Propagation Of Perennials By Division

80718thumbAutumn is for more than planting. It is when most of the aggressive pruning gets stared. It might be the best time to work with compost and conditioning the soil. Bulbs get planted. Gutters get cleaned. Leaves get raked. Perennials get groomed. We might think of it as a time of slowing down after such a busy summer, but in many gardens, autumn is just as busy with seasonal chores.

Autumn is when many of the spring, and some of the early summer, blooming perennials get divided. That means that they get dug up, split into smaller parts, and then replanted. Because there will be more smaller plants after the process than there were bigger plants before the process, some should get planted over a larger area, in other parts of the landscape, or shared with friends.

Not all perennials need to be divided annually, and some may never need to be divided at all. Perennials that bloom in autumn or winter, such as Japanese anemone and bergenia, get divided in spring, since they will have plenty of time to recover from the process to bloom on schedule. Black-eyed Susan does not likely care if it gets crowded, but can get divided simply for propagation.

Lily-of-the-Nile should be divided if it gets too crowded to bloom well. Division allows more room for the individual shoots to grow and bloom as they should. However, because it takes a while for newly divided shoots to recover, they should only be divided every few years or so, and only if they happen to be getting crowded. African iris gets divided if overgrown plants are looking shabby.

It is not always necessary to dig entire plants. If dividing New Zealand flax just for propagation, it is easier to pry the desired number of side shoots from a mature clump, without digging the main part of the clump. Agave pups might be (very carefully) pried off of larger rosettes just to keep the main rosettes neat. Black-eyed Susan and other deciduous perennials get divided while bare.

Bad Root Pruning

P81118-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.P81118+

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.P81118++

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.P81118+++

Sweetgum Color

P81117KWe may not get much foliar color in autumn here, but we get enough. Sweetgums do not need much cool weather to color well. They would probably have colored better and held their foliage a bit better if the weather got cooler faster, but we can not complain about what we got. Most of the crape myrtles are still completely green. Cottonwoods are defoliating, but without much color. Maples are rare here. The three best trees for color in autumn here are sweetgum, pistache and flowering pear. Of these, we happen to have several sweetgums here.P81117K+
Sweetgum is not the sort of tree that I would recommend for home gardens. They are innately very likely to develop structural deficiency. By the time such problems are identified, they are difficult to correct without disfigurement. Aggressive roots are likely to displace pavement, and sometimes invade septic systems. Then there are all those nasty maces; those hard and prickly round seed pods that stick into lawns and make pavement dangerous to walk on. They are too abundant and heavy to rake away as easily as fallen leaves. There are not enough squirrels in the entire forest to take them all!P81117K++
In some of our unrefined forested landscapes, where maces and falling limbs can fall into the forest without damaging anything, and roots can not reach concrete pavement, sweetgums can be allowed to go wild. (Unfortunately, most of ours happen to be near concrete within refined landscapes. That is another story.) Their tall and somewhat conical form happens to work very well with the native redwoods and Douglas firs, which provide the perfect rich green backdrop for their exquisite autumn color. Those of us who do not know better might mistake them for a native species. They look right at home here.P81117K+++

Six on Saturday: Fire Season

 

California really does have the same four seasons that the rest of America has. They just happen to be somewhat subdued in some of the milder climates. The rumor that California has only two seasons, summer and a few days of not-summer, is completely inaccurate. In fact, besides the traditional four season, we have a fifth season that overlaps at least summer and autumn. It reality, this season never ends. It is always ‘fire season’.

Like any other season, fire season affects how we garden here. We prefer to grow plants that are less combustible, which is often contrary to the preference for native specie. In suburban and rural areas, we must manage native vegetation and keep it away from our homes and other buildings. When the weather gets smoky from forest fires, some of us postpone gardening chores for healthier weather.

The Rincon Fire near Paradise Park (not to be confused with Paradise) burned for a few days a week and a half ago, and filled the Valley with thick smoke. By the time that smoke cleared out, smoke moved in from the Camp Fire that burned Paradise more than two hundred miles to the north. Smoke from the Woolsey Fire and the Hill Fire that both started on the same day in Los Angeles and Ventura Counties stayed to the south. The Bear Fire, which was the second relatively small forest fire in our region, started and was contained just yesterday, just a few miles outside of Boulder Creek. Most of us were not aware of it until after it was contained.

Incidentally, a 50% chance of rain is predicted for next Wednesday.

