This Parade Needs Some Rain

Now, this is something you don’t see every day in a chaparral climate.

The lack or rain has really gotten serious! This winter so far has been the driest ever recorded. The past two winters had already been unusually dry. Even when the rain starts, it will be considerably behind schedule. Some seriously torrential rain will be needed to catch up.

As much as we like to think of gardening as something that brings us closer to nature, it demands unnatural volumes of water. Only established native plants or plants that are native to similar climates can survive with the limited moisture that they get from rain. This is why gardens get watered as much as they do.

Lawns of course require the most water because their shallow root systems require such frequent watering, and also because their vast foliar surface area loses so much moisture to evapotranspiration (evaporation from foliar surfaces). Lawns are the first and most prominent of landscape features to succumb to water restriction. Flowering annuals are the next to succumb, because they too want regular watering, especially while they are not getting any from rain.

Fortunately, lawns, annuals and other plants that want an abundance of moisture need less now because they are dormant or considerably less active through winter. Besides, evapotranspiration is inhibited by cooler temperatures, shorter day length, and most of the time, by higher humidity. It is nothing like the warm and arid (minimal humidity) weather during longer days of summer.

Many large and established shrubs and trees can survive quite easily with very minimal watering or even none at all. Established oleander, bottlebrush and juniper may not be as vibrant without watering, but should survive. If they notice a lack of water at all, it would not be until they start to grow again in spring. Mature trees take even longer to notice a problem.

Deciduous plants that are now bare really do not consume much moisture at all and really only need enough moisture in the ground to keep their roots from desiccating. This will only be a problem if the soil is very sandy and drains too efficiently to retain adequate moisture, or if freshly installed plants have not had enough time to adequately disperse their roots into the surrounding soil.

Automated irrigation systems should still be operated only minimally or not at all through winter. However, because of the unusually dry weather, they may need to be used a bit more than usual for this time of year to keep some things from getting too dry.

Watering Trees Is Still Important

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.

Know The Time To Conserve Water

Automated irrigation is certainly not perfect.

In the wild, plants take water when it comes as rain. Native plants and plants that are from similar climates might be happy to get almost all of their water through winter, and almost none through summer. However, lawns and many other plants want some degree of water through summer. This is why most landscapes are irrigated.

Obviously, irrigation is unnatural. The main disadvantage is that it uses water that must be taken unnaturally from natural sources, which are often, and are presently depleted. The advantages (even during a drought) is that irrigation can be applied where needed, as needed, and when it is most appropriate.

Irrigation systems can be designed to deliver more water to plants that need it, and less water to those that are less consumptive. Watering by hose can of course be similarly tailored to the plants. The volume of water applied can be increased through warm and dry summer weather, and decreased or discontinued through winter.

Automated irrigation can be set to operate very early in the morning when no one is likely to be out in the landscape. The water gets used when the need for water in the home is minimal, so fluctuation in water pressure should not be a problem. If it operates early enough, irrigation can finish before anyone gets out to see it.

Furthermore, early morning also happens to be the best and most efficient time to apply water. Less water evaporates while the air is cooler and more humid. Therefore, more water soaks into the soil. Evapotranspiration (evaporation from foliage) is a bit subdued, so plants cycle through their own moisture a bit slower.

Many plants can just as easily be irrigated in the evening. This would allow even more time for water to soak in before the sun comes up. However, the problem for some plants and lawn is that moisture lingering on foliage all night long can promote the proliferation of all sorts of fungal diseases, including mildew.

Drip and similar irrigation is still the most efficient, simply because water is applied directly, with minimal evaporation. Broadcast irrigation from lawn sprinklers, especially fine mist, is much more susceptible to evaporation. Water evaporates as it gets sprayed through the air, and as it lingers on any wet surfaces.

Horridculture – Bad Guys

P91211Roots hold up trees. That is part of their job. They grow along with the trees they support, and disperse as necessary to maintain stability. Trees grown within the confinement of cans (pots) or boxes, and then installed into a landscape, are typically staked temporarily until their roots adequately disperse and stabilize. Once unnecessary, stakes and bindings must be removed.

Mature palms that get relocated are supported temporarily by guy wires. They are just too big to be supported by stakes. Because palm trunks to not grow any wider as at they grow taller, they are not damaged by the sorts of bindings that would damage the fattening trunks of other trees. Like stakes on other trees, guy wires must be removed as they become unnecessary.

