest part of summer is over, and the rain will arrive soon to settle soil around the roots of newly planted plants.  

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Banana Trees Actually Produce Bananas

Banana trees provide boldly lush foliage.

Banana trees, much like palms, arboriform yuccas and cordylines, are herbaceous trees. They develop no secondary xylem, or wood. What seems to be trunks are pseudostems, which are just leaves in very tight bundles. These pseudostems grow from subterranean corms, which can grow rather big. Each pseudostem is monocarpic, so dies after bloom.

Although they are very easy to grow, banana trees are not very popular. They can be too easy to grow, and become overwhelming. In some climates, frost can ruin their foliage for part of the year. In some exposures, their foliage can get shabby from wind. Some expect generous and frequent applications of fertilizer. All want generous and frequent irrigation.

These characteristics are contrary to growing banana trees merely for appealing foliage. Realistically, that is what most are for. Those of the Ensente genus are fortunately easier to maintain, but fruitless. Their lushly huge leaves are spectacular, relatively durable and generate much less debris. However, after a few years, they die without generating pups.

Banana trees of the Musa genus generate fruit, although some are primarily ornamental. A few produce delightfully colorful fruit that is too small, seedy or starchy to be palatable. Musa are more pervasive although less popular than Ensente. While Ensente come and go, Musa are reliably perennial. Several produce enough pups to potentially be invasive.

Musa, unlike Ensente, therefore develops colonies of a few to many pseudostem trunks. A few new trunks can replace each old trunk faster than they can deteriorate after bloom. Removal of deteriorating old trunks promotes growth and fruiting of new trunks. So does culling of congested new trunks. They propagate very easily by division with intact roots.

Because banana trees are tropical, they are unfamiliar with the seasons here. They grow fast with warmth but very slowly without it. They bloom randomly though. Flowers that try to bloom during autumn may stagnate long enough to rot through winter. Late fruit can do the same. Fruit that begins to develop early is much more likely to finish prior to autumn. Some cultivars develop faster.

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The Stakes Are High.

Binding nursery stakes should be replaced with less restrictive staking and straps.

            After all the unnatural things that plants must endure to get into gardens and landscapes, it is amazing that they are as happy as they are to perform. Most come from very different climates, only to be grown in artificial nursery conditions while confined to containers, then get shipped to other different climates where they get planted in foreign soil, and are expected to adapt. Nonetheless, they still provide flowers, fruit, vegetables, shade and all that we expect from them!

             Trees must suffer even more. Their lower growth that should enhance trunk growth gets pruned away prematurely. Trunk growth is further inhibited by staking, which is ironically necessary for straight and vertical trunks. Fortunately, most trees recover from these procedures.

            Weaning trees off their original stakes can take a bit of work though. Because of their lanky trunks and disproportionately bulky canopies, most new trees need help to stand up against the wind. Except for palms and a few stout trees that are allowed to keep their lower growth, such as redwoods and some pines, almost all trees need to be staked when planted. However, their trunks should not be bound so tightly that they rely on their stakes for support.

            Stakes that are proportionate to new trees should be installed as the trees get planted. They should ideally be a few inches away from the trees and stand as high as necessary to provide adequate support. A small tree (such as #5 or 5 gallon) may need only a single stake. A larger tree (such as #15 or 15 gallon or larger) typically needs two stakes on opposite sides. The original ‘nursery stakes’ that are bound to the trunks should then be removed as trees then get tied to their new stakes. Trees will need to be supported during this process.

            Trees like red maple or flowering pear that have stronger trunks that do not bend much may only need to be tied at the top, just above their lowest limbs. Most trees have more flexible trunks though, so also need to be tied lower down, generally about halfway between the ground and the top tie. Very flexible trees, like many eucalypti, may need to be tied in even more places. Since there are rarely branches on the trunks to keep the lower ties from sliding downward, the ties may need to be nailed to the stakes.

            Ties should wrap around the trunks and cross over before wrapping around the stakes; in a ‘figure 8’ pattern. This limits abrasion from the stake against the trunks. Ties made from recycled tires with bailing wire at the ends are ideal and easiest. For larger lodgepole stakes, recycled tire ties without wire can be nailed directly to the stakes. Ties should only support trees as they blow away from their stakes or bow from their own weight, but should not bind them firmly to the stakes. This way, trees need to become able to support their own weight.

            As trees mature and no longer need support, stakes and ties should be removed. Stakes and ties that get left too long can actually interfere with trunk development, and cause significant damage and abrasion as trunks expand.

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Palm Trees Deserve Special Accommodation

Palm trees are bold landscape features.

Palm trees qualify as trees only because of their size and form. The most familiar sorts here develop trunks, and many grow quite tall. The smallest houseplant palms can grow as tall as dwarf citrus trees. Mexican fan palm can grow nearly a hundred feet tall. Palms are monocots, though, so are not actually woody. Technically, they are herbaceous trees.

Palm trees share this distinction with several other herbaceous trees. Banana tree trunks are just tightly rolled leaves. Tree ferns elevate their growth on roots that grow downward through rotting stem growth. Neither banana trees nor tree ferns can generate branches. Sago palms, cabbage trees and arboriform yuccas develop branches, but without wood.

Some palm trees develop a few trunks, but almost none develop branches above grade. Date palms can, but rarely branch. Doum palms typically branch, but are extremely rare. Any other branching palm trees are either aberrative or not really palm trees. Palm trunks do not grow wider as they grow taller. Adventitious roots can become buttressed, though.

All palm trees are evergreen, with either pinnate or palmate foliage. Feather palms have pinnate foliage. Each leaf consists of a central rachis that supports many narrow leaflets. Fan palms have palmate foliage. Each leaf radiates from the terminus of its stout petiole. Both basal leaflets of feather palms and petioles of fan palms are typically horridly spiny.

Since palm trees can not branch, they are not conducive to pruning to direct their growth. Their big but solitary terminal buds grow only upward and maybe away from shade. Any that reach high voltage cables can not go around, so necessitate removal. Clearance for overhanging obstacles is a major consideration for situating new palms. Some grow fast.

While unconducive to directional pruning, most palm trees benefit from grooming. Only a few shed their old foliage naturally. Most get shabby by retaining it. Many, particularly fan palms, eventually become combustible or infested with rodents. However, some may be visually appealing with neat beards of old foliage. Only arborists can groom large palms.