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.

Ponds Cannot Conserve Water

Aquatic plants provide shelter for goldfish who eat mosquitoes.

During a drought, there really is no way to use less water in a garden pond. Aquatic plants can not survive without adequate water; not to mention fish! Pumps that circulate water must stay submerged to operate properly, and to not get damaged by operating without water. Some degree of water needs to be added regularly to compensate for evaporation.

Water does not evaporate from below the surface of the water. Therefore, depth is irrelevant to water loss. The area of the surface of the water is more important. Sunlight and wind accelerate evaporation. So do fountains or pumps that broadcast water through the air for circulation. Aquatic plants that stand above the surface of the water lose water to evaporation from foliar surfaces.

Yet, most of us who enjoy gardening cannot resist growing aquatic plants if a pond is available. Not only do they provide distinctive foliage and bloom, they also provide shelter for goldfish or minnows that control mosquitoes. They keep water clearer by competing with algae.

Submerged aquatic plants, like anacharis, do everything in the water. Some do not even need soil to root into. Because they do not come above the surface of the water, they do not affect evaporation. None of the floating plants, like water hyacinth, water lettuce and duck weed, have any use for soil either, although some of the leafiest sorts can accelerate evaporation.

Water lilies and lotus are emergent aquatic plants, which naturally live in mud on the bottom of ponds, but develop foliage and flowers that emerge and float on the surface. Although they have the potential to affect evaporation, most are more likely to inhibit evaporation by keeping water shaded. In garden ponds, they must be potted, and should be under at least a foot of water.

Relative to other aquatic plants, bog plants such as cattails, aquatic cannnas, and blue or yellow flag iris consume the most water from saturated soil at or just below the surface of a pond. They produce the most foliage that stands well above the water. Like water lilies and lotus, bog plants need to be potted, but with the tops of their soil barely below the surface of the water.

Pots should be low and wide, and obviously do not need drainage holes. Unnecessary holes only spill a bit of soil, and allow roots to escape and grab onto the bottom of a pond. Good old fashioned soil (yes, dirt from the garden) is fine. Good quality potting soil merely floats away.

Summer Is Not For Planting

New plants are less reliant on irrigation if installed at the beginning of the rainy season.

Autumn is the time for planting. Cooling weather slows plants down so that they do not mind disruption so much. Increasing rain (hopefully) keeps the soil evenly moist while roots slowly disperse. The combination of cooling weather, increasing rain and shorter days keeps plants well hydrated so they can slowly ease into spring.

Why is this important now? Well, it probably is not important. It merely demonstrates why this is not the best time for planting. Only a few warm season annuals and vegetables get planted this time of year. Seeds for certain autumn vegetables get sown now. Otherwise, more substantial plants should wait until autumn if possible.

Mid summer in some ways is the opposite of autumn. While the weather is warm, plants are too active to be bothered. Even minor disruption can be stressful. Soil moisture provided by irrigation is often too irregular and unreliable for dispersion of many new roots. There is less time to recover from stress during shorter nights.

Smaller plants and seeds survive summer planting better than larger plants do. Seeds need to disperse all new roots anyway, so they  will adapt to what they get. They certainly need regular watering, but are quite talented at putting their roots wherever the moisture goes. With a bit more time, smaller plants will do the same.

Larger plants have more difficulty with the planting process because they need to disperse so many more roots to get established. When they get planted, all their roots are initially confined to the volume of media (potting soil) that they were grown in. They are susceptible to whatever happens within  that limited volume.
For example, a small plant in a four inch wide pot is initially confined to less than sixty-four cubic inches of soil. It can double its soil volume to one hundred forty-four cubic inches by merely dispersing roots less than one inch laterally. A tree in a 24-inch wide box needs to disperse roots ten inches laterally to do the same!
It would seem that drought tolerant plants would be less susceptible to the stress of planting in summer.

However, they are more sensitive because they are so reliant on extensive root dispersion. Until they disperse their roots, they actually need to be watered as frequently as other plants do.

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.

Water Feature


Brent Green, my colleague down south, is a renowned landscape designer of the Los Angeles region. His landscapes are spectacular. You might not know it by all the mean things I say about Brent and his work, but his clients know otherwise. He makes the outdoor spaces around their urban homes seem like they are in serene and thickly forested jungles hundreds of miles away.

Well, . . . generally. That is what the landscapes look like to me. Some clients prefer simpler or sunnier gardens. What I often perceive as superfluous vegetation is there to obscure adjacent residences or other undesirable scenery. It is not as if neighboring residences are unsightly. They are obscured merely to provide privacy and a sense of solitude in a very crowded region.

While designing a landscape that is appealing to the senses, it is helpful to eliminate or at least obscure some of what is unappealing. This applies to more than visual aspects. In some urban areas, ambient noise is a constant reminder of all the hectic chaos just outside of a landscape. Dense vegetation that obscures undesirable scenery muffles some or even most, but not all of it.

That is why Brent incorporates what he refers to as ‘water features’ into many of his landscapes. The noise of the splashing water partly obscures ambient noise. Because Brent’s home is just a block from the Santa Monica Freeway, there are four small ‘water features’ in the gardens! That is excessive of course, and more than what larger landscapes in quieter neighborhoods get.

These water features seem silly to me. I find the mostly monotonous noise of the Santa Monica Freeway to be no more annoying than the sound of the splashing water. I might appreciate water features more if they did my laundry. However, there are a few water features where I work, even though ambient noise from the outside is rather minimal. There are no freeways.

