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Sudden Limb Failure Jeopardizes Safety

Entire trees can also fall unexpectedly.

Windy weather sometimes breaks limbs from trees, or blows entire trees over. Evergreen trees are innately more susceptible to such damage than deciduous trees are. Wind can blow more easily through deciduous trees while they are bare through winter, when most wind occurs. However, deciduous trees are now more susceptible to sudden limb failure. 

Sudden limb failure, or spontaneous limb failure, is a result of gravity rather than of wind. It is actually more likely without wind, during mild or warm weather, particularly with high humidity. It consequently has potential to be more hazardous than limbs that blow down. More people go outside among trees during mild weather, and fewer expect falling limbs. 

Sudden limb failure occurs if limbs become unable to support their own increasing foliar weight. Warmth accelerates vascular activity, which sustains foliar growth. High humidity and a lack of wind inhibit evapotranspiration (evaporation from foliage), which otherwise helps to alleviate excessive weight. Developing fruit can also cause sudden limb failure.

In the wild, willows, poplars, sycamores, and perhaps a few other riparian trees regularly and naturally exhibit partial sudden limb failure. Limbs that fracture and sag onto soil, but remain partially attached to their original tree, can generate roots and grow as new trees. Although their strategy is practical for them, it is unacceptable within refined landscapes. 

Several native and exotic trees of chaparral climate are quite susceptible to sudden limb failure within or adjacent to irrigated landscapes. Since they are not accustomed to such abundant moisture, they overindulge. Mature wild trees are more likely to exhibit sudden limb failure after an unusually rainy and warm winter, or if rain continued late into spring.

All native oaks, particularly valley oak and coast live oak, are susceptible to sudden limb failure. So are Monterey pine and Monterey cypress. Carob, sweetgum, various elm and various eucalypti are exotic species that are notorious for such behavior. Evergreens are more unpredictable, since their new growth is less obvious among their lingering foliage. 

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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.

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Palms Are Very Distinctive Among Trees

Palms provide distinctively lush foliar texture.

Palms seem to exemplify the culture of California. However, only the California fan palm, which is also the desert fan palm, is native. All others are exotic. With its dwarf palmetto, Oklahoma has as many native palms as California. Furthermore, the California fan palm is only endemic within remote riparian ecosystems of the Colorado and Mojave Deserts.

Common date palms were likely the first of the many exotic palms in California. Spanish Missionaries imported them for date production during the Eighteenth Century. Although initially utilitarian rather than decorative, recycled trees from displaced orchards became popular for larger landscapes. Potentially messy fruit is minimal without male pollinators. 

Long before urbanization displaced date orchards, many other palms came to California merely because of their visual appeal. Some are large enough to be shade trees. Others can provide shade in groups. Many develop elegant trunks or sculptural form. Some stay relatively low or shrubby. All innately provide famously and luxuriantly evergreen foliage.  

Palms are most certainly appealing within appropriate situations. They are very different from other trees though. Like arborescent yuccas and cordylines, palms are ‘herbaceous trees’. Unlike yuccas and cordylines, and with very few exceptions, palms do not branch. Nor do their trunks continue to expand in width as they continue to grow in height above.  

Palms consequently spend their first few years widening their bases at ground level. Big palms, such as Canary Island date palm, likely require many years. Once their bases are adequate, developing palms ‘launch’ into vertical growth. Although palms do not branch, a few, such as Mediterranean fan palm, develop multiple trunks from their primary bases. 

Once palms launch, they grow only upward. They lean only to avoid shade, or if pushed by wind. It is impossible to direct their bulky but singular terminal buds around obstacles, such as utility cables. It is also impossible to contain their shade as they get high enough to shade adjacent areas instead. Many palms are spiny, so are difficult to prune properly, even while young and within reach.

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The Stakes Could Be High

Some unfortunate trees become so reliant on staking and straps that they are never able to support their own weight.

The irony of landscaping and gardening to bring nature closer to the home is that it is so very unnatural. Plant specie are imported from all over the world, grown in synthetic environments, and then expected to perform in unfamiliar climates and soils far from home. Most plants have been bred for optimal retail appeal at the expense of their natural adaptations.

Trees grown in nurseries need to be staked tightly to develop the sort of straight trunks that branch at just the right height to be marketable. In the landscape, trees need to be staked because they have become so dependent on the stakes that they grew up with. Eventually though, trees need to learn how to carry their own weight.