1. Clear blue sky finally appeared on Thursday morning.P81117

2. The orange moon demonstrates how smoky the sky was on the previous evening. It is not easy to zoom in and get a good picture of the moon.P81117+

3. Ponderosa pine forests are the more combustible parts of our region. The darker understory is a mix of coast live oak, canyon live oak, madrone and other chaparral flora. The dead ponderosa pine that I got a picture of for ‘Six on Saturday: Dia de los Muertos’ is to the right in this picture. Sunsets were spectacularly colorful before the smoke blew away. I can not explain why the color was so bland when this picture was taken.P81117++

4. Our debris pile continues to accumulate more biomass from the landscapes and surrounding forests. It is not yet big in this picture. It will get significantly bigger before it gets taken away. Once gone, we start the process all over again. It never ends. There is so much forest out there, and we are constantly trying to keep it away from the buildings.P81117+++

5. These numbers on the side of my work vehicle allowed the volunteer firefighter who used to drive it to go into areas that had been evacuated ahead of forest fires. Several of our vehicles are outfitted with these decals.P81117++++

6. This is the picture that you probably did not want to see. It is what remains of the home of one of my colleague’s clients in Malibu after the Woolsey Fire moved through. The front garden was exquisite. The home was even better.P81117+++++

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

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

Cape Honeysuckle

51118It may not bloom profusely, but cape honeysuckle, Tecoma capensis, blooms sporadically at random times throughout the year, and often while not much else is blooming. The bright reddish orange flowers contrast nicely against glossy evergreen foliage. Some blooms are slightly more reddish, while others are slightly more orangeish. A somewhat more compact cultivar blooms with light yellow flowers.

The long and limber stems of cape honeysuckle can not decide if they want to grow as vines or as shrubbery. They can be tied back and espaliered against a fence or trellis, or pruned and left to stand on their own. Large plants can get higher than the eaves. Overgrown thickets of stems can be cut down to the ground at the end of winter. They can regenerate and resume blooming before summer.

The narrow tubular flowers are about two inches long. They develop in terminal trusses, but only a few within a truss bloom at the same time. Shade inhibits bloom. Fertilizer seems to inhibit bloom by promoting vigorous vegetative growth. Fortunately, these vigorous shoots eventually bloom as vigorously as the grew. The four or five inch long leaves are pinnately compound, with five to seven small serrate leaflets.

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.

Horridculture – Bad Name

51104Junipers have a bad name. So do eucalypti. Too many of the wrong types were planted back at a time when they were too trendy. Those that were planted into inappropriate situations grew up to cause problems. The names of all junipers and eucalypti are now synonymous with those problems, even though there are many types of both genera that are quite practical for landscape purposes.
Get over it.
There are many junipers and eucalypti that are very good options for some landscape purposes. They need only minimal watering once established, and many will survive with none at all when mature. Some types of juniper grow as very low and very dense ground cover. With proper pruning, others can develop as exquisitely sculptural shrubbery or even small trees. (Just do NOT shear them!) Because of their very complaisant roots, some of the smaller eucalypti work very well as street trees.
I am certainly not promoting either junipers or eucalypti. They will not work for every application. I am merely saying that they should not be automatically dismissed because of their names. They were once overly popular for a variety of reasons, and those reasons are still valid.
However, I will say that there are a few species and varieties of each that are worth avoiding. They are likely what originally justified the bad reputations that are now shared by all of their relatives. For example, blue gum eucalyptus that was planted as a timber crop so long ago really is MUCH too big and messy for home gardens. Even where space is sufficient, there are probably better options.
Some of the current fads are also worth avoiding, or at least questioning. Some are very likely to earn a ‘bad name’ in the future, either because there will be too many of them, or because their faults will become evident as they mature. Because so many get planted within such a short time, many that mature at the about the same rate will develop their faults at about the same time.
For example, crape myrtle is such a useful and complaisant tree that it has been planted too commonly for just about every situation in which a tree is desired. It is resilient. It is complaisant with concrete. It blooms spectacularly. It colors splendidly in autumn. It really is an excellent small scale or medium tree for small garden spaces or near utility easements. It works very well in narrow park strips where larger trees would displace concrete. Yet, despite all the attributes, it is not good for everything, and does not get big enough to become a substantial shade tree, as it so commonly gets planted for. In the future, there will be so many crape myrtles in so many of the wrong situations that they will be considered to be too common.
Queen palm is another example. It used to be somewhat uncommon and respected. Through the 1990s, big box stores were selling them like junipers and eucalypti decades earlier. They happen to be very appealing palms that are more practical than the formerly more common Mexican fan pale, but have become so common that they were very often planted into situations that they are not appropriate for. Those that are under utility easements will need to be removed when their canopies start to encroach into utility cables. Because they are palms, they can not be pruned around the cables. Those that are able to mature will outgrow the reach of those who maintain their own gardens, or typical gardeners, necessitating attention from more expensive tree services. Like crape myrtles, they will also lose their appeal in the future.70222

Zinnia

81121The same cooling weather that is initiating fall color is what finishes the zinnias that bloomed so colorfully through summer. Like tomatoes, they can stay out in the garden until they succumb frost if they continue to perform, and if the space they occupy is not needed for something else. There should be no guilt with replacing them sooner. After all, they are technically warm season annuals.

Some of the more popular types of zinnias are identified as Zinnia elegans or Zinnia violacea. Most are known merely by their variety name. They have been bred so extensively than it is difficult to assign any of them to particular species. Most are susceptible to mildew if crowded or watered from above. They want full sun exposure and rich soil. Seed can be sown immediately after frost.

