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Plants Are Particular About Exposure

1212121032One of the most important differences between plants and animals is that animals are ‘animated’, and plants are not. Aquatic plants might float about, and might even drift into more favorable situations. Vines and plants with creeping rhizomes can likewise relocate. Otherwise, most plants are confined to the same locations where they grew naturally, or where they were planted. They need to get it right from the beginning.

Most landscape plants that are commonly available in local nurseries are fortunately suited to local climates. A few tropical plants that prefer milder climates, as well as a few plants that prefer cooler winters, can be found; but most plants that prefer other climates are simply unavailable here. Yet, even within their preferred climates, the many diverse plants in our gardens are affected by many other environmental factors.

Exposure is nearly as important as climate is. Some plants need to be completely exposed, while some prefer shelter from heat, cold, wind or sunlight. It all depends on how they live in their natural environments. Some naturally live out in the open. Others live in dense forests, where they need to compete with other plants for sunlight. Even if we do not know where our plants come from, we should know what they require.

Japanese maples are understory trees that naturally grow in the partial shade of larger trees in mixed forests. Some types can do well in full sun exposure, but are likely get roasted by reflected glare, or dry wind. Lace-leaf Japanese maples are more sensitive to exposure, so prefer partial shade in the afternoon, and shelter from wind. However, too much shade compromises foliar color of the red and bronze leafed types.

Most cacti and some types of yucca are just the opposite. They naturally live out in deserts, without any significant competition. In home gardens, they will lean away from shade. Knowing what plants want helps to find the best exposures for them.

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Prune Maples and Birches Before Sugaring Season

71206thumbMost of us Californians are probably wondering what that means. Sugaring season is more familiar to horticultural enthusiasts in New England, Canada, and more recently, in Alaska. It is the time of year that sugary sap get harvested from maples, and in Alaska, from birches. Maple sap gets refined into maple syrup and sugar. Birch sap makes birch syrup and sugar, a recent fad up north.

Why is this important here? Well, maples and birches know what time of year it is. Their sugaring season is relatively brief here; and they do not produce as much sap as they do in cold climates. Nonetheless, their sap will eventually start to flow later in winter, just when we expect it least. By the time we will be pruning dormant fruit trees and roses, it will be too late for maples and birches.

Therefore, maples and birches should either be pruned as soon as practical after defoliation, or after refoliation later next spring or early summer. They tend to defoliate before their sap gets too pressurized. However, if opting or the autumn pruning schedule, it is advisable to prune off one small stem first and then wait a few minutes to see if it bleeds. If it does, pruning should be delayed.

Bleeding may not be as harmful as it would seem to be for mature trees, especially since birches and many of the maples do not need much pruning of viable stems. If they get infested with sooty mold, a few small bleeding wounds on a big birch tree are more unsightly than unhealthy. However, several bleeding wounds can be somewhat distressful, especially for young Japanese maples.

If opting for the spring pruning schedule, maples and birches should be allowed to refoliate first. Their first leaves should be fully developed. This might be difficult for those of us who believe in pruning during dormancy, but it is better than causing sap to bleed when the trees need it most. Pruning can be done during summer too, but summer pruning should not be aggressive enough to suddenly expose formerly shaded bark to direct sunlight. Otherwise, bark can scald. So once again, timing is everything.

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Improvise While Flowers Are Scarce

61123thumbMuch of the color in the garden through autumn and winter is provided by foliage. Some foliage turns color as the weather gets cooler. Some had been blue, gray, gold, red, bronze or variegated all year, and just happens to get noticed more now that there is not much other color provided by flowers. There are a few flowers that bloom now or even later in winter, but not nearly as many as there were in spring and summer.

Coral bark Japanese maple and red twig dogwood display colorful defoliated stems as the weather gets cooler. The colorful berries of firethorn (pyracantha), cotoneaster and toyon will ripen about the same time, providing bright red color until the birds get them. Otherwise, there might not seem to be much more to cut and bring into the home to substitute for cut flowers, and add to all the colorful foliage, twigs and berries.

Well, this is where things get less horticultural, and more creative. All those old flowers and flower stalks that should get pruned off, and maybe a few old leaves, might be good for more than compost. Blooms of hydrangea, Queen Anne’s lace and lavender can be cut just as they begin to deteriorate, and hung upside-down to dry. They lose much of their color, and shrivel somewhat, but are nice options to fresh flowers.

Old flower stalks of New Zealand flax and lily-of-the-Nile have striking form once plucked of tattered flower parts and seed capsules. New Zealand flax stalks are tall and straight. Lily-of-the-Nile stalks are like star-bursts on sticks. If the natural color lacks appeal, they can be spray painted! Seed capsules of red flowering gum (eucalyptus) dry in loose clusters with stems that are long enough to arrange like cut flowers.

