Autumn Simply Will Not Wait

40917thumbReady or not, it will be autumn in just a few days. Formal hedges can be shorn one last time if they need it. They will not grow much until spring. Actually, photinia and the various pittosporums should not be shorn much later than now if they exhibit any dieback. Some of the diseases that cause dieback are more likely to infest freshly cut stems during rainy weather. Citrus and plants that can be sensitive to frost should not be pruned later, since pruning can stimulate new growth that will be more sensitive.

For the same reason, most plants should not need fertilizer as their growth naturally slows. Through winter, new growth is likely to be damaged by wind or discolored by nutrient deficiency. Even if the nutrients that keep foliage green prior to autumn are in the soil, some are less soluble at cooler temperatures. It is really best to allow plants to get some rest. Only plants that are active through winter, like cool season vegetables, cool season annuals, and some cool season turf, will benefit from fertilizer.

However, some plants that are generally dormant through cool winter weather will not be completely inactive. Many plants, particularly tough evergreen perennials like lily-of-the-Nile, African iris and many ferns, continue to disperse their roots to be ready to sustain new foliar growth next spring. This is one of the reasons why autumn is the best time to get such plants into the garden, even if they do not seem to do much until spring. Autumn is also a good time to seed lawns or install sod.

The other reason for planting in autumn is that, as the weather gets cooler and rainy, new plants that have not yet dispersed their roots will be less likely to dry out than they would be in spring or summer. Some bulbs that will soon be available in nurseries want to be in the garden before winter because a bit of cold weather promotes healthier bloom.

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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.

Fall

P81013I prefer to call it ‘autumn’. It sounds prettier. Perhaps it even sounds a bit more exotic, like something that happens in far away climates were the seasons are more distinct, and the weather gets a bit cooler this time of year.
‘Fall’ sounds more like a simple verb. It is merely what outdated leaves do when deciduous trees no longer have use for them. Many trees in mild climates do not even bother to indulge their foliage with a bit of color first.
Exotic places like Pennsylvania, Minnesota and Kentucky get autumn. Oklahoma, Oregon and Alaska get it as well, although it is commonly mistaken for fall because the deciduous foliage of most native specie turns brown in Oklahoma, and yellow in Oregon and Alaska, with significantly less of the oranges, reds and other bright colors that are so prominent in other regions.
Rather than complain about the minimal variety of color among out native specie, and how the best color is provided by very accommodating exotic specie that color well even in our locally mild weather, I prefer to brag about how excellent the weather is through our fall. Except for the longer and cooler nights, our fall is like an extension of summer. It is often referred to as Indian summer. While others share pictures of their colorful autumn foliage, I get to share pictures of fall roses that continue blooming until frost,or even right through winter. Yes, in some regards, fall can be better than autumn.
Then, this happened. While dahlia, zinnia, black-eyed Susan and even rose continue to bloom for those whom I would otherwise shame with my superior blooms, fall moved in, and is already defoliating a few trees! Sweetgum is starting to turn orange and red, but cottonwood, box elder, various willows and other riparian trees are beginning to defoliate without much color at all. This black oak is significantly farther along. At least it turned a nice rusty brown before defoliating.
How embarrassing! I can brag neither about extended bloom through a late fall, nor the bright foliar color of autumn!P81013+

Winter Dormancy Begins In Autumn

50923thumbAutumn is for planting . . . but not much else. While it is important to get certain new plants into the garden before cool and rainy weather, other gardening chores will not be necessary while plants are becoming less active before winter dormancy. Raking falling leaves is probably the biggest of the new chores that are specific to autumn.

Formal hedges that have been getting shorn regularly since spring may not need to be shorn again until next spring. They simply will not grow much between now and then. If possible, pittosporum and photinia should not be shorn once the weather gets rainy. Their freshly cut stems are more susceptible to certain diseases while wet than during dry weather.

Citrus and tropical plants should not be pruned late because pruning stimulates fresh new growth that will be susceptible to frost later in winter. Even if tender new foliage does not get frozen, it can get discolored and disfigured by cold weather. Cool weather inhibits vascular activity necessary to sustain the development of healthy new foliage anyway.

For the same few reasons, fertilizer will not be necessary later in autumn. Fertilizer can potentially stimulate new growth when it is not necessarily wanted. Also, some nutrients in fertilizer are less soluble (or chemically unavailable) while the weather is cool. Only plants that grow through winter, like cool season annuals, vegetables and grasses, will want fertilizer.

Planting is done in autumn because plants are either dormant or less active than they had been during warmer weather. They can take their time to disperse their roots into comfortably cool and damp soil. Evergreen plants do not draw as much moisture from their roots while foliage is cool and damp. Deciduous plants draw even less moisture without foliage.

Spring blooming bulbs get planted in autumn not only so that they can disperse their roots leisurely, but also because they need to get chilled to bloom well. Bulbs can be phased, so that those planted earlier will bloom before those of the same kind planted later. However, if planted too late, they may not get sufficient chill.

