Watering Trees Is Still Important

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Trees in lawns, even drought tolerant sorts, expect to be watered somewhat.

All the optimistic predictions of a rainy winter do not help with the drought yet. Nice warm weather only makes the garden even drier. Many of us have let our lawns dry out, maybe with plans to replace them later. Some have decided to replace lawn with artificial turf, hardscape or other landscape features.

The problem with this is that trees and other large plants that have dispersed their roots under the lawns are thirsty for the volumes of water that they had gotten while the lawns were well watered. They can survive longer than lawn does without watering, and will adapt to less water when they do get it, but they can not do without water completely.

It seems silly to water artificial turf or new decking, but it is sometimes necessary, especially for thirsty trees like willow, ash, elm and redwood. This is why some artificial lawns are outfitted with the original irrigation systems of the lawns that they replaced.

Drought tolerant trees, like certain oaks and most eucalypti, are more adaptable. Of course, those that were originally watered generously are greedier. Those that got only minimal watering may not notice if they get none at all. Regardless of their requirements, they all can be watered less frequently than lawns were, but should be watered generously when they do get watered.

Generous, but infrequent watering soaks into the ground better to satisfy deep roots. It is actually what most trees prefer. Lawn needs frequent watering only because the roots are so shallow. Generous, but infrequent watering uses less water not only because less evaporates from the surface of the soil, but also because less water gets used.

For example, watering weekly for 20 minutes is a generous volume of water, but is still less than watering for 15 minutes three times each week. It is only 20 minutes of watering compared to forty five minutes of watering.

Camphor Tree

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Camphor trees have stout branch structure.

The best camphor trees, Cinnamomum camphora, are in parks and other spacious landscapes. Such trees have sufficient room for their broad canopies. Although they do not grow rapidly, they eventually get quite large, and perhaps too massive for confined urban gardens. Some of the older local trees are nearly fifty feet tall, and nearly as broad. They have potential to get much bigger.

Camphor trees excel as shade trees. Their light green or perhaps yellowish evergreen foliage is quite dense. Shade of groups of trees or large trees with low canopies inhibits the growth of lawn grass. Also, roots are likely to eventually elevate lawn or other features that are close to the trunks. Foliar canopies are billowy, but can be lopsided, especially in windy or partly shaded situations.

Trunks and main limbs of camphor trees are rather stout, and can be rather sculptural. Trees should be pruned for clearance while young. Otherwise, obtrusively low limbs can become prominent components of the canopies. The tan bark is distinctively checkered. It darkens handsomely with rain. All parts of camphor tree are quite aromatic. Frass from spring bloom can be slightly messy.

Shade Trees Adapt To Urbanism

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Traditional shade trees get quite large.

Modern urban home gardens are shadier and more confined than older suburban home gardens originally were. Modern homes are both taller and closer together on smaller parcels. Fences are also taller to compensate for the minimal proximity of adjacent homes. Less sunlight reaches the ground. There is not as much space available for shade trees. Nor is there as much use for them.

Huddled modern homes are simply not as exposed to sunlight as older suburban homes were. Sunlight is more of an asset than a liability. Walls, ceilings and windows are so thoroughly insulated that shade is less important. Solar arrays up on roofs must remain exposed to sunlight. Smaller and denser trees are more important for obscuring views of adjacent homes, rather than for shade.

Shade trees are still useful for rural and suburban homes. Shade helps to keep older and less energy efficient homes cooler through warmer summer weather. If strategically situated to the south, west or southwest, they shade homes during the warmest time of day. Well proportioned trees do not darken too much of their gardens. Deciduous trees allow warming sunlight in through winter.

The popularity of modern urban homes is directly proportionate to the popularity of small evergreen trees. Such trees fit into smaller garden spaces, and permanently obscure unwanted scenery. Big deciduous shade trees that are practical for larger garden spaces become obtrusive in confined spaces. Defoliation in winter reveals unwanted views, and deprives the landscape of privacy.

Some of the more practical of small evergreen trees are actually large shrubbery. English laurel, Carolina cherry, photinia, hopseed bush and various pittosporums can get high enough to obscure neighboring windows. All are conducive to pruning if they get too tall. If staked on single straight trunks, or pruned to expose a few sculptural trunks, they do not occupy much space at ground level.

Tristania laurina, and some melaleucas are naturally small to midsized evergreen shade trees. Some species of Podocarpus can be pruned as midsized trees.

