Why Autumn Is Also Fall

50923thumbNow that leaves are falling, they need to be raked. Large leaves, like those of sycamore and fruitless mulberry, can shade out lawn, shallow ground cover or dense shrubbery. If shade is not a problem right away, mildew can be after only a bit of rain. If abundant enough, finely textured silk tree or jacaranda foliage that typically sifts harmlessly through shrubbery and most ground cover, can accumulate and damage lawn, dichondra and the densest of ground cover. Walnut foliage has an herbicidal effect on sensitive annuals and some perennials.

Foliage is only beginning to fall. Cooling weather causes deciduous trees to shed more. Rain and wind bring the foliage down even faster. Even evergreen trees that naturally shed throughout the year will likely shed more through the upcoming wintry weather. Some trees start to defoliate early in autumn. Some hold their foliage until frost. Some trees that seem to be evergreen hold their foliage through winter, and then only drop their older foliage as it gets replaced by new foliage as winter ends.

Pavement and decks should be raked of leaves, not only to avoid staining, but also because rotting leaves can become dangerously slippery. Curbside gutters are too visible to get neglected for too long. However, heavy rain can quickly deliver to the cleanest of gutters a mess of fallen leaves as well as any other debris and litter that happens to be up the road. Strong wind can be filtered through hedges, leaving drifts of blowing leaves.

Leaves should also be cleared from roof gutters and downspouts, and may need to be cleared away again later in the season. More debris may need to be removed from awkward spots where it might accumulate, such as behind chimneys. Flat roofs may need to be raked.

There are a few exceptions to the need to rake fallen leaves. Where they get absorbed into coarse ground cover like Algerian ivy, falling leaves are generally not a problem. Pine needles and cypress foliage can be left if it happens to be useful for the natural suppression of weeds. Mature coast live oaks and valley oaks that are accustomed to a layer of their own fallen leaves over the surface of the soil actually want it to stay. For them, the foliar debris is a mulch that adds organic matter, insulates the soil, and retains moisture.

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Colorful Foliage Needs No Bloom

90227thumbThere is no shortage of color for the garden here in our mild climates. If we want to, we can grow various flowers to bloom at various times throughout the year. If that is not enough, we can grow plenty of colorful foliage too. Evergreen sorts can stay fresh and resilient to minor frost all winter. A few deciduous plants and warm season perennials with colorful foliage will refoliate in spring.

Besides the various shades and hues of green, foliage can be variegated with white, cream, gray, chartreuse, yellow, gold, red or pink. Such variegation can be stripes, blotches, spots, margins or lacy patterns. New spring growth of some variegated plants is blushed with pink or red. Plants with blue, gray, silvery, bronze or purplish foliage are mostly monochromatic, without variegation.

Just as most popular flowers became less efficient at their primary function of attracting pollinators, as they were bred and developed to be bigger and more colorful than they naturally were, most colorful foliage is not an an advantage to the plants that produce it. After all, foliage needs chlorophyl for photosynthesis. Variegated portions of leaves lack chlorophyl, so are much less efficient.

In fact, many variegated plants originated as mutant growths, known as ‘sports’, that appeared on unvariegated plants, and were cloned. Many try to revert back to green by producing their own unvariegated sports. These green sports grow faster with more chlorophyl, so can overwhelm variegated growth if not pruned out. Monochromatic blue or gray foliage is not mutant growth, but is instead a natural adaptation to extreme exposures, mostly at high elevations, so is not prone to reversion.

English holly, English ivy, euonymous, silverberry, New Zealand flax, mirror plant and various pittosporums are some of the more popular variegated plants. Purple leaf plum, purple smokebush and a few cultivars of Japanese maple are popular plants with purplish or bronze foliage. Blue spruce, American agave, Arizona cypress and various junipers have exquisite bluish or gray foliage.

Fall Color Is More Foliar

71122As zinnias, petunias, cosmos and other warm season annuals fade in the cooling weather, we might add a few chrysanthemums or marigolds for color through autumn, or we might go straight for pansies, violas or other cool season annuals that will provide color through winter. In the locally mild climate, there is always potential for some sort of colorful bloom. Mild weather has advantages.

