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Invasive Weeds Waste No Time

Aggressively invasive exotic species become weeds.

With few exceptions, the most aggressively invasive weeds here are exotic. In other words, they are not native. They came from other regions where they were likely compliant participants of their respective ecosystems. At home, where they must compete with other members of their ecosystem, they may not be so aggressively invasive. Ecology is the opposite of a home field advantage.

Exotic species become invasive weeds in foreign ecosystems for a variety of reasons. For some, the climate is more favorable. Some grow and proliferate more freely without diseases, insects and animals that troubled them back home. There are also several that simply compete more aggressively for space and resources than native species are accustomed to. It is a jungle out there.

Most invasive exotic species are annuals. Many are biennials or perennials. Some are vines, shrubs or even trees. Most were imported intentionally, for a variety of reasons, and then naturalized. Forage and cover crops were some of the earliest of exotic species to become invasive. Other invasive species escaped from home gardens. Blue gum eucalyptus was imported for wood pulp.

Regardless of their origins or physiological forms, invasive species are weeds. They compete for the same resources that desirable plants use. They impede on the aesthetic appeal of gardens and landscapes. Some types of weeds become hazardously combustible. Even if not directly problematic, invasive weeds disperse seed that can be problematic nearby. Many disperse stolons.

Most weeds start early and grow fast to get ahead of their competition. They are more active at this time of year than at any other time. They are also vulnerable. While the soil remains damp from winter rain, they are relatively easy to pull intact. They have not yet dispersed seed for their subsequent generation. Later, they are likely to leave behind seed and bits of roots that can regenerate.

It is important to pull or grub out seedlings of unwanted shrubbery and trees, as annual weeds. They are likely to regenerate if merely cut.

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Start Young Trees Off Right

Recovery is difficult for abused trees.

Young trees are so impressionable. Too much water can damage their roots, or cause them to disperse too shallowly. Improper pruning can disfigure their branch structure, and ultimately compromise structural integrity. Improper staking to keep them stable can actually interfere with development of stabilizing roots, and interfere with trunk development.

Newly planted trees will of course want to be watered from spring to autumn for at least the first year, and more likely for a few years. Those that will eventually be less reliant on watering as they mature are actually the most demanding while young, because their confined roots are not yet adequately dispersed for self sufficiency. The problem is that too much water can keep lower soil too saturated for new roots to disperse into. This causes roots to instead disperse closer to the surface of the soil, which is not only unhealthy for the trees, but puts the roots closer to pavement, other plants and any other features that they can eventually damage as they grow.

Many young trees should be pruned as they grow to eliminate structural problems, and to instead promote good branch structure. The problem is that improper pruning can actually cause structural problems that will be with the victimized trees for the rest of their lives. Pruning should leave no stubs that will take longer to compartmentalize (heal), or that might produce vigorous but weakly attached new stems.

Stakes are unfortunately necessary to stabilize new trees. The problem is that the trees can become so reliant on stakes for support that they do not develop enough trunk strength to support their canopy without stakes. That is why trees should be tied loosely enough to their stakes to be able to move at least a little in a breeze. Nursery stakes (that trees are bound to for a straight trunk in the nursery) should be removed when sturdier stakes are added.

New trees are naturally a bit more distressed than mature trees that have settled into their environment. They are consequently more susceptible to disease and insect infestation.

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Spring Pruning Of Flowering Trees

Some plants prefer pruning after bloom.

Most major pruning happens while the plants that need it are dormant through winter. That is why it is known as ‘dormant pruning’. Such pruning would be so much more disruptive while plants are blooming, fruiting, foliating or growing. Pruning that happens during other seasons is not as aggressive as dormant pruning. Spring pruning, although practical for some plants, is relatively docile.

For deciduous fruit trees, dormant pruning is very important. It concentrates resources into fruit production, but also limits production to sustainable quantities. Otherwise, such fruit trees would be unable to support the weight of their own copious fruit. Spring pruning of such trees is simply too late. By that time, superfluous fruit has already consumed significant resources, only to be wasted.

Stone fruit trees and pome fruit trees are familiar examples of deciduous fruit trees that rely on dormant pruning. Stone fruits include peach, nectarine, apricot, plum and their relatives. Pome fruits are primarily apple and pear. Ironically though, their fruitless but flowering counterparts perform best with spring pruning instead. As similar as they all are, they have completely different priorities.