Six on Saturday: Suburbia II

As I said last week, the Santa Clara Valley is the best place in the entire Universe for horticulture. That is where these pictures came from. Although I planted only the Ilex aquifolium of the second picture, I collected all six of these plants from various sources over the years. They have been quite happy here. I will now be taking more copies or originals of all but Ilex aquifolium.

1. Juniperus virginiana – is my favorite this week. I know it is uninteresting to those who are familiar with it, but it happens to be one of only a few that I brought from Newalla in Oklahoma.P00808-1

2. Ilex aquifolium – is the only one this week that I actually purchased from a nursery, while in school in San Luis Obispo in the late 1980s. It is uncommon (and unpopular) here. I still dig it.P00808-2

3. Viola odorata – came from Santa Clara while I was in high school. (I thought) I wanted it because it blooms white. It is not very pretty, but I can not get rid of it. Violets should be ‘violet’.P00808-3

4. Pelargonium hortorum – is not the original that I found in a compost pile in Montara in about 1980, but is very likely the same ‘unimproved’ species or whatever it is. I found it downtown.P00808-4

5. Agapanthus orientalis – from Watsonville in 1992, is one of my two favorite agapanthus; because it is white, but is otherwise identical to my original blue agapanthus from the late 1970s.P00808-5

6. Amaryllis belladonna – came from Hoot Owl Creek in Oklahoma. It lived in the same garden with my Iris pallida! I know it is no more interesting that these others here, but it has history!P00808-6

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

https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/

Himalayan Birch

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The white bark of Himalayan birch is even more striking that that of European white birch.

Himalayan birch, Betula utilis ‘Jacquemontii’, must not be confused with the more traditional European white birch! If young trees get added to established groves of European white birch, they will never fit in. Their trunks stand vertically rather than lean casually. Their limbs are upright and angular instead of softly pendulous. Their bark is actually whiter.

Mature trees can get taller than thirty feet without getting much more than half as broad, and are relatively symmetrical for birches. The form of any single exposed tree is generally conical, although several trees together adapt to develop as picturesque groves with fewer interior limbs. The shade below is not too dark for lawn or moderately shade tolerant plants.

Maintenance is not exactly minimal. Vigorous young trees should be pruned and groomed annually, or at least every few years. Pruning should not be done in early spring when sap is likely to bleed from pruning wounds. Roots want to be watered somewhat regularly, even through the drought. When they fall in autumn, the two inch long leaves can be difficult to rake from fine gravel or bark.

Some Trees Are All Bark

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California sycamore bark is very distinctive.

Flowers provide color and texture. So does foliage. What is less often considered is that the bark of many trees and large shrubbery can be aesthetically appealing as well. Bark is usually thought of merely as something to cover up the trunks and limbs of the plants that provide all the colorful and textural flowers and foliage.

Coral bark Japanese maple and red twig dogwood (and yellow cultivars, which are  selectively bred varieties) turn color as they defoliate for winter. However, the color is limited to the twigs and smaller stems. Red twig dogwood often gets cut back at the end of winter so that it will produce more twigs for the following winter. Mature stems and trunks are not as interesting.

Palms and yuccas do not actually have bark, but are still texturally interesting. Giant yucca trunks are weirdly sculptural. Mexican fan palm can be  ‘shaven’ to expose lean trunks with a finely textured exterior, but are more often adorned with the intricately patterned thatch of old petiole bases (leaf stalks). Windmill palm is uniquely shaggy with coarse fiber.

Arbutus ‘Marina’ is a madrone that was developed for home gardens. It is compact and symmetrical, with finely textured flaking bark that reveals strikingly smooth cinnamon-colored bark beneath. Larger manzanitas can be pruned up to expose similar bark on a smaller scale. Smooth Arizona cypress looks much like other cypresses, but with strangely  smooth bark on vigorous stems.

The bark of almost all eucalypti is interesting for one reason or another. Even the notorious blue gum, which  gives other eucalypti a bad reputation, peels away in very long strips to reveal smooth bark that fades from green to pink to tan to gray before peeling away to start the process over again. Some eucalypti have blotched bark. Red ironbark has rich brown bark that is uniformly furrowed.

Lemon gum (eucalyptus) and various birches have strikingly white bark. Lemon gum bark is smooth. Birch bark peels away like paper. Because the trees are so slender, they can be planted in groups so that there are more trunks to display the distinctive bark. These are only a few of the many trees that can impress with mere bark.