When new trees get planted and staked loosely with heftier stakes that stand up to wind, old tightly bound nursery stakes should be removed since the tight binding interferes with trunk development. By the time trees gets planted, the nursery stakes are probably nearly rotten through at the ground anyway. The new heftier stakes should not hold trees tightly in place, but simply be there to keep them from getting blown over.

Straps should likewise not be tightly bound, but instead allow for a bit of motion with the breeze. Straps should cross over in a ‘figure eight’ pattern between trees and their stakes, so that trunks do not rub so abrasively against the stakes. Most trees need only two straps each, or two pairs of straps if two stakes are used, with support up high, and lower support to prevent outward bowing. If there are no branches to hold straps in place, straps must be nailed or otherwise attached to the stakes.

Some sturdy trees, like well developed redwood trees and small magnolias, may not need stakes. Palms and yucca certainly do not. However, limber trees like the various eucalyptus may need more support than just two straps. The problem is that many trees become dependent on their stakes and will not develop strong trunks if they do not need to.

It is better to prune maturing staked trees to limit weight and wind resistance (that might cause them to blow over) than to provide more support with heftier stakes. If a maturing young tree is relying on stakes and straps for support, it needs to be pruned. A young unstaked tree that begins to lean from the weight of its canopy should likewise be pruned until it regains its posture without getting staked and bound. Trees should never be tied to other trees, buildings or anything else that can be damaged by the tension.

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Cultivars Are Merely Cultivated Varieties

Cultivars are distinct within their species.

Nomenclature is simply the technique of naming. Botanically and horticulturally, it is also a precise method of classification. Large classifications divide into smaller and exclusive classifications, which likewise divide. Botanical families divide into many genera, which likewise divide into many species. Some species divide further into varieties or cultivars. 

For example, Schwedler maple is within the Sapindaceae family. This family divides into many genera including the maple genus of Acer. (Genera is plural of genus.) This genus divides into varied species, including the Norway maple species of platanoides. Norway maple divides into more cultivars, including ‘Schwedlerii’, which is the Schwedler maple. 

Therefore, the botanical name of the Schwedler maple is Acer platanoides ‘Schwedlerii’. Family names are omissible. Genus names justify capitalization. Species names do not. Both genus and species names appear in italics. (Incidentally, genera are more ‘genera’l than ‘speci’fic species.) Single quotation marks contain names of varieties and cultivars.

Varieties are, as their designation implies, variants of a species. Some are dwarf, like the dwarf pampas grass. Some bloom with atypical color, like the maroon Texas bluebonnet. Their variations are natural and at least somewhat inheritable. Cultivars are varieties that can not perpetuate naturally, so are reliant on cultivation. They are ‘cultiva’ted ‘var’ieties.

Some cultivars developed from breeding. Others are naturally occurring mutants that are desirable enough to perpetuate. Because their unique characteristics are not inheritable, perpetuation is artificial. Seed of cultivars that originated as mutants lacks any desirable mutation. Seed of extensively bred cultivars is genetically unstable, or may not be viable. 

Most cultivars therefore rely on cloning for perpetuation. Propagation by cutting, grafting, division, layering and tissue culture, generates genetically identical copies of an original. Although it is illegal to propagate patented cultivars for profit, most common cultivars are too old for patents. Many perennial cultivars, such as iris and canna, proliferate naturally. 

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Give Plants What They Want

Flowering crabapples are generally reliable for profuse bloom, but some varieties might perform and grow better where winters are cooler.

Dogwoods are certainly pretty as they bloom this time of year. They are rare, but seen often enough in nurseries to make one wonder why they are even more scarce in local gardens. Those that got sold in previous years should now be prominent features around town. The problem is that because they are not happy in local climates, dogwoods become dogwon’ts. They won’t bloom. They won’t provide good fall color. Many won’t even grow. Dogwoods prefer more humidity, so in local gardens, want to be sheltered from full sun exposure and drying wind by larger trees or buildings.

Nurseries generally stock plants that are appropriate for local climates. A few nurseries also have a few plants that would rather be somewhere else, but can be grown with certain accommodations. Reputable retail nurseries are generally careful to divulge which plants need more attention, and what their requirements are. However, many of the big garden centers in home improvement stores are more interested in selling what they can rather than selling what is actually appropriate, particularly since they thrive on turnover and replacing plants that do not survive.