Flowering cherry trees bloom more spectacularly than fruiting cherry trees, but produce no fruit. Similarly, flowering crabapple trees bloom more colorfully than fruiting apple trees, but produce only tiny fruit. Neither must sustain production of significant fruit. Nor must they support the increasing weight of developing fruit. Prolific bloom is their primary function. Spring pruning accommodates.

Spring pruning allows flowering trees to first bloom as profusely as possible. Pruned out stems have already served their purpose. Because fruit production is not a concern, spring pruning is less severe than dormant pruning. Nonetheless, because dormant pruning is so practical for so many plants, spring pruning may seem impractical. It is tempting to prune dormant flowering trees now. Doing so harmlessly compromises bloom.

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Blossoms Bloom Sooner If Forced

Stems of tiny blossoms really impress.

Pussywillow is an odd cut flower. It is neither fragrant nor very colorful. It just gets cut and brought into the home because the distinctively fuzzy catkins are so interesting. They are appealing alone or mixed with other late winter flowers. The otherwise bares stems can get cut just as soon as the fuzz is beginning to become visible within the swelling buds. Bloom accelerates once the cut stems are brought into a warm home.

There are actually several other plants that can provide bare twigs that can be ‘forced’ into bloom in the home. ‘Forcing’ is simply the acceleration of bloom of such twigs by cutting them and bringing them from cool winter weather into warm interior ‘weather’. Flowering quince, flowering cherry and flowering (purple leaf) plum have likely finished bloom; but forsythia, hawthorn, flowering crabapple and many of the various fruit trees that have colorful bloom will be ready to be forced any time. Some daring people even force redbud, dogwood, witch hazel, lilac and star and saucer magnolias.

When the deciduous fruit trees that bloom well need to be pruned in winter, some people intentionally leave a few spare branches to be cut and forced later, just before bloom. These include almond, cherry, apricot, plum, prune, nectarine, peach, pear, apple and a few others. When stems get cut for forcing, they should be pruned out from the trees according to proper dormant pruning techniques, and can be trimmed up accordingly when brought into the home. Flowering (non-fruiting) trees should likewise be treated with respect when stems for forcing get pruned out.

Twigs to be forced should be cut just as the flowers are about to bloom, and preferably, as a few flowers are already blooming. They should be put in water immediately, and if possible, cut again with the cut ends submerged. Buds that will be submerged when the stems are fitted into a vase should be removed.

Once in a warm home, the rate of bloom will be accelerated, although everything blooms at a particular rate. Apple and pear bloom later than most, and can bloom slow enough to justify cutting stems while already blooming. As forced stems bloom, they can be quite messy, but the mess is probably worth it.

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Coppicing And Pollarding Annoy Arborists

Pollarding is a long term commitment.

Coppicing and pollarding are the most extreme of pruning techniques. They may also be among the oldest in some cultures. Yet, arborists are correct to condemn both as improper. Coppicing is the complete removal of all stems and trunks back to a stump. Pollarding is the removal of all stems back to main stems and trunks. Both procedures happen in winter, annually or every few years.

Both coppicing and pollarding stimulate vigorous and prolific cane growth during the next season. Lush foliage of such growth is useful as fodder. Foliage of pollarded mulberry is the primary food of silk worms. Canes are good kindling for the following winter. Thin canes of various species are useful for basketry. New foliage of pollarded eucalypti is useful for both essential oils and floristry.

Of course, few rely on modern urban gardens for fodder, kindling, eucalyptus oil, or basketry material.

Arborists disapprove of coppicing and pollarding because both techniques ruin trees. Many of such trees are too structurally compromised to support the weight of secondary growth after the first year. Consequently, they rely on annual coppicing or pollarding. Some trees will support their weight for a few years. Strangely though, many properly coppiced or pollarded trees live for centuries.

Coppiced trees generate from stumps of cut down trees. Ideally, they begin young. Grafted trees are less cooperative. They are likely to generate suckers below their graft unions. Pollarded trees get to develop their main trunks and limbs prior to their first pollarding procedure. The locations of the first pollarding cuts is very important. Subsequent pruning will be back to the same locations.

Distended ‘knuckles’ develop after repeated coppicing or pollarding back to the original pruning sites. Pruning must be flush to these knuckles. Stubs interfere with healing. Annual pruning leaves smaller wounds than less frequent pruning. Secondary growth should be able to overgrow wounds efficiently. Cutting below knuckles leaves wounds that may be too big to heal before they decay.

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Some Shrubs Are Better Trees

Sculptural trunks are worth showing off.

So many really nifty small trees never get an opportunity to perform to their best potential. Many function so well as shrubbery that there is no need to prune them into tree form. Many just get shorn down because that is the most obvious option.