It also has a few disadvantages. It is what limits the variety of apples that can be grown here. It limits the potential for bulbs that will naturalize. It is why we do not even bother with maple sugaring. Although mild autumn weather promotes colorful bloom of cool season annuals, and allows some of the warm season annuals to bloom right into winter, It subdues the color of deciduous foliage.

Sweetgum, Chinese pistache, flowering pear and ginkgo are the most reliable trees for autumn foliar color here, even in the mildest of autumns. Sweetgum and Chinese pistache exhibit the most impressive range of vibrant colors. Flowering pear can be comparable, and often displays deep burgundy red as well. Ginkgo exhibits only bright yellow, but it is probably the best of bright yellow.

There are a few more choices. Fruitless mulberry, tulip tree, black walnut and the poplars turn nice yellow if the weather is right, but they do not get quite as bright as ginkgo. If it gets cold enough, Chinese tallow turns rich purplish burgundy. Red oak turns a nice uniform brown. Most cultivars of crape myrtle can get as colorful as sweetgum, and also provide colorful bloom through summer.

Of course, it is very important to learn about the distinct personality of a particular tree before adding it to the garden. After all, no tree is perfect. Sweetgum eventually drops messy and prickly seed pods. Roots of both sweetgum and Chinese pistache can be aggressive with concrete. Flowering pear is susceptible to fire blight. Then there are a few trees that are colorful in autumn, that also have other benefits. Persimmon trees that are grown for their fruit turn the most fiery orange in autumn!

Fall For Colors Of Fall

51111thumbMild winter weather on the West Coast limits the choices for autumn color. So many of the trees, shrubs, vines and perennials that get so colorful where autumn weather is cooler do not get so colorful here. Mild weather also allows so many more evergreen plants and plants that do not get colorful in autumn to thrive here than in harsher climates. Consequently, the tougher and more colorful plants are not so common.

Fortunately for those who appreciate autumn color, there are a few choices that do not mind mild weather. The three most reliable trees for autumn color are sweetgum (liquidambar), Chinese pistache and flowering pear. All three turn yellow, orange and red. Maidenhair tree (gingko) is just as reliable, and turns bright yellow, but lacks orange and red. (‘Saratoga’ gingko turns pale yellow.)

If the weather is right, fruitless mulberry, tulip tree, black walnut and the various poplars display clear yellow foliage. Eastern redbud can do the same, but is a small tree. Smoke tree and crape myrtle are large shrubbery or small trees that can get as colorful with yellow, orange and red as Chinese pistache does. Japanese maples have the potential to turn yellow or even orange, but more often turn dingy brown.

Grapevines and wisteria are vines that can be somewhat colorful if they hold their foliage long enough to get noticed. Boston ivy, which is actually more closely related to grapevines than to ivy, is the most colorful of the vines in autumn. Unfortunately, it can be too destructive to paint, wood and whatever else it grabs hold of to be practical for home gardens. It works nicely on indestructible concrete walls.

Heavenly bamboo, which seems to have appealing but distinct foliar color for every season, turns richer shades of reddish bronze through autumn. Some cultivars turn rich brown. Others become more purplish red or burgundy. Unlike other autumn foliage that sooner or later falls through winter, heavenly bamboo is evergreen, so hold its color until it get replaced by another color in spring. Unfortunately, there are not many other evergreens that turn color in such mild weather.

Falling Leaves Get Into Everything

51028thumbEven if they had been clean since they were emptied out last winter, gutters (eaves-troughs) near deciduous trees will eventually need to be cleaned again as they collect falling leaves through autumn. Leaves may continue to fall for several weeks, and will fall more abundantly as they get dislodged by rain.

Too many fallen leaves clog gutters and downspouts. If too much debris is left in downspouts for too long, it rots and settles so that it can be very difficult to dislodge. If rainwater can not adequately drain through gutters and downspouts, it can only flow over the edges of gutters. The falling water can erode the ground below, and splatter mud onto nearby walls.

This may not seem like much of a problem, but the reason that gutters and downspouts drain rainwater to the ground gently is to keep the walls dry and clean. Damp walls are likely to rot, especially if water splatters into basement vents. This is why early American homes that lacked expensive gutters were often outfitted with dense ‘foundation’ shrubbery or perennials to soften the splatter.

Leaves that accumulate in the valleys of the roof (where perpendicular slopes meet) should also be removed. Debris can also collect on the upslope side of a chimney. Homes with room additions have more awkward spots to collect debris than unaltered homes. Flat roofs and parapet roofs are of course very likely to collect debris under trees, and may need to be raked more than once.