Pine-cones, magnolia grenades (seedpods) and sweetgum maces (seedpods) that fall from their stems can be drilled, and attached to sticks. There are no substitutes for real flowers, but there are no limits to creative and even weird alternatives.

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Planting Cool Season Cover Crops

71129thumbTraditional horticultural technology that was so common in the orchards, that were likewise more common, was more practical than so much of what we do in our modern home gardens now. Orchardists got good insects to take out the bad insects. They got mulberry trees to distract hungry birds from maturing apricots and prunes. They even got weedy annuals to control other weeds.

Once it got established, mustard grew wild under many orchards. It self sowed so efficiently that it did not need to be sown. It grew fast, and shaded out other nastier weeds. Anyone who wanted to pick greens could take all they wanted without setting it back. It was sometimes tilled in early, or cut early and left on the surface as mulch, but was probably most often left to die back naturally.

Besides controlling weeds, the mustard improved the soil and kept it friable, both by dispersing roots through it, and also by decomposing into it. Other types of cover crops help limit erosion through winter, or improve soil fertility. All are very easy to plant and grow, and almost all get all the water they need from rain through winter. They only need to be cut and tilled when they are done.

Of course, they are all ‘done’ at different times. Orchard mustard that never gets cut or tilled is never really done. It just perpetuates itself. Cover crops in home gardens are done when we say they are done, before the space is needed for something else. Some should be cut before self sowing and becoming more a weed than a cover crop, whether or not the space is needed right away.

Cover crops get planted by simply broadcasting seed onto freshly tilled soil that will not be used for anything until next year. After seed is broadcast, the soil can be raked lightly to cover the seed. If it is not watered right away, the rain will take care of it. Fava beans, oats, barley, millet, clover and annual rye grass are some of the more familiar cover crops. Sesame and sorghum are rare.

Freeway iceplant and old varieties of common geranium (Pelargonium X hortorum) can function as prettier perennial cover crops. The iceplant can be cut from established colonies and plugged as short cuttings about four inches long. When geraniums get cut back, the pieces can likewise be processed into cuttings. Unlike annuals, these would get removed when their space is needed.

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Even Houseplants Can Appreciate Rain

P71116Everyone is from somewhere. Not everyone is fortunate enough to be from California. Most of the various plants in our gardens, even if grown locally, are descendants of plants that were collected from all over the world. Most houseplants are from tropical regions. They perform well as houseplants primarily because they tolerate the sort of partial shade that they would get as understory plants in dense tropical forests.

Along with this advantage of tolerance to shade, tropical houseplants come with other disadvantages, such as an intolerance to frost. So, they are able to live inside the home, but are unable to live very long outside where winters are cool. Even areas of Southern California that do not get frosty can get cool enough to make many tropical houseplants uncomfortable. Consequently, they are confined to their homes.

That might seem to be acceptable to those who not think like plants do. Really, do houseplants even want to go outside? Maybe not. However, shelter from frost and cool weather also shelters them from other weather, such as wind and rain. Without wind and rain, any dust that collects on the foliage stays there. Mealybug and scale insects can proliferate and produce sticky honeydew, which also will not rinse away.

This is why some of us like to occasionally put our houseplants in a cool shower to rinse them off. It eliminates much of the dust, and clears out the stomata (respiratory pores). It does not kill mealybug or scale, but sets them back a bit, and rinses off the honeydew. Showering is also a good way to soak and rinse toxins from the soil. Only African violets, gloxinias and a few plants with fuzzy foliage should not be showered.

The only thing that works better than showering is rain. (Remember that wet stuff that starts to fall from the sky this time of year?) Rain is gentler, lasts longer than a shower, and is located outside where the mess of wet houseplants is not so bothersome. The only disadvantages of rain are that it can be cold, and is often accompanied by wind. A slight breeze would help agitate dirty foliage and dislodge dust, but strong gusts can knock houseplants over, and damage large leaves that are not adapted to any wind. Plants should be sheltered from both wind and direct sun exposure that might happen if the plants are not brought in before clouds clear after the rain.

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Autumn Color That Proves It

71122thumbThere may not be a good time to talk about it this year. The late warmth really put a damper on some of the autumn foliar color. Some trees are dropping their leaves as soon as they start to turn color, leaving only fading green leaves in their canopies. Only the most reliable trees for autumn color, sweetgum, Chinese pistache, flowering pear and gingko, are trying to make up for lost color.