There certainly is no problem with maintaining large shrubbery as shrubbery if that is the intended function. Oleander, photinia, privet, bottlebrush and various pittosporums are all excellent shrubbery, and except for oleander, can be shorn into hedges. Yet, any of them can alternatively be grown into small trees.

‘Standards’ are shrubs that are trained onto single staked trunks. Small shrubs trained as standards, such as boxwood, azalea and euryops, are really only shrubbery on a stick. The larger shrubs though, are more often trained onto trunks about six feet tall so that they can develop as small trees with single trunks.

However, they do not necessarily need single straight trunks. Many have naturally sculptural trunks that are worthy of display. They can be planted as shrubbery, and simply trained up on a few of the trunks that they are naturally equipped with. They only need lower growth pruned away as they mature, instead of getting pruned down.

Overgrown shrubbery that has become so obtrusive that it might otherwise need to be removed can often be salvaged by getting pruned up as small trees. For example, if a New Zealand tea tree or myoporum has gotten so wide at the base that it is awkward to work around, the basal growth can be pruned away so that only upper grown that has adequate clearance remains suspended on exposed trunks. The gnarly trunks within are often more appealing than the abused foliage that obscured them.

Japanese maple, crape myrtle, water gum (Tristania laurina) and various podocarpus really are small trees, but often get shorn instead of pruned properly by ‘mow, blow and go’ gardeners who do not know any better. Olive, coast live oak and saucer magnolia are substantial trees that often get shorn into shrubbery before they can grow beyond the reach of abusive gardeners.

Hollywood juniper as well as some of the other larger junipers naturally develop into sculptural small trees that are just as appealing with or without their lower growth. The gnarly foliated stems are just as sculptural as the trunks and stems within. If space allows, they can be left to grow somewhat wildly with only occasional pruning of superfluous stems.

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Summer Bulbs After Spring Bulbs

Summer bulbs start late in winter.

It was easy to bury spring bulbs so discourteously in shallow graves last autumn. None of them got proper funerals. Perhaps cool season annuals obscured their interment sites. No one needed to know they were there. It seemed like a perfect crime, until now. They are back like the undead. After all, they were not dead when interred. They were merely dormant, and likely plump and healthy.

Crocus, snowdrop, narcissus and some of the other related daffodil might already be blooming. Otherwise, their foliage is emerging above the soil. They do not necessarily wait for the soil to get warmer later in winter. Hyacinth and tulip will bloom a bit later. Delayed planting delays bloom, but only for the first season. Established spring bulbs from previous seasons will bloom as they like.

Spring bulbs, including corms, rhizomes, tubers and tuberous roots, prefer early interment for a reason. They appreciate a good chill through winter. Although most get refrigerated artificially prior to sale, they certainly do not mind a bit more chill. Besides, they also appreciate early root dispersion, even while still dormant. They prefer to bloom early, but unfortunately, also finish bloom early.

Summer bulbs are very different. They go into the garden later because they do not require chill. Furthermore, many types are sensitive to minor frost if they begin to grow too early in winter. Since they start growth later than spring bulbs, summer bulbs generally bloom later. However, some bloom for extensive seasons. A few summer bulbs bloom from early summer until frost in late autumn.

Dahlia, canna and old fashioned white calla are the more reliable of summer bulbs to plant now. Old fashioned white calla may be rare in nurseries. Smaller, more colorful, but less vigorous callas are more popular. Such summer bulbs are more sustainable than spring bulbs, and can perform for many years. Gladiolus and various lily are spectacular summer bulbs, but bloom once annually.

Incidentally, unlike the spring bulbs, most summer bulbs are actually corms, rhizomes, tubers or tuberous roots.

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Knowing When To Prune What

Flowering plum trees can be pruned later, after bloom.

Maybe the weather took the surprise out of camellias this year. It has been so warm and pleasant that such big and colorful flowers are almost expected. Even if crocuses and narcissus did not bloom much too early, they are likely finishing a bit early because of the warmth and minimal humidity. Daffodils are not far behind. Hopefully, lilies and tulips will not be too confused. Pansies, primroses, stock, Icelandpoppies, ornamental cabbages and kales actually seem to enjoy the odd weather.

It was such a rush to prune everything that needs to be pruned in winter! Roses are already being outfitted with new foliage. Plum trees are already blooming, and will be followed by apricots, cherries, peaches and the rest. It was actually easy to get carried away, and prune things that should not yet be pruned.

