Natives Are Right At Home

Some native plants should stay wild.

Long before people came here and imported exotic (non-native) plants from all over the world, native plants had been perfectly happy without any pruning, watering or fertilizing. They had always been perfectly happy with local soils, local climates and even occasional wildfires. Many are still happier in the wild than in seemingly more comfortable refined gardens and landscapes.

It really makes sense though. Most exotic plants need to be watered because they are from climates that naturally get more rain. Some want to be fertilized because they are from regions with different soil types. Some plants prefer cooler winters. Others want more humidity. They crave what they would get in their respective native homelands.

However, plants that are native to California are not necessarily native to here. California is a big place with all sorts of climates and soils. For example, the desert fan palm that is native to warm and dry Palm Springs would not be happy in cool and foggy San Francisco. Big leaf maple that likes the cool winters of the Siskiyous does not like the mild winters near the coast of Los Angeles. The best natives are those that are native to a particular region, or similar region.

Also, there are a few native plants that are not so easy to accommodate in every home garden. Both the giant sequoia, which is the biggest tree in the world, and the coastal redwood, which is the tallest trees in the world, are native to California. Even if the local climate is a good fit, the space available may not be.

One of the most difficult problems for so many natives though, is that they are sensitive to the regular watering that most exotic plants require. The regular watering that lawn needs just to survive is enough to rot the roots of plants that do not expect any water between spring and autumn.

Santa Barbara daisy, penstemon and various salvias are some of the favorite native perennials. Wax myrtle and the various ceanothus and manzanitas are interesting shrubbery. Western redbud and toyon can be big shrubs or small trees. California sycamore and various oaks are big trees for big spaces.

Start Young Trees Off Right

Recovery is difficult for abused trees.

Young trees are so impressionable. Too much water can damage their roots, or cause them to disperse too shallowly. Improper pruning can disfigure their branch structure, and ultimately compromise structural integrity. Improper staking to keep them stable can actually interfere with development of stabilizing roots, and interfere with trunk development.

Newly planted trees will of course want to be watered from spring to autumn for at least the first year, and more likely for a few years. Those that will eventually be less reliant on watering as they mature are actually the most demanding while young, because their confined roots are not yet adequately dispersed for self sufficiency. The problem is that too much water can keep lower soil too saturated for new roots to disperse into. This causes roots to instead disperse closer to the surface of the soil, which is not only unhealthy for the trees, but puts the roots closer to pavement, other plants and any other features that they can eventually damage as they grow.

Many young trees should be pruned as they grow to eliminate structural problems, and to instead promote good branch structure. The problem is that improper pruning can actually cause structural problems that will be with the victimized trees for the rest of their lives. Pruning should leave no stubs that will take longer to compartmentalize (heal), or that might produce vigorous but weakly attached new stems.

Stakes are unfortunately necessary to stabilize new trees. The problem is that the trees can become so reliant on stakes for support that they do not develop enough trunk strength to support their canopy without stakes. That is why trees should be tied loosely enough to their stakes to be able to move at least a little in a breeze. Nursery stakes (that trees are bound to for a straight trunk in the nursery) should be removed when sturdier stakes are added.

New trees are naturally a bit more distressed than mature trees that have settled into their environment. They are consequently more susceptible to disease and insect infestation.

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

50812thumb
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

P00418K-1
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 – 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+

Do Not Forget Potted Plants

30918thumbAside from all the seasonal raking and dormant pruning, there is not as much to do in the garden as there was earlier in the year. Lawns do not need much mowing. Hedges do not need much shearing. Untimely mowing and shearing can actually damage lawns and hedges. Watering, which was so important while the weather was warm, is now rare in the cool weather between rain.

Watering is now so infrequent that the few plants that still need it sometimes do without. Plants that are merely sheltered by eaves probably do not mind so much because their roots are dispersed beyond the eaves. However, potted plants that are sheltered by eaves do not have that option. It may take a while in the cool and damp air, but they can slowly get uncomfortably dry.

Watering sheltered potted plants is too easy to forget about while everything that is not sheltered is getting soaked by rain. It is even more easy to forget because it is so infrequent. Things just do not dry out like they do in summer. Also, plants are less active, and many are dormant and defoliated, so really do not lose much moisture to evapotranspiration (evaporation from foliar surfaces.)

In fact, overzealous watering can be just as detrimental as neglect. Soil saturation may not be as immediately dangerous as it would be during warmer weather, but eventually kills roots. Even with adequate drainage, soil moisture can linger if plants do not consume it. Determining how much water is needed for sheltered potted plants may not be as simple as it should be.

Larger plants in smaller pots want more water than smaller plants in larger pots. Those that are exposed to wind will get dry faster than those that are protected. Hanging pots dry out the fastest. Ironically, drought tolerant plants that need the least water in the ground often want the most in pots. They are the most reliant on extensive root dispersion, which is not possible in confinement.

Some potted (frost tolerant) plants might get slightly relocated out into the weather so that they get the rain that keeps the rest of the garden well watered through winter.

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.

Happy Easter!

P80401Happy Easter!

This is one of those holidays when no one should work, which is why I wrote this a few days ago, and scheduled it to post today. I hope you are not reading this today. You have more important things to do. Lent and the forty days of fasting that goes with it are over, so you can eat all the Easter eggs and anything else you want.

The only work that should be done today are chores that can not be delayed until tomorrow. With the weather warming (at least in our region), watering might be one of those chores. For most parts of the garden, this might be the first watering since autumn. Although the rain has been meager, cool weather had kept things damp until now. Resuming watering is typically an easy task. It sounds simple enough. Water is water – right?

I get all sorts of unexpected questions in my work. In autumn, I sometimes get asked about trees that were planted in spring or summer that are suddenly turning yellow and dropping leaves; and must explain that the seemingly sickly trees are merely deciduous and defoliating for winter, which can be a major disappointment if evergreen foliage was needed. Then there are the questions about the five pound kumquat that is actually a shaddock fruit on an overgrown sucker (understock from below the graft).

About this time, many years ago, I got a call about a sad #5 (5 gallon) pistache street tree that had been planted while bare during the previous autumn. The client who planted it wanted to do what was best, so planted it in autumn so that it could settle in slowly while dormant through winter, and get an early start dispersing roots in spring. Generous rain that year provided more water than the tree needed through winter. As the rain ran out, and the weather warmed, buds swelled and began to pop. The client who planted the tree was very careful to water it when she thought it was necessary, but the new foliage immediately started to get discolored and distorted. Her remedy was to give it more water, but the health of the tree continued to decline as quickly as it was trying to foliate.

I asked all the typical questions about the tree, but only determined that it was not lacking water, and probably was not getting too much water. The symptoms exhibited by the foliage suggested soil saturation and poor drainage, but the soil drained well, and the roots seemed to be firm. I was baffled, until the client mentioned something very unexpected. I had to ask her to clarify.

She loved the tree so much that she wanted to give it the best water she could obtain. Every day, on her way back from downtown San Jose, she stopped at the Cathedral Basilica of Saint Joseph to procure a gallon of Holy Water to water it with!

That was a new one. I then had the sad duty of explaining to her that her devotion to the tree was what was killing it. The Holy Water that she had so diligently been giving it was saline. After Holy Water is blessed, some gets stored for upcoming baptisms, and the rest gets blessed salt mixed into it, mainly for sanitation. It was this salinity that was so toxic to the tree.

After a lot of fresh water was rinsed through the root system, the tree started to recover almost immediately, and eventually resumed healthy growth. The client telephoned the following autumn as the tree was coloring to inform me that it had been restored to good health, and grown through summer as if nothing had ever happened.