Fern Dell Creek in the video above flows into the confluence where Bean Creek flows into Zayante Creek. Zayante Creek Flows into the San Lorenzo River just a short distance away. Two Redwood Springs Creeks, which are comparable to Fern Dell Creek, flow into Bean Creek just a short distance upstream from the confluence with Zayante Creek. All this water can get noisy.

Fern Dell Creek and the two Redwood Springs Creeks are short streams that flow from springs, so their minimal flow does not fluctuate much at all, even after heavy rain. Bean Creek and Zayante Creek have more substantial watersheds and carry significantly more water, especially after heavy or prolonged rain. Unlike Brent’s water features, we can not turn any of them off.

Horridculture – That’s Just Swale

P90424Building and environmental codes are so ridiculous. So much of what I would want in my home is now illegal. So much modern technology that I do not want is now required. Fireplaces and wood stoves are not allowed. Overly elaborate electrical systems to serve every room are necessary. I would prefer a technologically simple home comparable to those built more than a century ago, but am prohibited by law from ever constructing one.
The area outside of a home is no easier to work with. Dead trees inhabited by the wrong sorts of woodpeckers can not be cut down. Excavation can be prohibited if a particular beetle happens to be in the way. Even some of the increasingly combustible trees and overgrown vegetation have more rights on my land than I do. Now, I am a horticulturist; so I know more about vegetation management than the treehuggers formulating these laws.
Even some of the weather has more rights than people do. In some municipalities, rain that falls onto a property has the right to percolate into the soil. Rain water that drains from roofs and pavement must be provided with ‘swales’ or basins where it can do so. It can not be evicted into old drainage systems that drain into local creeks and rivers. However, such rain water must not be detained in tanks for use in the landscape through summer.
The picture above shows part of a new landscape in the middle of a new parking lot at a newly constructed building. It looks simple for a reason. It is a pair of swales. The meadow grasses conceal a pair of surprisingly deep ditches on either side of the central walkway. Rain water drains here to percolate into the ground. The soil below the walkway might have been replaced with coarse gravel to promote drainage into that area as well.
Do not park a car at the curb and try to step from the curb into a swale to get to the walkway! You could get hurt. As I mentioned, that grass is concealing ditches that are deeper than they look. It is safer to walk through the parking lot to a large paved patio like area that is out of view behind where the picture was taken from. The other option is to walk away from the building to the far end of the walkway, but really, who would do that?
Why is the walkway even there? I really don’t know. There are no curbs on it, so anyone in a wheelchair who feels so compelled to go to the far end to use it could get seriously hurt by tumbling off the edge while trying to get out of way of someone going the opposite direction! The swales are snares for walkers and baby buggies too. Perhaps the walkway is merely bait. What are the surveillance cameras really for? What sick entertainment!

San Lorenzo River

P90210It may not look like much, but before all the rain started, the San Lorenzo river was shallow enough here to walk across. The water was clear and barely flowing. It is impossible to guess how deep it is now. It looks like cafe au lait, and is certainly flowing better than it had been. The watershed is less than a hundred and fifty square miles, so all this water is not coming from very far away.
The first picture above, of the San Lorenzo River flowing south to Santa Cruz and the Monterey Bay, was taken from the western of the two windows on the south side of the Felton Covered Bridge. Experts believe this to be the best of the four windows. My Mother has an old black and white picture of my older sister, my younger brother and I looking out from this window when were just little tykes. There was a railroad bridge out there a long time ago. Only concrete foundations remain.
The second picture below, of the San Lorenzo River flowing from the Santa Cruz Mountains beyond, was taken from the western of the two windows on the north side of the Felton Covered Bridge. The San Lorenzo River flows south on this side too!
It has been raining rather well here. Boulder Creek, which is at the far north end of the San Lorenzo Valley, gets more rain than most places in California, and far more than the rain shadow region on the inland side of the Santa Cruz Mountains. Local rain does nothing for the water supply of the rest of California, but is a good indication that snow is falling in the Sierra Nevada, where most of the water for much of the rest of California is stored in the snowpack.P90210+

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+


P80103+For those who do not remember what ‘rain’ is, it is, it is those odd drops of water that fall so mysteriously from the sky in other regions. We get it here too, just very rarely, and almost exclusively within a limited season centered around winter. Rain tends to be affiliated with storms. The last storm moved through here last spring.
Rain may not be much to look at, and is nearly impossible to get a picture of, but it adds up to become a very important commodity known as ‘water’. Some believe that California does not have enough water. We natives know that there is actually plenty of water, but merely too many people in need of it, and a few of those many who capitalize on that need. Anyway, I did not even try to get a picture of the rain that is falling so nicely now, but recycled this old picture of a small volume of water in what is known as a puddle, which is merely an accumulation of water within a low spot on a flat surface.
As unpleasant as rain is to work in, we are very pleased to get it. The sky is rinsed of smoke, and despite the unpleasant news that rain will interfere with searching for remains of those killed by the Camp Fire, there is also the excellent news that the rain is falling over a large area, and making forests significantly less combustible. The formerly crispy forest is again lush and damp and sloppy. What had been a Dust Bowl down where we dump greenwaste is now an epic mud pit! Everyone here is delaying other work to clear drains on roads and roofs. The first storm of the season is always something to celebrate.

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.