Shortly after silver wattle finishes blooming up high, any of four species of broom begin blooming down low. Brooms and silver wattle often naturalize together. All bloom with the same delightfully brilliant yellow. The four brooms are French broom – Cytisus monspessulana, Scotch broom – Cytisus scoparius, Portuguese broom – Cytisus striatus and Spanish broom – Spartium junceum.
Sadly, none are desirable species. All are exotic weeds. They are only a topic for gardening because they are so aggressively invasive. Not only do they overwhelm and displace native species, but they also enhance soil nitrogen to promote the growth of other exotic weeds! They are unpalatable to deer, and are not bothered by insects or disease. Furthermore, brooms are combustible!
It is best to enjoy their cheery bloom from a distance, where they grow wild where they really should not. The various species tend to dominate distinct regions, with some degree of mingling. Big specimens can get eight feet tall, but do not live long as they are replaced by herds of seedlings. French broom is the only evergreen species; but any can defoliate in response to hot dry weather.
Naturalized Himalayan blackberry is detestably aggressive.
Every palm tree in local landscapes is exotic. Simply put, all palms are originally from somewhere else. The desert fan palm, the only palm that is native to California, came from isolated colonies in desert regions many miles away. In fact, most plants in common landscapes are exotic. Landscapes composed of Californian plants likely include some plants from other regions of California.
With few exceptions, exotic plants are not a problem. However, some of those few exceptions have become very serious problems. Himalayan blackberry, blue gum, silver wattle, pampas grass, giant reed and broom are some of the more notorious examples. They naturalized to become prolific and aggressively invasive weeds. Some are more common than natives in many situations.
Naturalized exotic plants such as these are problems for local ecosystems, even if they do not affect refined landscapes. They compete with native plant species for limited resources, space and pollinators. A lack of pathogens from their homelands can be a distinct advantage. They alter the lifestyles of some of the native fauna. Some enhance the combustibility of the forests they inhabit.
The justifications for importing exotic species are as varied as the species themselves are. It might have been for lumber, forage, fruit, or vegetable production. Giant reed might have arrived here as packing material for cargo from southern Asia. Nonetheless, most naturalized exotic species, including the most aggressively invasive, came here simply for home gardening and landscaping.
Realistically, of all the countless exotic species that came here during the past few centuries, very few naturalized. Fewer are now aggressively invasive. Some with potential to naturalize may not have yet been able to escape the urban situations they inhabit. The problem now is that there are so many more exotic species readily available from all over the World than there has ever been!
Online marketing facilitates procurement of exotic and potentially invasive plant species from other regions, with minimal regard to regulation of such commodities.
According to these maples, spring is right on time.
Seasons in the Santa Clara Valley are not very distinct. They are not much more distinct in the Santa Cruz Mountains above. Hot weather in summer does not last for more than a few days, and usually cools off somewhat at night. Winter is never very cold, with light snow rarely falling only on the tops of the highest peaks.
Some believe that summer is our only season, with a few days of ‘not summer’. I would say that it is more like springtime all the time, with a few warm days, a few cool days, and a few rainy days. In many ways, it is great for gardening. However, it can be limiting for species that prefer more warmth in summer, or a good chill in winter. It can also be rather boring.
The vast orchards that formerly occupied the Santa Clara Valley were fortunately satisfied with the mild climate here, and actually enjoyed it. They got just enough chill and just enough warmth, but just as importantly, they appreciated the aridity. Late rain and humidity can ruin the same sorts of fruits in other climates.
Even without much distinction between seasons, springtime in the Santa Clara Valley was spectacular before the orchards were exterminated. A long time ago, tourists came to see it like the fall color of New England. Many or most tourists witnessed it while the weather where they came from was more like late winter. Natives considered the timing to be right on schedule.
However, the schedule did not coincide with what we learned about seasons in kindergarten. We cut out colored leaves from construction paper in autumn, even though there was not much fall color. We cut out snowflakes from white paper in winter, even though most of us had never seen snow. By the time we started cutting out flowers, most spring bloom was already done.
Norway maples always seemed to know what time of year it was. Schwedler maple, which is a darkly bronzed cultivar of Norway maple, was a common street tree in the Santa Clara Valley back then, particularly in tract neighborhoods that were build in the middle of the 1950s. Some disliked how it stayed bare and seemed to be dead after other trees bloomed and foliated.
To some of us, the reddish new growth of the Schwedler maples was what let us know that it really was springtime. Of course, we were done with all our spring planting by then, as allowed by the local climates. Also, the bloomed out orchards were already foliating. The maples just let us know that winter was completely finished and would not be back for several months.
Five young feral Norway maples at work are doing that splendidly right now. They lack the bolder color of the Schwedler maples, but they make the same statement. The bloom of the flowering cherries is exquisite, but not as convincing as the foliation of the maples.
Apologies for the delay of posting something for noon as I typically do.
These are just two pictures of two species that were not interesting enough for my Six on Saturday post this morning. Now that it is past one as I write this, it will be scheduled to post at two, hence Two at Two.
