Sweetgum

Sweetgum is impressively colorful for autumn.

This might be the most spectacular and most reliable of autumn foliage available locally. Sweetgum, Liquidambar styraciflua, begins to develop a brilliant blend of yellow, orange and red in response to the earliest mild chill of autumn. It defoliates slowly to retain much of its colorful foliage through the earliest rain and wind of winter, and perhaps even later.

Sweetgum leaves are palmate, and about four inches wide, with five pointed lobes. One very rare cultivar has hierarchically lobed leaves, with lobes on lobes. Another has blunt lobes. Some cultivars as well as individual trees favor particular foliar colors for autumn. ‘Burgundy’ exhibits more dark red color than typical, and retains foliage later than typical.

Mature trees can grow fifty feet tall, but are not very broad. They can get taller and lankier to compete with other tall trees. Their upright form conforms to grove arrangement within large landscapes and parks. Unfortunately, their aggressive roots can displace concrete. Their branches can be structurally deficient. Their spiky and hard fruit can be obnoxious.

Autumn Foliage In Mild Climates

Minor chill initiates autumn foliar color.

Colorful foliage is always present. After all, green is a color, even without any other color or variegation. Defoliation of deciduous foliage during autumn reveals evergreen foliage beyond, even if fading through winter. Immediately prior to defoliation though, deciduous foliage of quite a few species temporarily becomes spectacularly colorful autumn foliage.

Whether deciduous or evergreen, foliage that is most colorful during spring and summer contains chlorophyll. Regardless of how variegated, reddish, purplish, yellowish or other color it might be, it is also green to some degree. It could not be photosynthetically active otherwise. Colorful autumn foliage exhibits brighter color as its chlorophyll decomposes.

Autumn foliage is most spectacular where it is native, such as New England. Much more of it inhabits forests than home gardens. It is not spectacular within forests here because only a few sparsely dispersed native species produce impressive foliar color for autumn. Its naturally local scarcity likely contributes to its limited popularity within home gardens.

Locally mild weather also limits the popularity as well as the potential of autumn foliage. Many of the most colorful maples of New England merely turn blandly pallid yellow prior to hastily premature defoliation here. However, several other species develop exemplary foliar color in response to minor chill, and seem to be as happy here as in New England.

Chinese pistache, sweetgum, flowering pear and ginkgo are four trees that most reliably provide autumn foliage here. Crape myrtle is a smaller tree that is almost as reliable, and blooms splendidly for summer. Persimmon gets as colorful as Chinese pistache, with an abundance of fruit. Boston ivy is a vine with color that is comparable to that of sweetgum.

Of course, even the most appealing of plants are not perfect. Their innate characteristics are relevant to selection. For examples, trees occupy significant space. Ginkgo becomes bright yellow, but without any other color. Sweetgum produces obnoxiously prickly fruits. Flowering pear is susceptible to fireblight. Boston ivy clings to surfaces and ruins siding, paint and fences.

Sweetgum

Sweetgum colors with minimal chill.

The excellent and remarkably brilliant shades of yellow, orange, red and burgundy of the foliage in autumn suggest that sweetgum, Liquidambar styraciflua, is from New England. However, it is native between New Jersey, Florida and the eastern edge of Texas, as well as isolated forests of Central America. It actually prefers mild climates to where winters are too cold. Mature trees are generally columnar (relatively narrow) and less than fifty feet tall where well exposed, but can get more than twice as tall to compete in forests.

Unfortunately, mature sweetgum trees can be somewhat problematic in urban gardens. Limbs are often weak enough to break in wind, or if they get too heavy from the weight of their own foliage. Also, the abundant round seed pods are outfitted with nasty spikes, like little maces almost two inches wide. They are painful to step on, and can actually be quite hazardous.

Autumn Foliar Color Begins In October

After blooming so colorfully for summer, crape myrtle foliage turns bright orange and red for autumn.

Why do so many from other regions comment on the mild climates of the west coast of California as if pleasant weather is a deficiency? If horrid summer heat and frigid winter cold were worth bragging about, not so many people would have been so eager to migrate here.

Contrary to popular belief, the four seasons, although considerably milder than in other regions, are enough to keep our gardens productive, dynamic and even colorful in all seasons. All sorts of deciduous plants and fruit trees get just enough chill in winter to bloom reliably in spring. The warming weather between winter and summer that gets most plants to bloom is what spring is all about. Summer is then warm enough for fruit and vegetables to develop. Then there is autumn, when so many deciduous plants turn flashy colors before winter dormancy.

Although the mild weather limits the choices, there are still a few plants to provide autumn foliar color. Actually, autumn is not so colorful locally primarily because the potential for color is not exploited like it is elsewhere. There are just so many other plants that do not turn color in autumn to choose from. Really, Vermont would be less colorful if palm trees grew there!