Although they can be appropriate in unusual circumstances in which stakes would not be practical, guy wires are rarely used on trees that are not palms. Mature trees that get relocated can be guyed if too big to be supported by stakes. Because trunks and limbs of such trees expand (circumference), it is more important for guy wires to be remove when they become obsolete.

As useful as guy wires can be, they are more often used improperly or inappropriately. Firstly, those who install them rarely do so correctly, with the wires or cables as straight as possible between each end. Cabled anchors are usually pounded into the ground perpendicularly to the direction of the cable, so that the cable merely slices through the soil when tension is applied.

Once installed, cables are very often left in place long enough to constrict the growing trunks or limbs that they are attached to. Cables that apply too much tension or limit the motion of the trees they support (in the breeze) for too long will actually inhibit root dispersion. Trees will only become as stable as they need to be. Besides all this, lingering cables are just plain unsightly.

The cabled trees in these pictures demonstrate another set of problems that should be corrected by simple and necessary pruning, and comparably necessary adjustment of the automated irrigation. Guy wires should most certainly not be necessary for such mature trees of this species, and will interfere with necessary root dispersion without remedying the primary problems.

Firstly, the trees are too low and dense. Even if stability were not a concern, they should be pruned for a bit more clearance above the patio to the right of the picture, and perhaps allow a bit more sunlight to the plants below, even if only temporarily. More importantly, pruning would temporarily decrease weight and wind resistance of the canopies while roots adapt accordingly.

Secondly, the landscape is getting irrigated too much, even for the ferns in the background. This maintains soil saturation so that stabilizing roots can not disperse into deeper strata. Roots that might have extended deeper earlier will drown and rot. Until this happens, excessive irrigation promotes heavy superfluous growth that the compromised root system can not support.

Automated irrigation should be disabled for winter, and operated only manually and minimally if the weather stays dry long enough for the ferns to get drier than they are comfortable with. It can be adjusted accordingly when reactivated in spring. Even before that happens, and roots disperse, the guy wires can be removed as soon as these trees get pruned as they should be.P91211+

To Mulch Is Not Enough

60727thumbMost plants would prefer the real thing; how they do it in the wild. They drop their leaves, flowers and twigs. Deciduous plants do it mostly in autumn. Evergreens might spread it out through the year. The debris accumulates on the ground below, and decomposes at about the same rate as it accumulates. There is no one there to clean it up. Yet, the natural ecosystems know what to do.

The plants that produce the debris use the nutrients produced by its decomposition. So, with the help of the many microorganisms in the soil, they recycle their own trash. To exploit this resource most efficiently, feeder roots tend to congregate near the surface of the soil where the nutrients are. Because the debris also insulates and shades the soil surface, roots are comfortable there.

Densely forested ecosystems produce the most debris. Many smaller plants in such ecosystems may disperse their roots exclusively into decomposing debris without reaching into soil below. In desert ecosystems, where such debris is minimal, roots are mostly dispersed much deeper to avoid the hot and dry soil surface. They wait for recycled nutrients to leach to them through the soil.

Redwoods, cypresses, many pines and most eucalyptus produce unusually thick layers of debris that decompose slowly. This technique inhibits or prevents the germination of seeds of potentially competitive plants. So, in other words, these trees and other plants had this, as well as moisture retention, soil insulation and nutrient recycling, all figured out long before we knew about mulching.

After we put so much work into raking and disposing of foliar debris that would otherwise accumulate in our gardens, it is ironic that we sometimes need to apply seasoned mulch to compensate for the lack of organic material on the surface of the soil. (Unseasoned mulch draws nitrogen from the soil to sustain its own decomposition.) It does more than merely improve the appearance of otherwise exposed soil. Mulch helps unnatural landscape environments function a bit more naturally.