Most of what we propagate or recycle here has some potential to be used in the landscapes. Sometimes, we salvage something just because it it too appealing to waste, even if there is no plan for what will be done with it later. For example, we now have five nicely canned but otherwise useless Norway maples, just because they needed to be removed from a landscape.
I canned the four specimens of unidentified Rhus in the picture above because I thought I knew what they are, and that I wanted to plant them somewhere. Now that I realize that I have no idea what they are, and that the one thing I know about them is that they are invasive, I really do not know what to do with them. For now, they will stay canned right here where they are.
The buckeye in the picture below were grown just because the huge seed were too compelling to discard. Although I know what species they are, I also know that they are not very popular. Actually, because they defoliate and seem to be dead through summer, they are rather unpopular. They will likely just get planted in a bare spot on the bank of Zayante Creek right outside.
That is part of the problem of enjoying our work a bit too much. We take horticulture a bit too seriously, and feel compelled to find homes for all the unwanted flora that we can salvage.
Since lauristinus, deodar cedar and a few other species are happy enough here to naturalize and proliferate a bit too much where we do not want them, they should be just as happy to perform where we do want them. That is how we justify reallocation of such resources. We do it with other species too, just to avoid wasting them, or just because they are easy to propagate.
Norway maples and birches got canned over winter too, but I did not get pictures.
1. cyclamen – was something I grew in high school as a perennial that went bare for the heat of summer. It saddens me that it is so expensive, but also so expendable as a cool season annual.
2. cyclamen – will get a second chance this year. They got replaced earlier because of mold, but both the white group above and this red group went out into a landscape where they can stay.
3. ivy geranium – pruning scraps got plugged as cuttings to eventually replace zonal geranium that were mistakenly planted into hanging baskets. (That is the Pet Rock in the background.)
4. zonal geranium – pruning scraps get plugged as cuttings also. As they hopefully subordinate to ivy geranium, those in the hanging baskets will get pruned back more until totally replaced.
5. pigsqueak – that needed to be removed from one spot got plugged into another. Leftovers that could not be accommodated there and then, got canned for another time and another place.
6. Boston ivy – could be a problem. We wanted only a few copies. Rather than plug just a few pruning scrap cuttings into just a few cans, I plugged a whole flat of a hundred. Most are rooting!
This is the link for Six on Saturday, for anyone else who would like to participate:
Because its common name is so unappealing, dead nettle is more commonly known by its Latin name, Lamium. or more specifically, Lamium maculata. It is a low and subdued plant with pastel pink, lavender or white blooms, and small deep green leaves. However, modern garden varieties have silvery variegated foliage that brightens shady spots. Some are yellowish green.
The herbaceous stems spread only one or two feet at first, but then root into the soil where they land, and continue to spread some more. The mounding growth can get about half a foot deep, or a bit deeper where it can pile up on other plants or rocks. After late spring or early summer bloom, deteriorating flower stems should be shorn back to enhance density of foliar growth below.
Stems that begin to spread a bit too far into areas where they are not wanted can be left long enough to develop roots through spring, and then pulled up and planted where they are wanted. Even before they spread that much, no one would miss a few rooted stems discretely taken from established plants to make copies. Plants in sunnier spots want richer soil and more water.
Up at high elevations and out in deserts, where sunlight is most intense, plants can actually get more exposure than they need. The bluish or grayish glaucous foliage of the Colorado blue spruce from the Rocky Mountains, and the century plant from the Sonoran Desert, is actually designed to reflect a bit of sunlight so that the foliage does not scald.
Plants from foggy coastal areas, and understory plants that naturally live below the canopies of larger trees, do the opposite. They are deep green to absorb as much sunlight as possible. This is why Monterey pine and Monterey cypress are the same shade of dark green; and why most ferns are such dark green. Only tree ferns that stand above lower plants are naturally light green.
This can make it difficult to brighten a dark spot in the garden, since most lightly colored foliage wants an abundance of sunlight. White or lightly colored flowers would theoretically work nicely, but generally are neither permanent nor abundant where shaded. Golden foliage, like that of golden elderberries, golden arborvitaes and golden junipers, is greener in the shade.
Variegated foliage is different. Even if the green parts of the foliage are greener where well exposed than where shaded, the variegated parts are always variegated. Some plants are variegated with white. A few are variegated with yellow. Those that tolerate shade can brighten shaded spots nicely, or at least add a bit of contrast to dark green.
Even if the big pastel flowers of variegated angel’s trumpets and variegated hydrangeas do not stand out as well as they would against deeper green foliage, the foliage provides its own contrast. A concern with hydrangeas, as well as variegated dogwoods, is that they are deciduous, so lack foliage through winter.
Variegated Pittosporum tobira and variegated euonymus have smaller evergreen leaves. Variegated ivies are nice ground covers. On a smaller scale, so is dead nettle. Euonymus, pittosporums and ivies will sometimes need to have more vigorous unvariegated stems pruned out before they overwhelm and replace variegated growth.