Now, just because these four trees happen to color well and reliably in autumn does not necessarily mean that they are the right trees for every application. No tree is perfect. Gingko comes close in regard to adaptability to a broad range of applications, but provides only bright yellow autumn color. Flowering pear can be an excellent tree in most regards, but it very susceptible to fire blight.

The other two eventually get too big for some applications. Chinese pistache gets broad with low branches, and old trees (that predate the selection of the standardized male cultivar) can be messy with tiny but profuse fruits. Mature sweetgum trees are notoriously messy with obnoxiously spiked mace-like fruits, and can develop serious and potentially hazardous structural deficiency.

There are certainly more trees and plants that can provide foliar color in autumn. These just happen to be four of the most reliable, and most brilliantly colored. Chinese tallow turns dark burgundy and almost purplish, but colors best in response to a sharp and sudden chill. Red oak turns a monochromatic brown like that of a paper bag, but of course, the color does not appeal to everyone.

Years ago, it was advisable to select flowering crabapples and flowering cherries while blooming in spring because that was the most accurate representation of their floral color. (Photographs were not what pictures are nowadays.) This is still good advice. For autumn color, it is probably better to observe trees around the neighborhood, and then identify those that are most appealing.

Once a few are identified, it is easier to research them to learn about their distinct characteristics, and to determine if they are appropriate for particular applications or situations. Some might be too big. Some might be too messy. Some are not as colorful as others. Persimmon has the added bonus of fruit. Crape myrtle blooms nicely in summer. It is better to know before planting them.

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Trees Do Not Like Chimneys

P71027There are many reasons why fireplaces and their chimneys are not such a safety concern like they were decades ago. Only a few modern homes are even equipped with them. Installation of a new fireplace is outlawed in many municipalities, even if a fireplace gets damaged by an earthquake, and should be replaced. Urban sprawl has replaced almost all of the orchards and woods that once supplied affordable fuel.

Most of the few fireplaces and wood stoves that still get used are safer because their chimneys are outfitted with spark arrestors. Also, most combustible cedar roofs have been replaced by non-combustible roofing material. Nonetheless, chimneys can sometimes get overwhelmed by potentially combustible vegetation. Trees, large shrubbery and vines might need to be pruned for adequate clearance from the heat.

Vines like ivy, Boston ivy and creeping fig are sometimes allowed to climb chimneys because they do not damage bricks as easily as they damage painted surfaces. However, they can easily grow over the top of a chimney. Aggressive vines generate significant volumes of vegetation, and can accumulate even more from nearby trees. Because they are directly over chimney exhaust, they ignite as soon as a fir is lit below.

Trees that reach over chimneys take a bit more time to burn because heat dissipates somewhat in the space between the top of the chimney and the higher vegetation. Cypress, pine, eucalyptus, cedar and big junipers are very combustible. If they get close enough, ungroomed palms and yuccas can be even worse! Deciduous trees are mostly defoliated, and less combustible while it Is cool enough to use a fireplace.

Regardless, all chimneys need adequate clearance from vegetation. Trees and vines that were allowed to get too close while fireplaces were unused through summer will need to be pruned back before the first fire is lit to take the chill out of cooling autumn weather. Debris that collects behind (upslope from) chimneys should also be removed. It can be combustible while dry, and once dampened by rain, it can cause rot.

This is also a good time to start cleaning eaves-troughs (gutters) and downspouts. Yes, it may need to be done more than once if enough deciduous foliage continues to fall through autumn. Debris is easiest to clean out while dry (before it needs to be cleaned out), but unfortunately becomes messier with rain.

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Plant Spring Bulbs In Autumn

71115thumbOf all the gardening chores, planting dormant bulbs is probably the least gratifying. All we do is dig a hole to the required depth and width, set a few unimpressively dormant bulbs with the correct orientation and spacing, and then fill the hole with the same soil that was removed from it. The process gets repeated until all the bulbs are planted. Soil amendment and fertilizer might be added.

There is nothing to show for our efforts. When finished, only bare soil remains. We might want to plants flowering annuals or a light duty ground cover over the bulbs, or we might just spread mulch. If soil amendment is needed, it should be mixed into the soil at the bottom of the planting holes. Fertilizer can get dispersed over the surface of the soil after planting. There really is not much to it.

Planting bulbs is also a chore that is easy to forget about until it is too late. If we do not see them in nurseries, we might not think about daffodil, narcissus, hyacinth, grape hyacinth, freesia, tulip, crocus, lily, anemone, ranunculus, iris or other spring bulbs until we see them blooming next spring. Yet, this is when their dormant bulbs, corms, rhizomes, tubers and tuberous roots get planted.