Sweetgum, Chinese pistache, flowering pear and maidenhair tree are the most reliable trees for autumn color. Maidenhair tree turns remarkably bright yellow. The others get the whole range from yellow to orange to red. Sweetgum also gets burgundy, and has the added advantage of holding foliage until it gets knocked off by wind or rain. Where the big, bright orange (and yummy) fruit that hangs through winter is desirable, Japanese persimmon is as colorful as Chinese pistache. (Persimmons are horribly messy if not harvested.) Various poplars, tulip tree and black walnut can almost get as bright yellow as maidenhair tree.

Crape myrtle and redbud are shrubby plants that provide good autumn color. Redbud turns clear yellow. Crape myrtle though, can also get bright orange and brownish red. Several of the Japanese maples, although not always as reliable, can actually get even more colorful if the weather is right. Boston ivy (which is actually related to grape) is the most colorful of climbing vines, but because it attaches directly to whatever it climbs, it is best on concrete walls that it will not damage.

Snowball Bush

Even without the variety of color of hydrangea, these relatively delicate, crisp white flowers of snowball bush are quite elegant.

Like small, clear white hydrangea blooms, the round, three inch wide floral trusses of snowball bush,Viburnum opulus ‘Roseum’, are composed of many smaller flowers. Unlike hydrangeas that bloom after vegetative (stem and foliar) growth, snowball bush blooms early, so that as it finishes, deteriorating blooms will be obscured by soft green foliage before anyone notices. The distinctively lobed, three inch wide leaves get quite colorful in autumn. Snowball bush should not be shorn, but can instead be pruned aggressively while bare in winter. Older or obtrusively tall stems should be pruned to the ground where possible. Good sun exposure without too much reflected glare or heat promotes bloom and autumn foliar color. Mature plants can get ten feet tall and nearly as broad.

Six on Saturday: New England?

New England is even farther away than Williamsburg. Although I have never been there, I sometimes think that some of the vegetation here resembles vegetation there, particularly as foliage and berries get colorful during autumn and winter. Autumn is a bit later here, and does not last as long. The associated color is relatively subdued. There are not as many colorfully deciduous trees. I do enjoy showing off what we get though. There is so much more to California than boringly evergreen palm trees and redwoods; and redwoods happen to make an excellent backdrop for New England style fall color! I will brag about various palms later.

1. Rio Grande turkey was intentionally naturalized here a long time ago, but only began to invade local home gardens since about the 1990s. To me, they look like they belong in New England.

2. Lantana camara makes these weird black berries, which the turkeys are not interested in. Just like turkeys, colorful (or just black) berries in autumn remind me of gardens in New England.

3. Moss, which had been rather grungy and brown through late summer, is now rich and vibrant green from rain last Wednesday. I suspect that moss such as this is common in New England.

4. Tulip tree, Liriodendron tulipifera, is native to neither Maine nor New Hampshire, and was extirpated from its two native counties in Vermont, but is native to other parts of New England.

5. Flowering dogwood, Cornus florida, is coincidentally extirpated from the same two counties in Vermont that tulip tree formerly inhabited, and is also native to other parts of New England.

6. English holly, Ilex aquifolium, is from England, which is the original or Old England. It is naturalized here. Just like the other five of these six, to me, it looks like it belongs in New England.

This is the link for Six on Saturday, for anyone else who would like to participate:

Maidenhair Tree

Maidenhair tree leaves look rather ‘fishy’.

There are not many trees that are as reliable for strikingly bright and clear yellow autumn foliar color as the maidenhair tree, Gingko biloba, is, even in mild coastal climates. The distinctive leaves flare out like fish tails, each with a prominent cleft that divides it into two wide lobes. (The species name ‘biloba’ means ‘two lobed’.) Some cultivars lack foliar clefts, have narrower leaves, or even develop milder yellow color in autumn. Those developed for home gardens exhibit relatively symmetrical branch structure, and are exclusively male, so can not produce the stinky fruit that some older female trees drop. (Trees grown from seed can be either male or female. Female cultivars are grown for fruit production and bonsai.) Some ancient trees in Japan, Korea and China are more than a hundred feet tall. Fortunately, maidenhair tree grows slowly enough to stay proportionate to compact urban gardens for many decades.

Maidenhair trees develop the best yellow fall color.

Gardens Show Their True Colors

California gets autumn foliar color too.

Contrary to popular belief, good autumn foliar color, or ‘fall color’, is possible on the West Coast. Mild weather only limits the options for trees, shrubs, vines and perennials that color well. Besides, autumn foliar color simply is not a popular priority in western gardening.