Zinnias are crazily variable. Some get more than three feet tall. Others are less than a foot tall. They can bloom in every color except blue. Some resemble other types of daisies, with distended centers. Others are as fluffy as African marigolds. Some bloom with small but profuse flowers. Others have fewer but bigger flowers that are wider than three inches. Most are excellent cut flowers.

Fall Color Is More Foliar

71122As zinnias, petunias, cosmos and other warm season annuals fade in the cooling weather, we might add a few chrysanthemums or marigolds for color through autumn, or we might go straight for pansies, violas or other cool season annuals that will provide color through winter. In the locally mild climate, there is always potential for some sort of colorful bloom. Mild weather has advantages.

It also has a few disadvantages. It is what limits the variety of apples that can be grown here. It limits the potential for bulbs that will naturalize. It is why we do not even bother with maple sugaring. Although mild autumn weather promotes colorful bloom of cool season annuals, and allows some of the warm season annuals to bloom right into winter, It subdues the color of deciduous foliage.

Sweetgum, Chinese pistache, flowering pear and ginkgo are the most reliable trees for autumn foliar color here, even in the mildest of autumns. Sweetgum and Chinese pistache exhibit the most impressive range of vibrant colors. Flowering pear can be comparable, and often displays deep burgundy red as well. Ginkgo exhibits only bright yellow, but it is probably the best of bright yellow.

There are a few more choices. Fruitless mulberry, tulip tree, black walnut and the poplars turn nice yellow if the weather is right, but they do not get quite as bright as ginkgo. If it gets cold enough, Chinese tallow turns rich purplish burgundy. Red oak turns a nice uniform brown. Most cultivars of crape myrtle can get as colorful as sweetgum, and also provide colorful bloom through summer.

Of course, it is very important to learn about the distinct personality of a particular tree before adding it to the garden. After all, no tree is perfect. Sweetgum eventually drops messy and prickly seed pods. Roots of both sweetgum and Chinese pistache can be aggressive with concrete. Flowering pear is susceptible to fire blight. Then there are a few trees that are colorful in autumn, that also have other benefits. Persimmon trees that are grown for their fruit turn the most fiery orange in autumn!

Big Trees Are Bad Houseplants

P81111By ‘big trees’, I don’t mean the various ficus trees that can grow up to the ceiling, and be quite happy inside. I am referring to the shade trees that live out in the yard, or forest trees that live beyond that. They are outside for a reason . . . or actually, several reasons. They are too big to bring inside. They probably would not like the climate inside. No one wants to rake fallen autumn leaves inside. Well, you get the point.
Unfortunately, on rare occasion, big trees that are outside end up partly inside by falling or dropping limbs onto the homes that they provide shade for. Just like trees seem to fall onto certain types of cars more than others ( tonytomeo.com/2018/11/04/trees-hate-cars ), trees seem to fall onto certain types of homes more than others. The difference between the homes that trees seem to dislike and the cars that they seem to dislike, is that there are actually reasons why some types of architecture is more susceptible to falling limbs or trees.
First of all, just as some trees seem to avoid falling on cars, some seem to avoid falling on houses.
Coastal redwoods in landscape situations are remarkably stable. In my entire career, I have inspected only three that have fallen. One had a massive pair of trunks that split apart and fell away from each other. Although they were on the fence line between two closely set urban homes, and there was almost no place for them to fall without destroying one home or another, they did the seemingly impossible. They literally fell onto the property line. One trunk fell out into the street. The other fell back into the backyards of the homes behind. The fence was pressed into the ground. The landscapes were seriously damaged. Gutters were stripped from both adjacent homes. Otherwise, there was NO structural damage to any of the homes. I am still amazed at how minimal the damage was!
The massive coast live oak two doors down from my former home in town was just as talented. It sprawled out over its associated home and the front yards of the two adjacent homes. It was so broad that I would not have believed that it could have fallen down without destroying one of the homes. Yet, it did exactly that . . . as I watched from my dining room. During a windy storm, it fell right toward me, and landed squarely in the front yard next door. It broke a few rafters on the edges of the eaves, and tore the gutters off, but that was the worst of the damage. It somehow found the best spot to fall where it would cause the least amount of damage.
Not all homes are so fortunate.
Victorian homes though, do not seem to be targeted by trees as much as others are. Most are closer to downtown, away from tall or very broad forest trees. Many are on somewhat narrow parcels that can not accommodate disproportionately large trees like the coast live oak in the picture above. Broadly sprawling trees tend to be too low to extend their limbs over the roofs of taller two story Victorian homes. Although taller than most other types of homes, two story Victorian homes do not occupy as much area as other homes, so are not such big targets.
Low profile homes of ranch architecture, or similar types of architecture, are more likely to be damaged by falling limbs or trees. Many happen to be located in suburban or rural areas, closer to bigger and broader forest trees. Their wider parcels can accommodate larger trees. Their roofs are low enough for trees to extend limbs over. Because they tend to be on a single level, they occupy more area, so are larger targets.