Many types of bulbs become available in nurseries at the same time, and can be planted as soon as they become available. It might be too early to plant those that are not yet available. Gladiola, dahlia, allium, calla and canna are summer bulbs that will become available later because they likely should get planted later, although calla and canna do not seem to care when they get planted.

Daffodil, narcissus and grape hyacinth are probably the most reliable spring bulbs for naturalizing. Bearded iris is likewise very reliable, but needs to be dug, split and groomed every few years. Freesia and crocus may not naturalize as reliably. Lily, tulip, anemone, ranunculus and hyacinth are spectacular in spring, but are unlikely to naturalize because they prefer more of a chill in winter.

Some bulbs can be phased in their first year. For example, if freesia flowers are expected to last about a week, a second group of bulbs can be planted about a week after the first. A third group can be planted about a week after the second, and so on for a few weeks until the planting season ends. As the first group finishes bloom in spring, the second group begins to bloom, and so on.

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Plants Grow Up So Fast

50429thumbShortly after germinating and producing their first few leaves, many seedlings start to produce foliage that is indistinguishable from the foliage that they will produce for the rest of their lives. Other plants might initially be outfitted with leaves that are smaller, thicker, or somehow slightly different from what will appear later. Then there are those that produce juvenile growth that is completely distinct from later adult growth.

There are many reasons for juvenile growth. It might be a competitive advantage for plants that live in dense forests. For others, it might deter grazing animals. Ivy actually has three phases, with juvenile ‘ground cover’ growth that creeps over the forest floor in search of a vertical support, adolescent ‘vine’ growth that climbs the support, and adult ‘tree’ growth that blooms and seeds when it gets to the top of the support.

Eucalyptus trees produce juvenile growth that is more pungently resinous than adult growth, in order to deter animals that would otherwise eat it. Adult growth develops when the main trunks have grown beyond reach of most of the threatening animals. Vigorous new growth that develops in response to breakage or pruning later in life is also outfitted with juvenile foliage so that koalas and other climbers leave it alone.

Avocado trees grown from seed produce no obvious juvenile growth, but without wasting their effort on blooming and fruiting, they grow very fast and lanky to compete with a dense forest canopy, whether real or imagined. For their first several years, they need to be pruned for structure and containment. They eventually produce adult branches, and start to bloom and produce fruit (although the fruit might be variable.)

Avocado trees obtained from nurseries are grafted so that they are genetically identical to a specific cultivar (for conformity of fruit), and so that they can start to produce right away. Their ‘scions’ (upper part of grafted trees) are obtained from adult growth of stock trees, so do not take several years to mature. The same technique works for citrus, which otherwise produce fruitless and wickedly thorny juvenile growth.

Sometimes, juvenile growth is preferred. Ivy gets pruned out of trees and off of walls to preserve the juvenile growth as an appealing and efficient ground cover plant, while also eliminating the potentially destructive climbing vines.51104

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Arborists Are Physicians For Trees

71108thumbBefore the storms of winter get here, it might be a good time to make arrangements to get some help for big trees that need it. Smaller trees that can be reached from the ground may not need anything that we can not do ourselves. It is the big trees that have grown beyond our reach that may need professional help if they have problems. They are unsafe for us DIY garden enthusiasts.

Once late autumn and winter weather patterns start, storms can break limbs and destabilize trees. Identifying problems and executing necessary remedies can limit such damages before they happens. Disproportionately heavy or structurally deficient limbs can be pruned to reduce weight and wind resistance. Obtrusive limbs can be pruned for clearance from roofs and anything else.

Trees are the most significant and influential features of our gardens. They shade and extend their limbs over our homes and gardens. Not only can they cause serious damage by dropping limbs or falling, but they can also change how our home and garden are affected by their shade. They are worthy of proper maintenance, even when it is necessary to procure the services of an arborist.

An arborist is a horticulturist who specializes in arboriculture, which is the horticulture of trees. Arborists are essentially tree physicians, who evaluate the health, stability and structural integrity of trees, and make recommendations for maintenance, or to repair problems. Most municipalities require an ISA Certified Arborist report in order to issue a permit to remove an unsalvageable tree.

The ISA is the International Society of Arboriculture. Certified Arborists have passed an examination of their arboricultural expertise, and maintain their credentials by continued involvement with ISA educational seminars, classes and workshops. More information about the International Society of Arboriculture and local certified arborists can be found at the website, www.isa-arbor.com.

Arboriculture is not the sort of thing that gardeners should be expected to perform. It is completely different from the sort of mowing, shearing and pruning that they do. Sadly, much of the damage that arborists find in trees was caused by improper arboricultural procedures. Arboriculture also has the potential to be very dangerous to someone who lacks adequate training and equipment.