Boston ivy must be the best climbing vine for color in autumn. Unfortunately, it is too aggressive for refined urban gardens, and clings with ‘holdfast discs’ that damage the surfaces that it climbs. It is better for freeway soundwalls and interchanges. Grapevine is a more docile option, and also produces grapes, but most cultivars (cultivated varieties) are not too remarkably colorful. Wisteria can turn an appealing shade of soft yellow where well exposed, but its best asset is still the colorful and fragrant bloom in spring.

Eastern redbud, crape myrtle, smoke tree and currant are some of the better shrubbery for autumn foliar color. Of these, Eastern redbud develops the most subdued shade of yellow; and crape myrtle develops the most brilliant shades of yellow, orange and red. Both are incidentally considered to be small trees. Smoke trees that have purplish foliage in summer are typically less colorful in autumn than those with green summer foliage. Some of the Japanese maple trees that display good color in autumn are smaller than some of the larger shrubbery.

The North American and European maples that are so colorful where autumn weather is cooler are not so impressive here. Even if the color is good, the foliage does not linger very long, but instead falls as soon as the weather gets breezy or rainy. Silver maple and box elder (which is actually a maple) which are so pretty and green through summer can actually look rather dingy as they yellow for autumn. Fruitless mulberry, tulip tree, black walnut and the various poplars and locusts can color well if the weather is just so, but display only bright yellow without orange or red. Maidenhair tree impresses with the same limited color range only because it is so reliable, and the yellow color is so very brilliant.

Really, the best trees for autumn foliar color are still sweetgum, Chinese pistache and flowering pear. They do not need much cool weather to display impressively brilliant blends of yellow, orange and red. Where the messy fruiting structures (maces) and aggressive roots are not likely to be a problem, sweetgum is a tall and elegant shade tree. Sweetgum trees innately hold their colorful foliage well, and some sheltered trees sometimes hold their foliage through most of winter. Chinese pistache is neither as messy nor as aggressive as sweetgum is, as it forms a broad and low canopy that is likely to need pruning for adequate clearance. It is becoming more popular as a street tree in many municipalities. Flowering pear is perhaps the most cooperative of the three if pruned to improve structural integrity while young, but stays smaller than the others. It is actually quite proportionate to smaller gardens of modern homes.

Chinese Pistache

Chinese pistache colors with minimal chill.

Those who crave fall color in mild climates should appreciate Chinese pistache, Pistacia chinensis. It is happy to provide fiery yellow, orange and red color in response to a slight chill. Actually, it retains its colorful foliage later into the season with mild chill than it does with frosty weather. Rain eventually dislodges all of its deciduous foliage through winter.

Because it is so resilient to harsh situations, Chinese pistache is popular as a street tree. Pruning is necessary to establish adequate clearance of broad limbs over roadways and sidewalks. Since roots can be shallow with regular watering, root barriers should protect nearby pavement. However, established trees do not need regular watering, if any at all.

Old Chinese pistache trees, as well as those that grow wild from seed, are either male or female. Female trees produce tiny but annoyingly abundant fruit. Modern cultivars are all male, and therefore fruitless. They may get more than forty feet tall, with broad canopies. The pinnately compound leaves are just about eight inches long.

Fall Color To Fall For

Fall color develops with seasonal changes.

Autumn is also fall here. Actually, ‘fall’ is the more popular name. It had been the popular name in England during the Sixteenth Century. The (generally) French name of ‘autumn’ became more common there during the Seventeenth Century. Yet, both names remained in use in the American Colonies. That is why autumn foliar color is more simply fall color. 

The natural fall color in New England, the Appalachian Mountains, the Rocky Mountains and the Great North Woods is famously exquisite. So many of the native deciduous trees develop remarkable fall color in response to local weather conditions. These same trees might not get sufficient chill to develop comparable fall color in milder climates of Florida. 

In most regions of California, natural fall color is limited by the ability of native species to develop such color. Bigleaf maple and the various poplars turn bright yellow with a slight chill, but are not abundant. Even when chilled, the foliage of most other native deciduous trees simply shrivels and falls without much color. Most of the native trees are evergreen. 

Therefore, most of the best local fall color is provided by exotic (nonnative) tree species. Such trees not only develop remarkable fall color, but do so in response to minimal chill. Sweetgum, flowering pear, Chinese pistache and ginkgo are four trees that most reliably develop brilliant fall color where winter weather is mild. None are native. All are popular.

Ginkgo turns brilliant yellow. The other three display various colors that range from bright yellow, to fiery orange, to rich red and burgundy. Their colorful foliage lingers longer than that of other deciduous trees. Sweetgum and flowering pear might retain fall color until it succumbs to rain in winter. Of course, these are not the only options for reliable fall color. 

No tree is perfect. Although very colorful in autumn, sweetgum is notoriously structurally deficient, and produces obnoxiously spiked fruiting structures. Flowering pear is innately susceptible to fire blight. All deciduous trees drop leaves, which need raking. Trees must conform to their situational limitations, as well as their particular landscape applications.