Not all plants are as easy to grow as junipers and oleanders are. Japanese maples and rhododendrons like at least some degree of shelter from direct sun exposure and dry heat; but the California fan palm thrives in wicked heat. Plumerias and coleus can be damaged by even slight frost; but many apples and pears want more frost. Spruces like even moisture; but many yuccas rot without enough dry time.

This is why it is important to know how to accommodate plants that may be less than ideal for local climates. Those of us who choose to grow plants that have special needs should at least give them what they want if we expect them to perform as we want them to.

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Deadhead Spring Bulbs After Bloom

Most spring bulbs are done blooming.

Fruiting warm season vegetables that are now in season, such as squash, tomatoes and beans, are more abundant with regular harvest. Plants that produce such fruit respond to their natural obligation to generate seed. Deprivation of the fruit that contains their seed stimulates production of more. Similarly, it is helpful to deadhead some flowering plants.

Deadhead grooming is a type of pruning, even if it does not involve pruning shears. It is, in simple terms, the removal of deteriorating flowers after bloom. For some plants, it only improves aesthetic appeal. For many others, it redirects resources from seed production into subsequent bloom, or vegetative growth that eventually sustains subsequent bloom. 

Now that early spring bulbs are finishing bloom, it is time to deadhead them. Most bloom just once annually, so without the distraction of seed production, will prioritize vegetative growth into new bulbs to bloom for next year. Many of the summer bulbs that bloom later bloom more than once annually, so divert conserved resources into subsequent blooms.

However, many cultivars of spring bulbs are too extensively hybridized to produce viable seed. For them, deadhead grooming merely eliminates unappealingly deteriorated floral carcasses, while their foliage continues to sustain the development of new bulbs for next year. The foliage of most deteriorates slowly through warming spring or summer weather. 

Some extensively hybridized modern cultivars are not sterile though. Some can produce feral progeny that are less appealing than the hybrid parents, but are vigorous enough to displace them. Deadhead grooming eliminates most or all of the unwanted feral seed. Of course, for wild grape hyacinth and snowdrop, seed can be left to develop and disperse.

Established colonies of feral freesias can be allowed to make seed for more of the same. However, hybrid freesia benefits from deadhead grooming to eliminate feral seed. Dutch iris, narcissus, daffodil, tulip, hyacinth and lily can also benefit from deadhead grooming, for a variety of reasons. Some are sterile. Some are not. Some get shabby. Some do not.

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There Is Variety In Succulents

It is difficult to believe that this stout trunk outfitted with sharp spines is a euphorb, related to leafier poinsettias.

Cacti have thick, fleshy stems outfitted with nasty spines instead of leaves. Agaves and related aloes have stout, fibrous stems that are mostly obscured by thick, fleshy leaves. (Only a few somewhat rare aloes develop bare trunks and stems.) What they have in common is that they all are succulent plants, collectively known as succulents.

There are all sorts of other succulents. Humongous saguaro cactus have hefty trunks and limbs. Diminutive impatiens (like busy Lizzie) are grown as annuals for their colorful and very abundant flowers. Many succulents have succulent stems. Many have succulent leaves. Some, like the common jade plant, have both succulent leaves and stems. Trailing ice plants, leafy begonias, and sculptural euphorbs (related to poinsettias) are all succulents.

Many succulents store water in their succulent parts because they live in dry climates. Because moisture is such a commodity where they live, cacti protect their succulent stems with sharp spines. Agave protect their leaves with sharp teeth. Euphorbs are equipped with caustic sap, and many also have spines like cactus have. Fortunately, most succulents are not so unfriendly.

Almost all succulents are remarkably easy to propagate from cuttings or by division. In the wild, pieces of prickly pear cactus that fall onto the ground will begin to develop roots through the rainy weather of autumn and winter, and be ready to grow into new plants by spring. In the home garden, cactus cuttings should be left out for a week or more so that the cut ends will ‘cauterize’ (Actually, they just dry out a bit.) and be less susceptible to rot once they get plugged into the ground or pots to grow roots. Alternatively, clumping cactus that develop multiple main stems from the base can be divided, although the spines make handling them difficult.