Early Autumn Color Might Disappoint

60928thumbIt might seem like autumn color is a bit early this year. In the wild, where there is no irrigation, native box elders, and maybe some of the cottonwoods and sycamores, are already yellowing. The box elders are already dropping some of their foliage. However, this is not caused by an early chill. It is caused by late warmth after an otherwise mild summer, and might inhibit better color later.

It is still impossible to say for certain. There are so many variables that affect autumn color, such as temperature, humidity and daylength. Some of the plants that develop color late, like flowering pear trees in irrigated landscapes, might not be bothered too much by the same variables that are troubling wild box elders now. Where autumn weather is so mild, color is unpredictable anyway.

Sudden cool weather after mild weather late in summer would have been better for autumn color. (Warmth through the middle of summer is no problem.) Foliage lingers best if the weather stays cool without getting too cold. Wind and rain will eventually dislodge foliage. Sheltered sweetgums might hold their foliage until just before it gets replaced by new foliage late in the following winter.

The earliest trees to color, as well as those that are notoriously less reliable for color, are the most likely to be inhibited by the weather this year. Besides box elders, cottonwoods and sycamores, other marginally colorful trees like willows, walnuts, maples, elms, redbuds, smoke trees and deciduous oaks, may develop bland color. Mulberries and tulip trees, though early, are more reliable.

Sweetgums (which are also known as liquidambars) , flowering pears, Chinese pistaches and maidenhair trees (which are also known as gingkos) are the most reliable trees for color locally. Maidenhair trees turn remarkably bright yellow. The others can be various shades of bright yellow, orange, red or burgundy red, (although Chinese pistaches do not not often get burgundy color here). Crape myrtles have the potential for the same color range if conditions are right.

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.

‘Green’: The ‘Other’ Autumn Color

P71202After reading so much about the exquisite foliar color that most everyone else in the Northern Hemisphere gets this time of year, I must admit, I can get rather envious of those who experience four seasons instead of just two. The abundance of spring in the Southern Hemisphere does not help. Why have I not found a garden blog from Ecuador or Indonesia so that I have something to point and laugh at? It just isn’t fair.

Well, now I have something to brag about.

I found this bright red leaf on a crepe myrtle in town. Isn’t it pretty? Go ahead, you can tell me. It is gorgeous, RIGHT? Go on; say it! Say it NOW! LOUDER!

Soon, all the foliage behind it will be turning red and orange with maybe a bit of yellow. Can you see it? I think some of those leaves are starting to consider turning color right now! I just love this time of year!

There is other foliar color. I just happened to take a picture of this single leaf first. REALLY! There IS autumn color here.

In fact, most of of the foliar color here this time of year is a very different color from what is so common elsewhere. It is known as ‘green’. Have you ever heard of it? Yes, of course! It is that color that you saw so much of in spring and summer!

‘Green’ is such a splendid color! It looks particular exquisite on palm trees. Do you know what a palm tree is? Of course not. Well, we can talk about that later. For now, I will just post this spectacular picture of a rich ‘green’ sweetgum tree! Can you remember the last time you saw one in ‘green’? The fallen leaves on the ground remind us that this is autumn.P71202++

Autumn Color That Proves It

71122thumbThere may not be a good time to talk about it this year. The late warmth really put a damper on some of the autumn foliar color. Some trees are dropping their leaves as soon as they start to turn color, leaving only fading green leaves in their canopies. Only the most reliable trees for autumn color, sweetgum, Chinese pistache, flowering pear and gingko, are trying to make up for lost color.

Now, just because these four trees happen to color well and reliably in autumn does not necessarily mean that they are the right trees for every application. No tree is perfect. Gingko comes close in regard to adaptability to a broad range of applications, but provides only bright yellow autumn color. Flowering pear can be an excellent tree in most regards, but it very susceptible to fire blight.

The other two eventually get too big for some applications. Chinese pistache gets broad with low branches, and old trees (that predate the selection of the standardized male cultivar) can be messy with tiny but profuse fruits. Mature sweetgum trees are notoriously messy with obnoxiously spiked mace-like fruits, and can develop serious and potentially hazardous structural deficiency.

There are certainly more trees and plants that can provide foliar color in autumn. These just happen to be four of the most reliable, and most brilliantly colored. Chinese tallow turns dark burgundy and almost purplish, but colors best in response to a sharp and sudden chill. Red oak turns a monochromatic brown like that of a paper bag, but of course, the color does not appeal to everyone.

Years ago, it was advisable to select flowering crabapples and flowering cherries while blooming in spring because that was the most accurate representation of their floral color. (Photographs were not what pictures are nowadays.) This is still good advice. For autumn color, it is probably better to observe trees around the neighborhood, and then identify those that are most appealing.

Once a few are identified, it is easier to research them to learn about their distinct characteristics, and to determine if they are appropriate for particular applications or situations. Some might be too big. Some might be too messy. Some are not as colorful as others. Persimmon has the added bonus of fruit. Crape myrtle blooms nicely in summer. It is better to know before planting them.