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Get Perennials Ready For Winter

81212thumbDilemmas are common in gardening. Should summer vegetables that are still producing be removed so that winter vegetables can get started on time? What about replacing summer annuals that are still blooming with winter annuals, and then replacing winter annuals with summer annuals half a year later? Should tender perennials be regarded as annuals, or get a second chance?

Right now, some perennials are looking tired. Many will be going dormant for winter. Many do not get much down time, and will start to develop new growth faster than old growth deteriorates. Not many make their intentions obvious. Deciding how to work with them can be confusing at times. It might take a few years and a few mistakes to get familiar with the habits and lifestyles of some.

If cut back too early, hardy zonal geraniums will not regenerate much until the weather gets warmer at the end of winter. In the interim, they are more likely to be killed by frost without the protection provided by old growth However, some varieties start to grow in winter. If not cut back soon enough, new growth mingles with old, so that they are difficult to separate when they do get cut back.

It is best to observe what hardy geraniums are up to before deciding on when to prune. If they start to develop vigorous new growth down near the ground, the old growth should probably be cut down as far as the new growth. It is likely better to take a chance that they might be damaged by frost. Those that do not start to grow right away can enjoy the insulation of old foliage for a while.

Thoroughly deciduous perennials, like deciduous daylilies, dahlias and some ferns, can be groomed of their deteriorated old growth without risk that they will start to regenerate new growth prematurely. However, cutting back some specie of salvia might actually stimulate development of exposed and frost sensitive new growth. Perennials that get damaged by frost later In winter should not be groomed of damaged growth right away. The damaged material provides a bit of insulation for lower growth, particularly if new growth was stimulated by the damage.

Posted on by tonytomeo · 13 Comments

Being Cool Might Be Overrated

31218thumbThis really is the best climate for gardening. Even though summers are mild, there are not many plants that want for more warmth. Even though winters are mild, it gets just cool enough for many plants that require winter chilling. Yet, there are a few plants, particularly plants from tropical climates, that can be damaged by frost. The best way to protect such plants from frost is to not grow them.

Of course, this oversimplified technique would prevent the cultivation of familiar plants like banana, angel wing begonia and angel’s trumpet. In cooler regions, it might involve bougainvillea, philodendron and some types of citrus. Most of us would prefer to take some degree of risk to grow marginal plants. Some may get damaged by frost and then recover. Others may be killed by frost.

Potted plants can be moved to sheltered spots when threatened by frost. Some can be brought into the home or garage temporarily. For some, the simple shelter of a porch or a dense evergreen tree might be sufficient. Bougainvillea and other plants that do not like to be potted might prefer to be planted under the eaves against a warm south-facing wall. A bit of warmth radiates from walls at night.

During the coldest nights, some of the most sensitive plants that can not be moved to shelter may need shelter brought to them. Burlap, plastic, paper or any sort of sheeting that can be temporarily suspended on stakes above the foliage should be sufficient. Leaves that touch the sheeting can potentially get frozen. The sheeting should be removed during the day so that it does not get too warm in the sunlight.

Foliage that does get damaged by frost should not be pruned away immediately. It may be unsightly, but if left for later, it helps to insulate inner foliage and stems from subsequent damage from later frost. Besides, immediate pruning stimulates new growth that will be even more sensitive to frost than was the foliage and stems that had already been damaged.

