Leaves are the original solar panels. They collect solar energy, and convert into useful resources. Some of those resources get converted into other resources that are good for human consumption, such as fruit, vegetables, lumber, firewood and oxygen. However, one resource that leaves do not produce is electricity.
That is why the big solar array pictured above was installed over a big parking lot. There are a few of these arrays in this parking lot, and more in other nearby parking lots. Many trees were cut down to accommodate them. People who work nearby can use the electricity more than they could use vegetation, or anything that vegetation could produce within this area.
Shade trees are nice over parking lots, but are not necessary over a parking lot that is shaded so thoroughly by such big solar arrays. After parking during rainy weather, an umbrella is only necessary between the solar arrays and the adjacent office buildings. There are no more fallen leaves to clean up. Pavement and curbs will no longer be displaced by growing roots.
The red gum that is also pictured above, under the solar array, is not so impressed. It likely grew from a root of a red gum that was removed so that the solar array could be constructed. Sadly, it must be cut down again, not only because it is under the solar array, but also because it is against the sidewalk. It has clearance problems both above and below.
It is rather ironic that even after all the trees that formerly shaded this parking lot were cut down for the installation of this solar array, this young red gum that is so determined to survive can not stay. I can not help but wonder what this young red gum thinks of green energy.
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.
The easiest way to propagate new fig trees may seem to be violent, but it works. Basal shoots that grew last year from the roots near the trunks of ungrafted trees can simply be torn out of the ground with as many attached roots as possible. These shoots can then be planted directly wherever new trees are desired, and watered in. Larger shoots may need to be dug out, and might do better if pruned down to just a foot or two tall when planted. Smaller shoots can be potted to grow through next summer, and then get planted in the ground next winter.
Tearing the shoots off in this unpleasant manner is effective for two reasons. It gets the most roots for the shoots to help the grow into new trees. It also removes more of the burl growth that produces the shoots than simply cutting the shoots neatly. Even if copies of the original tree are not desired, the basal shoots must be removed anyway. Simply pruning them away leaves more burl growth so that more shoots grow back next summer. Ideally, well maintained trees should actually not produce basal shoots.
Fig trees are innately easy to grow from basal shoots or cuttings while dormant through winter. Basal shoots, even those that get pulled without any obvious roots, will develop roots more efficiently than stem cuttings that were never in contact with the soil. However, if no basal shoots are available, stem cutting work just fine. Furthermore, grafted trees (which are quite rare) can only be copied by cuttings from above the graft. Basal shoots from below the graft will only produce copies of the understock.
Just as unwanted basal shoots and cuttings from pruning scraps can be grown into fig trees, overgrown perennials in need of thinning can be divided to propagate more of the same. Lily of the Nile, red hot poker, daylily, mondo grass, African iris, terrestrial yuccas, some ferns and some grasses are not only easy to propagate by division through winter, but many perform better if divided every few years or so, before they get too crowded. The common giant yucca develops big trunks instead of clumping shoots, but can be propagated just as easily from big cuttings.
Most of the advantages of bare root stock are obvious. Bare root stock is less expensive and easier to work with in regard to installation and pruning to a desired form. What some of us may find difficult to understand is that it actually gets established into a new garden more efficiently than canned (potted) nursery stock does. As incredible as it seems, there are a few simple reasons why.
Instead of dispersing roots within the confinement of cans, bare root stock disperses roots directly an extensively into the soil into which it gets planted. Their initial deficiency of roots encourages them to do so quickly. Roots of canned stock must recover from confinement. Their new roots may be hesitant to leave the comfort of the extra rich medium in which their original roots developed.
The holes dug for planting bare root stock need not be much wider than the roots can be spread apart, and no deeper. If too deep, newly planted stock will sink as the loosened soil below settles. Grafted plants must not sink enough for their graft unions to be below grade. A cone formed of firmly pressed soil at the bottom of a planting hole can be useful for spreading roots out evenly over.
Rich soil needs no amendment. If compost is added to loosen dense soil, it should be as minimal as practical. Too much amendment will tempt roots to stay close rather than dispersing remotely. Fertilizer is not necessary immediately after planting. However, because the soil does not stay very cold here, and roots start growing before spring, mild fertilizer can be applied shortly afterward.
Finally, most bare root stock should be groomed and probably pruned after planting. Fruit trees are often sold with only minimal prior pruning. Superfluous stems function as packing material that buffers the ravages of transportation, and also provide more options for preliminary structural pruning. Aggressive pruning of plants that benefit from it concentrates resources for growth in spring.
It has been almost a month since one of three small but sculptural and very prominent coast live oaks at work was destabilized by . . . well, children. They were climbing on it, as most good children should do. There were a few of them; and the tree is old and deteriorating. All three of the trees actually grew from the same rotten stump of a tree that was cut down decades ago.
To salvage the tree, I pruned off as much of the foliar canopy as possible. This eliminated some of the weight that the trunk needs to support, as well as decreased some of the resistance to wind, which exerts leverage against the compromised root system when wind blows. Sawhorses were placed under the trunk, and one of the others, to prevent them from sagging any lower.
Props that were fabricated to be more permanent then the sawhorses were installed last week. They do not actually support or even touch the trunks, but are there to prevent the trunks from sagging any lower. If the trunks start to lean on the props, I will prune a bit more weight off. If that doesn’t work, the props can be moved a bit farther out, where the trunk are higher.