Vines should not be allowed to climb onto roofs. They can tear apart roofing material, collect debris, and promote rot. Likewise, limbs of trees and large shrubbery should not be allowed to touch roofs, gutters, or even walls. Their motion in the breeze is abrasive to shingles, gutters, paint and siding. They can literally grind off shingles and break terracotta tiles.

Tree limbs should also be kept clear of chimneys. Even during rainy weather, hot exhaust from a chimney can dry and ignite limbs that get too close. Pine, cypress, cedar, and palms with beards (accumulated dead fronds) are very combustible.

Leaves Are Starting To Fall

81003thumbAutumn is slow in getting here. Yes, as of last Sunday, it is now autumn. The date is determined by the equinox, so is the same for everyone in the Northern Hemisphere, and is the same for the arrival of spring in the Southern Hemisphere. It just takes a bit longer for autumn weather to develop in the mild climate here. Nights are cooler. Shorter days are not as warm as they had been.

Even without the pretty foliar color that cooling weather prompts in other regions, deciduous foliage is already beginning to fall. Poplars, willows and some other trees that a naturally endemic to riparian environments are the first to start. Some are actually developing a slight bit of color, mostly soft yellow. More colorful foliage needs cooler weather, so will develop as weather gets cooler.

Sooner or later, falling leaves will need to be raked from lawns and groundcover. Trees that drop their leaves for a long time through autumn and into winter necessitate more frequent raking, even if their leaves do not accumulate enough to do much damage. Trees that drop their leaves within a shorter season can quickly drop enough to shade out turf or groundcover, or cause them to rot.

Because fallen leaves can stain hardscape surfaces, they should be raked efficiently from pavement and decking as well. Those of us who do not mind the staining, or even appreciate its rustic patina, might leave some of the fallen foliage out for a while, but should not leave it out long enough to promote rot in decking. Some leaves cause staining quite quickly, especially if wet from rain.

If leaves need to be raked from the garden and pavement, they probably need to be cleaned from roof gutters and anywhere else they accumulate on roofs. Just like raking, the clearing of fallen leaves from gutters and roofs is scheduled around the timing of the falling leaves, although it is not nearly as frequent. It may even be unnecessary if trees are too far from roofs for their leaves to fall or be blown onto them. Leaves that stay in gutters too long eventually decompose and clog downspouts.

Leaves Are Starting To Fall

50923thumbAutumn color is different every year. Sometimes, early and sudden cool weather after a mild summer promotes good foliar color that lingers longer while relaxed trees slowly realize that they should probably start to defoliate. Sometimes, early wind and rain accelerate defoliation of otherwise good color. There are a few variables that trees must adapt their performance to.

Warm and arid weather two weeks ago started the process of defoliation suddenly and a maybe slightly early this year. Even before the weather gets cool, deciduous trees are already starting to shed the oldest of their foliage that they do not need in order to hold their youngest foliage a bit later into autumn. Evergreen trees do the same to limit desiccation.

Slightly breezy weather that was so pleasant after such heat was just enough to start dislodging deteriorating foliage. Now, leaves are already starting to fall before they develop much color. Redwoods and pines are likewise dropping browned needles. Fortunately, trees that are the most colorful in autumn tend to hold their foliage better until the weather gets cooler.

It is impossible to predict how colorful trees will be this autumn; although if storms are as healthy as predicted, the mild temperatures may inhibit color, while wind and rain dislodge colorful foliage. Regardless, it is already time to start raking falling leaves and needles. They can get messy, and when the rain starts, they can stain pavement and clog gutters.

When more foliage falls later in autumn, it will need to be raked from ground cover, surviving portions of lawn, and any other plants that collect it, so that it does not shade out the sunlight.

Herbs Are For All Seasons

70823thumbThere are only four seasons in which to grow herbs, but herbs are used for all sorts of seasonings. Most herbs are aromatic evergreen foliage. Some might be flowers, flower buds, stems, bark, seeds, roots or really any plant part. Those with the strongest flavors might be classified as spices. Herbs are used for culinary purposes. Many might be used medicinally. Some just smell pretty.