Posted on by tonytomeo · 10 Comments

Arborists Are Very Specialized Horticulturists

81205thumbThe first storm of the year has a way of reminding us if our trees need attention. Whether then need to be worked on this year or not, we tend to notice how they blow in the wind, or if they are full of dead and deteriorating debris that falls into the garden or onto the roof. As deciduous trees defoliate, they are less likely to be damaged by wind, but their structural deficiencies become visible.
This is when some of us will contact arborists to inspect and perform necessary arboricultural procedures for trees that have grown to big for us to maintain. We do not want trees to be damaged by the wind. Nor do we want them dropping limbs or falling onto whatever is within their reach. Those that are biggest and most beyond our reach have the most potential to cause major damage.
Arborists are horticulturists who specialize in the horticulture of trees, which is known as arboriculture. They assess the healthy, stability and structural integrity of trees, then prescribe necessary corrective arboricultural procedures, and if necessary, prescribe the best time for such procedures. Most arborists work with a tree service that is equipped to perform the prescribed procedures.
Arborists who are certified by the International Society of Arboriculture, or ISA, have passed an examination of their arboricultural expertise, and maintain their credential by continued involvement with the educational seminars, classes and workshops of the ISA. More information about the ISA, local certified arborists and even arboriculture, can be found at the website http://www.isa-arbor.com.
As mentioned earlier, arboriculture is specialized horticulture of trees. It is not something that gardeners should be expected to perform; particularly mow, blow and go gardeners who are not even proficient with simple gardening. Many arborists can concur that unqualified gardeners sometimes kill trees, and cause much of the damage to trees that arborists must later correct. Besides, arboriculture is the sort of work that can be very dangerous to those who lack training, experience or the necessary equipment.

Posted on by tonytomeo · 2 Comments

Colorful Berries Linger Through Winter

51125thumbJust as many flowers attract pollinators with color, some types of fruit employ color to get the attention of birds and other animals. Just as many flowers reward their pollinators with nectar, fruit is its own reward to the animals that eat it. The only catch is that those who want the fruit must disperse the seed within. For both the hungry animals and the fruiting plants that lack mobility, it is a rather equitable arrangement.

Much of the fruit that uses this technique ripens in autumn, and linger through winter, when there is not much other fruit. It is available to migratory birds and animals that want to fatten up for winter. Unlike nuts and large seeds that get buried locally by squirrels, the tiny seeds of winter berries typically get eaten and ‘dispersed’ more remotely. Some actually need to be scarified by digestion before they will germinate.

Because they put as much effort into attracting vectors to disperse their seed as flowers put into attracting pollinators, fruit and berries can add significant color to the home garden. Oranges, mandarins, lemons, grapefruits and other citrus are quite colorful, even though they do not expect to be taken away by birds, To attract crows, persimmon fruits get as colorful for winter as their foliage was through autumn.

Firethorn (pyracantha) is probably the most colorful and profuse of the ornamental berries. Various specie and cultivars of cotoneaster produce similar berries, but not quite so prolifically. They are popular for their resiliency. Toyon, which is the native ‘California holly’ that Hollywood is named for, is a bit too finicky for irrigated and refined gardens, but can be quite colorful with berries in wild or casual landscapes.

Firethorn, cotoneaster and toyon, as well as English hawthorn, all produce similar ‘pomme’ fruits, which are actually more like tiny apples than real berries. They are so popular with the birds that they are not very messy; although the birds may be if they loiter. English hawthorn is a small deciduous tree, so yellows and defoliates as the bright red fruit ripens.

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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.

Posted on by tonytomeo · 23 Comments

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.

Posted on by tonytomeo · 8 Comments

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!

Posted on by tonytomeo · 4 Comments

Fall For Colors Of Fall

51111thumbMild winter weather on the West Coast limits the choices for autumn color. So many of the trees, shrubs, vines and perennials that get so colorful where autumn weather is cooler do not get so colorful here. Mild weather also allows so many more evergreen plants and plants that do not get colorful in autumn to thrive here than in harsher climates. Consequently, the tougher and more colorful plants are not so common.

Fortunately for those who appreciate autumn color, there are a few choices that do not mind mild weather. The three most reliable trees for autumn color are sweetgum (liquidambar), Chinese pistache and flowering pear. All three turn yellow, orange and red. Maidenhair tree (gingko) is just as reliable, and turns bright yellow, but lacks orange and red. (‘Saratoga’ gingko turns pale yellow.)

If the weather is right, fruitless mulberry, tulip tree, black walnut and the various poplars display clear yellow foliage. Eastern redbud can do the same, but is a small tree. Smoke tree and crape myrtle are large shrubbery or small trees that can get as colorful with yellow, orange and red as Chinese pistache does. Japanese maples have the potential to turn yellow or even orange, but more often turn dingy brown.