Horridculture – All Wet

P90327Regardless of their individual innate requirements for water, new plants need to be watered very regularly immediately after they are installed into a landscape. As they mature and disperse their roots, the regularity of supplemental watering becomes less important, and ‘drought tolerant’ plants may not need to be watered at all. Maturing larger trees generally get what they need from the landscape around them.
Automated irrigation systems that are designed for new landscapes are designed for what the plants need while the landscapes are new. As the landscapes mature, the irrigation systems may need to be adjusted accordingly. Drip irrigation or bubblers that were needed to water new trees while they were young and confined should be moved farther from the trunks of the trees as roots disperse, and should eventually be removed and capped.
This is very important, since water applied directly to the trunks of some maturing trees will promote rot and other disease. For some, it promotes buttressing of roots that can displace concrete or other landscape features. If nothing else, it is just a waste of water.
Whoever installed the irrigation to this young London plane tree knew how to do so properly. The bubbler was likely over the confined root systems of the formerly canned tree just after it was installed. It is installed in such a manner that it could have been moved over as the tree grew, replaced with some sort of drip irritation hose to curve around the tree (if such a device had become necessary), or simply removed.
Now that the tree is as mature as it is, the bubbler should simply be removed, and the riser (where the white ‘L’ is) should simply be capped. The tree gets what it needs from the rest of the landscape around it, and really does not need much water anyway. It could probably survive without any supplemental irrigation at all. The bubbler is really just wasting water.
However, because so-called ‘gardeners’ are what they are, the bubbler remains, attached to an unsightly bit of exposed pipe, and wasting water on the base of the trunk of the sycamore. Because this tree and associated bubbler are right next to a parking spot in a parking lot, the pipe is very likely to get stepped on and broken every once in a while. In fact, the fresh Teflon tape on both ends of the pipe suggest that it was repaired quite recently, rather than removed.
Fortunately, the sycamore will not likely be damaged by water applied directly to the base of the trunk.

Horridculture – Car Wash

p90116Much of California is chaparral. Much of what is not chaparral is full blown desert. Some coastal climates gets quite a bit of rain; and some climates up in the Sierra Nevada are among the snowiest places in America. Generally though, the most populous and most agriculturally productive parts of California do not get much water to spare.
I certainly do not mean to say that we do not get enough water from rain and snow. We get what the region has always gotten longer than anyone can remember. Those who do not want to live in chaparral or desert need not live in California.
If there seems to be insufficient water for all of us to share, it is merely because there are too many people wanting too much of it, and too many who profit from controlling and selling it to them. Some of us conserve water and landscape accordingly. Others have no problem with vast overly irrigated lawns.
As a horticulturist who grows horticultural commodities, I use what I must for my work. I would prefer others to conserve water in home gardening, but can not complain if they choose not to. If they do not mind paying for excessive consumption of water, that is their prerogative. If rationing becomes necessary, and they do not want to pay fines, their expensive landscapes will be damaged or ruined while mine will survive.
However, it is difficult to not be disgusted with some of the waste I observe in some landscapes. One of the landscape companies that I ‘tried’ to work for years ago regularly watered almost all of their landscapes so excessively that trees succumbed to soil saturation. We then charged significantly to remove the dead or dying trees that we were hired to take care of; hence my ‘Horridculture’ articles on Wednesdays.
We have been getting quite a bit of rain here recently, and are expecting more rain through the next several days. The cloudy blue sky in the background of these pictures was the most blue sky we had seen in quite a while, and it lasted for only a few hours. The lawn in the park here is too swampy to walk on. Just in case there is a slight possibility that there is a small scrap of it that is not sufficiently swampy, it is getting watered generously.
I know mistakes like this happen, and that those who maintain this particular park are seriously overworked and understaffed. I am annoyed about this anyway. With all the modern technology available, why does the irrigation system not know that it is raining so much? If the irrigation system lacks the sort of technology that allows it to monitor the weather, why has no one told it that it is raining so much? If it can not be contacted by telephone, why does no one who know what the irrigation schedule is stop by to disable the system, or just close valves?! Okay, so I know they are understaffed, so I can not complain about it too much.
Nor should I complain about the parking lot getting watered. I know how easy it is for a sprinkler to get knocked out of adjustment. Besides, the windows are rolled up.
However, I am now a bit more concerned about the weather. Too much rain can cause flooding and mudslides. I already know what the forecast is; and now that the car got washed, the rain could get disastrous!p90116+

The Humongous Fungus Among Us

04Is this Armillaria mellea, the dreaded oak root rot fungus? I really do not know. All the elements are here. The stump is that of a coast live oak. Bellow the stump there are the remains of roots. Those necrotic roots are undoubtedly decomposing as a result of rot. That rot is undoubtedly associated with this fungus. Furthermore, it fits the description of oak root rot fungus. The toasted spots were probably caused by weathering as the mushrooms started to develop while the weather was still warm and dry.