Most aloes and some agaves produce basal shoots known as pups, that can be split from the main plants to grow into new separate plants. Agaves that do not produce pups while young typically start to produce pups after a few (or many) years, as they mature enough to bloom. Many of the larger types produce an abundance of pups after bloom, since the main shoot dies as flowers deteriorate. If desired, one or more of the pups can be left in place or planted back to replace the parent plant.

Most other succulents are even easier to propagate. Small cuttings can be plugged wherever new plants are desired. Some can even be grown from leaf cuttings!

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Moles Are Different From Gophers

Gophers are more destructive than moles.

Wildlife belongs in the wild. Many of us appreciate it there, and get pictures of it to share with others as if it is rare and unusual. Deer, raccoons, skunks, squirrels, gophers and so many other residents of the wild are not so appealing in home gardens. They all need to eat. None are tactful about it. Some eat foliage. Some eat fruits. Moles eat larval insects.

That seems like it would be beneficial to the garden. In some situations, it is. Not only do moles inhibit the proliferation of grubs that damage roots, but they also aerate dense soil. The problem is that they heave soil as they excavate just below the surface. This activity damages lawns and shallow ground cover. Uninhibited grubs might cause less damage. 

Gophers often take the blame for damage that moles cause. However, gophers are much more destructive. They excavate more substantially, and generate larger mounds. While moles consume mostly detrimental grubs, gophers devour roots and any other plant part within the soil. Gophers do not hesitate to kill the most important plants in the landscape. 

Like gophers and other rodents, moles can not take much time off for hibernation through winter. The weather is just too mild. Although they are less active during cool weather, or while there is less to hunt, they never stop excavating. They merely become more active now because, as the weather warms, they can plan for a family, and find plenty of grubs.

Mole excavation generates distinctive small ‘berms’ of displaced soil within lawns. Such berms extend randomly in no particular direction, but are impressively consistent in form. Mounds of expelled soil are small and sporadic, or may not be evident. Moles often push their way below the surface of firmly rooted turf, without expelling any soil to the surface.

Unfortunately, moles can be about as difficult to dissuade as gophers. The most practical means of repellent is to eliminate the grubs that they crave, which can be difficult without insecticide. Blood meal and bone meal are fertilizers that can supposedly repel moles by their objectionable aroma, but require frequent application. Traps also require diligence, as well as precision.

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Palms Need Proper Planning Too

Every species of palm has a distinct personality. All have attributes; but many also have the potential for considerable problems.

California has no more native palms than Oklahoma has with the diminutive dwarf palmetto. The stately California fan palm, which is also known as the desert fan palm, inhabits warm desert regions in southern California. It is what put the ‘Palm’ in ‘Palm Springs’. However, because it likes heat and minimal humidity, it is not so happy away from deserts. The very tall and lean Mexican fan palm is closely related to the comparably stout California fan palm, but is so happy in local climates that it naturalizes and can be invasive.

The queen palm has a leaner trunk, and a broader and more billowy canopy. It rarely self sows, but is so overly popular that it very often gets planted in bad situation where it does not have room to grow. Unlike fan palms that have rounded palmate leaves that radiate outward from the ends of bare petioles (leaf stalks), the queen palm is a ‘feather’ palm, with pinnately compound leaves comprised of narrow leaflets arranged along stiff midribs.

The massive Canary Island date palm is another feather palm, with a broad canopy and bulky trunk. Like Mexican fan palm, it often self sows, so gets into some weird situations. The foliage is so thick that is commonly becomes infested with rats and pigeons. Female trees produce messy fruit that keeps rats and pigeons well fed.

Whether they get planted intentionally or simply appear in the landscape, the main problem with all these and other large palms, is the expense of maintenance, since they can only be maintained by professional arborists who know how to climb such large branchless trees. Without regular grooming, fan palms that are so often allowed to retain long beards of old leaves become fire hazards, and have the potential to drop dangerously heavy sections of their beards without warning. Removal of old deteriorating leaves from the huge canopies of Canary Island date palms is quite an chore!

There are few small palms, like windmill palm and Mediterranean fan palm, that are more proportionate to compact gardens. Windmill palm has a strikingly shaggy trunk and a compact canopy that is easy to groom before it grows beyond reach. Mediterranean fan palm has multiple trunks that grow so slowly that it takes many decades for them to grow beyond reach. Nasty sharp thorns on their petioles make pruning difficult but not impossible.

Selection of a palm that is appropriate to a particular situation is just as important to limiting serious long term problems as the selection of any other tree is.