Many of the flowering trees that are related to fruiting trees seem like they should be pruned. However, the rules are different, since they do not need to support the weight of fruit. Pruning only compromises bloom. Flowering cherries, flowering (purple leaf) plums and shrubby flowering quinces should instead be pruned after bloom finishes, and only if necessary. As flowering crabapples finish bloom, minor pruning probably will be necessary.

Lilacs, forsythias and spireas should be pruned by ‘alternating canes’, which means that older canes get cut to the ground as they get replaced by new canes. If done just after bloom, new canes develop through the following summer, and will be ready to bloom the following spring.

Quite a few trees, shrubs and vines likewise want specialized treatment. Fat flower buds of deciduous magnolias make it obvious that pruning should be delayed. Azaleas should probably make their intentions to bloom more obvious. Hydrangeas can be groomed of deteriorated flowers and dead stems, but plump canes from last year will bloom this year. Maples, birches and elms will continue to bleed if pruned now, so should wait for summer.

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Pruning Roses During Winter Dormancy

Pruning now promotes better bloom later.

Contrary to what the pleasant weather suggests, it is still winter. Most plants are resisting the temptation to break dormancy prematurely. They must know that the days are still short, regardless of the weather. Most plants are surprisingly proficient with scheduling. Nonetheless, dormant pruning should happen sooner than later. This includes pruning roses. They have been ready for a while.

Technically, roses are ready for pruning as soon as they begin to defoliate. Also technically, rose pruning can be as late as the buds of the bare stems remain dormant. Later pruning is preferable in some regions where pruning wounds are susceptible to pathogens. Such delay is riskier here where mild weather can disrupt dormancy prematurely. Wounds are less vulnerable to pathogens.

Pruning roses is about as important as pruning deciduous fruit trees. Without adequate pruning, rose plants become too overgrown to perform properly. Crowded stems are unable to elongate as they should. Diseases and insects proliferate in congested foliage, and damage bloom. Specialized pruning concentrates resources into fewer but significantly more vigorous stems and flowers.

Although the technique may seem to be drastic, pruning roses is not very complicated. Hybrid tea, grandiflora and floribunda roses should retain only three to six of their most vigorous canes. The canes should be only about two feet tall, and cut just above a healthy bud. If possible, they should be canes that grew during the previous year, from bottom to top. Older canes should be removed.

Pruning roses of other classifications may be slightly different. Some types may retain more canes. Climbing types likely retain old canes for several years before replacement. Carpet roses and other ungrafted roses can be cut nearly to the ground, leaving no canes at all. Tree roses are like bush types, but on top of short trunks. New canes grow from their graft unions on top of the trunks.

Of course, potentially vigorous sucker growth that develops from below the graft union of any grafted rose must go.

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Maintenance Gardeners Often Need Help

Gardeners can rake leaves and mow lawns, but may not be qualified for some of the more specialized horticultural techniques.

Even some of the most avid of garden enthusiasts get some of the work in the garden done by maintenance gardeners. In many regards, even the common ‘mow-blow-&-go’ gardeners can be very helpful. As long as they are not expected to work with trees or shear anything (or everything), they can be remarkably efficient at the tedious and most demanding of tasks that are not much fun. For example, and as the job description implies, they can mow boring lawns and blow inert pavement. We can tend to our own meticulous chores, such as pruning roses and burying bulbs.

However, as professionals, gardeners must be as efficient with their time as possible, so rarely have the luxury of devoting the sort of attention to our gardens as those of us who enjoy gardening as a leisure activity. Consequently, they tend to be more generous with automated irrigation than they need to be. The immediate symptoms of insufficiency are more apparent than the symptoms of excess; so too much seems to be better than not enough. To make matters worse, the driest area of a lawn or bed is the limiting factor for automated irrigation, since everything else that gets watered along with the particular dry spot gets the same frequency and duration (volume) of irrigation.

At a time when many of us are already trying to use significantly less water, it is frustrating to notice any waste. In most gardens, lawn uses more water than everything else combined, but is also the part of the garden that many of us relinquish to maintenance gardeners who are not always there to notice waste. Regardless of any drought or water conservation, excessive irrigation is expensive and unhealthy to trees and many other plants.

Unfortunately, irrigation schedules can not be prescribed, but must be determined by direct experience with the lawn or landscape being irrigated. Even without rain, lawns and landscaped areas require less water through the (normally) cooler and shorter days of winter. The trick to rationing is to give the garden only as much as it needs to survive without allowing it to get too dry, which will undoubtedly cause some friction with any gardeners who may work with it.