Most herbs are best fresh, like mint, chive, cilantro and parsley. Bay leaf and lavender are herbs that are more commonly used dried rather than fresh. Sage, rosemary and oregano can be used either dried or fresh, depending on the desired effect. Yet, for many of us, dried herbs are used merely because of convenience. They are available when their fresh versions are out of season.

Many gardening texts suggest that herbs that need to be dried should be collected and dried about now. That is true in the sense that most happen to be ready about now. Some might have been better earlier in the year. A few might need to mature a bit more. There are probably many that get collected and dried when it is convenient for us, or when overgrown plants need to be pruned.

Vegetative rosemary stems should be collected before they bloom again. Obviously, that might not be right now. It blooms in random phases. The trick is to catch it between phases. Lavender flowers get collected as they finish bloom. Oregano is an odd one, since the vertical stems with flower buds on top get cut for drying while the sprawling growth on the ground is good for fresh use.

Because rosemary is available throughout the year, it is not often dried. Even while in full bloom, there is plenty of foliage to go around. When it gets dried, it is probably because the dried flavor is preferred for a specific recipe. Other herbs are likely to be dried because they are not available during part of the year. Many herbs are annuals or perennials that die back through the winter. Drying the last bits of cilantro may not seem like a good idea now, but might be useful in winter.

Pinnate Leaves

P80428K.JPGThat refers to the pattern of the veins in the leaves. Long before studying horticulture and botany at Cal Poly, my classmates and I learned a bit about horticulture within the contexts of studying ‘nature’. While in the sixth grade, we all went to camp for a week. One of the many projects we did during that time was collecting a few leaves to represent three different vein patterns, and mounting them under clear plastic on a cardboard plaque. The three different patters were, ‘pinnate’, ‘palmate’, and ‘parallel’. I do not remember if we all used the same leaves, but for my plaque, I got a blue gum eucalyptus leaf to represent pinnate veins. Palmate veins were represented by English ivy. Parallel veins were represented by English plantain.

These two blue gum trees are the same trees that provided the leaf with pinnate veins for my plaque. This is not a good picture. There really are two trees here. The picture below is even worse, but shows that there really are two separate trees. They probably flanked a driveway to the old house outside of the picture to the right. They are not very healthy right now, and do not seem to be much bigger than they were back in November of 1978, when my sixth grade class was here at camp with them.

This camp happens to be right down the road from the farm. We are neighbors. It is gratifying to see that so much of the camp is just as it was four decades ago. The English ivy that was so common back than is completely gone now, probably because it is so invasive. The lawn around the blue gum eucalyptus used to be much weedier, and provided the English plantain leaves for my plaque.P80428K+

Vasona

P80114Only a few bits and pieces of natural native vegetation can be found on the floor of the Santa Clara Valley. They are primarily in spots that were not useful for some sort of development. Almost all of the big coast live oaks and valley oaks that lived in the flat areas are gone. Riparian vegetation still survives on the banks of creeks, and in adjacent areas where it has not yet been cleared.

Vasona Lake Park is a Santa Clara County Park situated around the small Vasona Reservoir just north of town. Although much of the natural vegetation was cleared a very long time ago, and exotic vegetation was either added or naturalized, several big native trees remain, including several California sycamore trees.

Because these grand sycamores were more common here than anywhere else in our childhood world, and we did not know what they were, my younger brother knew them simply as ‘Vasona’ trees. They were tall and gnarly, with big holes in their bulky leaning trunks. The lowest branches were far too high for us to reach, so we cold not climb them. The leaves were not clean and smooth like maple leaves, so we did not mess with them too much.

Unlike most deciduous trees that drop their leaves within a limited time in autumn, California sycamores drop their leaves whenever they want to. Most leaves fall in autumn. Some linger into winter. If the summer is exceptionally dry or warm, many leaves fall very early. Anthracnose can make the first spring leaves fall almost as quickly as they develop.

Somewhere along the line, my younger brother learned that catching a falling leaf before it reaches the ground is lucky. Consequently, we often ran after leaves that we saw falling from high up in the sycamore treees, if they were falling slowly enough for us to get to where they were going before they did.

I ignore them now. I notice the patterns of defoliation just because I am an arborist, but that is about the extent of it. However, I happened to see this leaf falling slowly from near the top of a massive California sycamore, and just had to catch it; my lucky Vasona tree leaf.