A bit of Boston ivy adds a bit of texture and color to the stone wall.
My rant for this week is that I was deprived of my rant. I went to a nearby landscape that had been trashed by the so-called ‘gardeners’ for many years, only to find some unexpected and major improvements. I do not know what happened. Although it will take some time for the landscape to recover from the prior damage, it is already starting to function as intended.
It is obvious that the landscape was very well designed. Although I know very little about design, I know what is horticulturally correct. The designer selected species that are very appropriate for every application, even though none were particularly trendy at the time. Those who were hired to maintain the landscape only interfered with its intended development.
I noticed several improvements, but got pictures of only two features that bothered me the most prior to this season.
Obviously, the landscape designer intended the trailing rosemary in the picture above to cascade over the stone retaining wall, not so much to obscure the appealing stonework, but to break up its expansiveness. Obviously, the Boston ivy was intended to climb up from below to do a bit more of the same, and provide a bit of color in autumn, without overwhelming the rosemary.
Until recently, the so-called ‘gardeners’ had shorn the Boston ivy into useless little globs at the base of the wall. If it crept onto the wall, they were sure to remove it just as it was starting to exhibit color for autumn. The rosemary was never allowed to hang over the edge, and typically got shorn just as it was beginning a bloom phase.
Now, the Boston ivy is allowed to climb the wall somewhat. I suspect that it will be partly removed through the year, just so that it can provide a bit of color by autumn, but without getting too overgrown. Also, the formerly shorn edge of the rosemary is beginning to take on a natural form, and will likely start to cascade through summer, hopefully with occasional thinning.
What bothered me even more than the glaringly bare wall was how this pair of flowering crabapples in the picture below got hacked back annually just as the flower buds were beginning to show the slightest bit of color. Seriously! Every little twig that could have bloomed was removed. The so-called ‘gardeners’ were weirdly punctual about this.
Well, the trees got pruned a bit earlier last winter. What I did not bother to notice earlier was that much of the unsightly stems that had been disfigured by what the so-called ‘gardeners’ did to them were pruned back to healthier growth, while much of the blooming stems were left intact to bloom now! All the damage can not be repaired in one season, but this a great start.
Someone is putting serious effort into renovating these flowering crabbaple trees.
They are more than just shrubbier and more colorful versions of the formerly stigmatized trailing African daisy. Modern African daisies are actually various hybrids of several other species. Extensive breeding complicated their lineages enough for them to be known by cultivar names rather than by species names. To one degree or another, most are probably related to Osteospermum ecklonis.
These fancier modern hybrids of African daisy grow as annuals in harsher climates. If planted just after the last frost date, they bloom splendidly for early spring, and continue to bloom sporadically through summer. If they grow and bloom a bit too well, they may like to be trimmed back to bloom some more. Locally, they persist through winter as short term perennials, to bloom as winter ends.
Bloom provides pastel hues of yellow, orange, pink, ruddy pink, lavender, purple or white. Early spring bloom is most profuse, particularly for fluffy plants that were not trimmed back over winter. The biggest sprawling plants should get trimmed back after bloom. Subsequent sporadic bloom, mixed with random profuse phases, is inhibited only by warm summer weather and cool winter weather.
African daisy wants full sun and regular watering. Mature plants get about two feet deep and broad. If pressed into the soil, outer stems can develop roots to grow as new plants, as the original dies.
Deadhead finished daffodils to conserve resources.
The need to deadhead so early in spring is one of the few minor consequences of spring bulbs. Long before it becomes necessary to deadhead zinnia, canna and rose, the first flowers to bloom as winter ends are already finished. Many are those of spring bulbs. Their lingering deteriorating bloom can be slightly unappealing. What is more of a concern, is that some will likely try to go to seed.
The process of producing unwanted seed consumes resources that could otherwise sustain more useful growth. However, for spring bulbs that have finished blooming, production of seed for a new generation is more important than their own survival. That is why it is helpful to deadhead bulbs and many other plants after bloom. If deprived of seed production, they divert resources elsewhere.
Deadheaded narcissus, daffodil, freesia, lily and tulip store more resources into new bulbs, which they generate to bloom next year. Snowdrop and grape hyacinth cultivars that get deadheaded are not likely to get overwhelmed by their own feral seedlings. (It is neither practical nor necessary to deadhead crocus or big naturalized colonies of snowflake, feral snowdrop or feral grape hyacinth.)
While it is important to deadhead most spring bulbs after bloom, it is also important to not remove deteriorating foliage prematurely. After all, the foliage produces the resources that are necessary to generate healthy new bulbs for next year. Such foliage starts to slowly deteriorate immediately after bloom, but may linger for many months. Bulbs will shed their foliage when they no longer need it.
Until then, bedding plants or low perennials can obscure deteriorating bulb foliage as it falls over. Trailing gazania and dwarf periwinkle work nicely for shorter bulbs. If they get shorn low for winter, trailing plumbago, common periwinkle and African daisy can work nicely for taller bulbs.
Tony Tomeo 