Now that the soil and rotting wood are damp from rain, this fungus is really proliferating. The individual mushrooms within the soccer ball sized mass were only about as big as those at the lower left margin of the picture just prior to the rain. They do not last long, and might become gooey black slop after only a few sunny days. The stump may continue to rot for a few more years. It is out of the way, so there is not need to get rid of it.

It annoys me when landscape professionals tell me that a particular spot in the region has oak root rot fungus. Of course it does. It is everywhere. It is quite natural here.

Oak root rot fungus is justifiably dreaded. It can easily kill the most majestic oaks that have survived for centuries.

However, most of the problems with oak root rot fungus in landscape situations are caused by supplemental irrigation and other gardening techniques. Oaks that have survived on natural seasonal rainfall for centuries are much more susceptible to rot if their roots are kept continually moist by the irrigation needed to sustain other plants added around them. Roots that get severed for the installation of pavement or building foundations are likewise much more susceptible to rot, particularly in spots where drainage from roofs or paved surfaces enhances soil moisture.

For this particular pathogen, gardening is more often the problem.

When It Rains It Pours

51118thumbFor those who do not remember ancient history, this wet stuff that fell from the sky recently is known as “rain”. It used to be more common, particularly through winter. It has an unfortunate way of getting everything exposed to it quite wet. It makes soil muddy. Yet, rain has many attributes. It is composed of water, so provides much of what irrigation systems have provided for so long in the absence of rain.

Most of us have already been using less water around the garden than in the past. Some plants have suffered, and a some may have died. Surviving lawns are probably not as green as we would like them to be. Just when we think that the garden can not get by with any less, the weather takes over. Even sporadic rain mixed in with mostly sunny weather provides significant moisture.

Not only is more moisture falling from the sky, but the plants and lawns that want it become less demanding through autumn and winter. Evergreen foliage loses less moisture to evapotranspiration (evaporation from foliar surfaces) because it is exposed to less sunlight during shorter days, and because the air is cooler and more humid. Deciduous plants drop their leaves, so do not lose moisture.

Even plants that are sheltered from rain by eaves will need less water because of the cool and humid weather, and shorter days. Some potted evergreen plants that are disproportionately large relative to their pots will likely want to be watered between the rain, only because their roots are so confined. Potted deciduous plants may need their soil moistened if the weather stays dry long enough for the soil to get dry.

Automated irrigation systems need to be adjusted for the changing weather. Some systems may need to be adjusted a few times. By the time the weather gets reliably rainy and cool later in winter, some irrigation systems can be temporarily disabled until the weather gets warmer and drier in spring. Not only does this conserve water; it also makes over-watering and soil saturation less likely.

Watering Starts Where Rain Finishes

70607thumbFor a while last winter, it seemed like the rain would never stop. Obviously, it did. The warm spring weather that followed helped plants to take advantage of the rare surplus of moisture. Desert wildflowers were more colorful than they had been in many years, and maybe since 1983 in some areas. Now the weather is back to normal for here, and we must water our gardens accordingly.

There is nothing natural about irrigation (watering); but then, there is nothing natural about gardening or landscaping. Most of the plants in common landscapes are not native. They were imported from vastly diverse regions with very different climates. Because this happens to be a semi-arid ‘chaparral’ climate, most plants want more moisture than they would get here naturally from rain.

Adapting unnatural irrigation to unnatural landscaping sounds easy enough. The problem is that the many different types of plants from so many different climates each want something different. Also, some plants need unnaturally frequent irrigation to sustain unnatural behavior. For example, lawn grass that would naturally go dormant after a dry summer needs water to stay green all year.

Lawn grasses have finely textured roots near the surface of the soil, so want frequent irrigation. Trees within lawns might want larger volumes of water to reach lower roots, but do not like frequent irrigation that keeps the surface of the soil moist. The sort of regular irrigation that is good for lawn promotes shallow tree roots that ruin lawns and pavement, and are not exactly ideal for stability.

Automated irrigation is usually set to operate very early in the morning, and finish before anyone in the home is likely to be outside, or using much water inside. (Other water use can compromise pressure.) Less water evaporates before the sun comes up. Watering before midnight might seem like a better idea, but keeps foliage wetter longer, so might promote fungal diseases such as mildew. Frequency and duration (volume) of irrigation require occasional adjustments to adapt to the weather.