Grapevines and wisteria are vines that can be somewhat colorful if they hold their foliage long enough to get noticed. Boston ivy, which is actually more closely related to grapevines than to ivy, is the most colorful of the vines in autumn. Unfortunately, it can be too destructive to paint, wood and whatever else it grabs hold of to be practical for home gardens. It works nicely on indestructible concrete walls.

Heavenly bamboo, which seems to have appealing but distinct foliar color for every season, turns richer shades of reddish bronze through autumn. Some cultivars turn rich brown. Others become more purplish red or burgundy. Unlike other autumn foliage that sooner or later falls through winter, heavenly bamboo is evergreen, so hold its color until it get replaced by another color in spring. Unfortunately, there are not many other evergreens that turn color in such mild weather.

Posted on by tonytomeo · 2 Comments

Mulch Suits Autumn Quite Naturally

81114thumbIt is silly for us to think that we know more about gardening that the plants who live out in the garden full time. We can help them along by giving them a bit more of what they need to survive, such as water and fertilizer. We can prune them to help them concentrate their resources into bloom and fruit production. Through it all though, we really need to be observant of what they do naturally.

For example, we water many plants through dry summer and autumn weather because we know that they are naturally endemic to climates that provide a bit of rain throughout the year, and that they can get dry without it. We fertilize them when they are actively growing because we know that is when they want it. Most deciduous plants get pruned in winter because they are dormant then.

This time of year, deciduous plants are defoliating in a very obvious manner. Evergreen plants are more subtle about shedding some of their foliage. Defoliation and shedding happens this time of year because plants do not need so much foliage, if any, when there is not so much sunlight for foliage to exploit. The days are shorter, and the sun is at a lower angle, so sunlight is less direct.

There are other reasons why winter defoliation is sensible. It makes deciduous plants more aerodynamic, and less likely to be damaged or blown down than they would be if they kept their foliage for wintery winds to blow against. Likewise, when the weather gets frosty, defoliated deciduous plants leave little to get ruined. What does all this suggest for seasonal garden chores for autumn?

Mulch, which can be spread at any time, is particularly timely for autumn, because that is when the garden expects organic material from above. Just like fallen leaves would do in the wild, mulch settles in through rainy winter weather, and helps to retain moisture after the rain stops next spring. It inhibits weeds that will want to grow as soon as the rain starts, and insulates perennials that grow slower or go dormant when the weather gets cooler. Mulch helps an unnaturally cultivated garden do what it wants to do naturally.

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Straight And Narrow For Trees

30731thumbIn the wild, trees do just fine without any help from anyone else. They certainly are not stupid. Their roots disperse for adequate stability. Their trunks grow upward as limbs spread outward for adequate structural integrity. Trees only need help in landscape situations because they are expected to perform so unnaturally. From the very beginning, their trunks are bound and their roots are confined.

While they are growing in the nursery, trees are bound tightly to stakes to keep their trunks straight. Unfortunately, this binding inhibits natural development of trunk caliper. Since they can rely on stakes for support, trees do not waste resources on developing the strength of their own trunks. The various eucalypti are particularly sensitive, and can bend over to reach the ground when unbound.

Roots are confined to cans (pots) or boxes because that is how trees are grown in the nursery. Even in regions where trees are field grown, roots must be severed when trees get dug and moved. Many types of trees do not mind much, and are eager to disperse roots into a new landscape as soon as possible. However, oaks, pines and many others do not recover as efficiently from confinement.

Once in a new landscape, most trees need to be staked to recover from being staked and confined in the nursery. New sturdier stakes that extend below the confined root system into soil below should stabilize newly planted trees. This is particularly important for evergreen trees that will be blown more by wind than bare deciduous trees, and particularly because most trees get planted in autumn and winter.

These new stakes should be installed a few inches away from the tree trunks so that they can support the trunks loosely when the tightly binding nursery stakes gets removed. To prevent abrasion, new straps should be somewhat loose, and cross over between the trunks and stakes. A pair of opposing stakes, with straps supporting in opposing directions, is sturdier than a single stake. A few straps may be necessary.

The new crepe myrtle trees in the picture above remain  bound to the stakes that they were grown with in the nursery. Sturdier stakes that can support the trunk in a less constrictive manner have yet to be installed.