Hopefully, the old root system of the destabilized tree was not so severely damaged that it can not recover. If it does recover, and the trunk is not supported by the new prop, the tree will need to eventually regain stability. It will be a tediously slow process. Because the trees are already so mature and disfigured, the props will likely never be removed, regardless of recovery.
The first picture above show the destabilized tree outfitted with a new prop. The second picture below shows the other tree that was outfitted with a new prop just because it is so likely to become destabilized.
Most 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.
Regardless 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.
Today’s episode is brought to you by the letter ‘T’.
This is not Sesame Street.
Nor is this freshly painted concrete ‘T’ a monogram that designates the garden as mine. Even I am not ‘that’ vain.
It is part of a sign at the train depot. There happen to be enough of the right letters for my last name. I suppose that with a pry bar and a shovel, I could be ‘that’ vain.
There is no ‘Y’, so my first name would not work, particularly in conjunction with my last name, which would take the only ‘T’ and ‘O’ available. Am I really vain enough to be putting this much thought into this? Oh my!
For right now, I should only be concerned with keeping the vegetation clear of the sign. The amaryllis foliage above barely flops into it. The overgrown photinia hedge behind the amaryllis was just removed. The arborvitaes that will be installed to replace the photinia hedge will not likely get wide enough to ever reach the sign. They will be set several feet back. We are still trying to decide what to install between the arborvitaes, which will be far enough from each other so that they will not become a continuous hedge like the photinia were.
You would not believe how many bay trees and valley oak trees were trying to grow amongst the photinia! They ranged in size from fresh seedlings all the way up to a nearly six inch wide coppiced stump of a valley tree that was cut down a few years ago. There are still a few small oaks that must be removed nearby. We want to remove them while we are working on the site, and before they get big enough to displace the concrete letters with their roots.
Root pruning is nothing new. It is done more commonly than we think about for many aggressive perennials like lily-of-the-Nile, that like to disperse their roots into areas where we want to grow more docile annual bedding plants or vegetables. We might do it halfway, or more, around a shrubby plant during spring or summer if we plant on digging and moving it the following autumn. For most small and low profile plants, root pruning is sort of tolerable. The plants that we do it to may not like it, but it is sometimes necessary, and better than not doing so.
Trees are not like most small and low profile plants. Most are very sensitive to root pruning when mature. They are not so proficient at replacing the portions of their root systems that they are deprived of. Large roots that get severed are very susceptible to decay, which slowly migrates inward to the rest of the root system. Obviously, depriving trees of roots compromises stability to some extent. Because roots are below grade, it is impossible to know the extent of the damage caused by root pruning while it is being performed. This is a classic example.
The exposed freshly cut surface to the left in the picture above is not the stump of a small tree that was just cut down. Although it is, in this picture, a horizontally oriented cut surface of what seems to have been something that was standing vertically, it was actually cut vertically through a horizontally oriented root. Yes, that is it in the yellow oval to the right. It was cut because it was displacing the adjacent asphalt pavement, as demonstrated by the picture below. Rather that trouble us with this concern, the resident of the adjacent home cut the root of this mature photinia tree to protect his driveway from more damage.
The problem was that the major root that was severed was all that was supporting the tree. (The cut surface of the severed root is in the middle of the picture below.) The roots to the left and right of it may seem to be substantial in the picture below, but were mostly decayed stubs left from earlier root pruning. I was able to wrestle the stump out to dispose of it, without cutting more roots. The lack of other substantial roots is probably why the primary root was so big and expanding actively enough to displace the pavement.
The funny thing about all this is that I would have done the same thing. I would have determined that, although the tree would be very distressed by the loss of such a major root, it should not have been too terribly destabilized, and should have been likely to eventually recover. Even if it eventually succumbed to the distress, the loss of this mature but small tree would have been a better option relative to continued damage to the paved driveway. I certainly would not have expected it to simply fall over as it so comically did. The picture below shows what had been vertical trunks of the photinia tree that were quite horizontal after it fell over. The fractured asphalt pavement is visible at the far right edge. The top of the tree reached the center line in the adjacent roadway. I am sorry that I did not get a more amusing picture of it blocking the lane. I was in too much of a rush to clear the roadway at the time. This was something that I really was not expecting to encounter at work.
When a plant that should be compact or shrubby gets too lanky with exposed lower stems, it is described as ‘leggy’. We do not hear much about plants that develop ‘knees’. Perhaps that is because there is only one species that does so. That one species happens to be very rare here. If there are other specie that develop knees, I do not know what they are.
‘Knees’ are weird appendages that grow upward like stalagmites from the roots of bald cypress Taxodium distichum, particularly where the trees grow wild in swampy conditions. Knees can get quite tall. One of our professors used to tell us that they could do some serious damage to a canoe. Perhaps knees are why bald cypress is locally unpopular in landscapes.
However, I happened to notice that bald cypress is a common street tree in downtown Oklahoma City. Just like most other street trees, they are installed into small tree wells, but otherwise surrounded by pavement. They were remarkably healthy and well structured specimens that were too young to have damaged the pavement. Yet, I could not help but wonder what they will do as they mature. Even before the trunks grow as big around as the small tree wells that they are in, what would happen if knees develop?
There happens to be not one, but two bald cypress at work. The smaller is alongside a small stream. The larger is adjacent to a lawn where the soil is seemingly dry on the surface, but quite soggy just below the surface. This larger specimen is already developing distended burls that seem to be rudimentary knees. Although there is no pavement to break, the tree happens to be shading a picnic area where knees, if they develop, would be quite an obtrusive problem.