LIFE CYCLES
Why plants die
The long and short of a plant’s life
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For many of us, plants mostly exist on their own.
We enjoy them,
We groom them,
We gift them,
We praise them,
We sound them,
We enchant them,
We magistral them,
We utilize them,
We house them,
We venerate them,
We denigrate them,
We terminate them,
We harvest, pluck, snap, cut, boil,
bake, blanch, steam, fry, broil,
dehydrate, grill, pickle, brew, oil, and consume them.
But, we only occasionally think about their life cycles.
And even less, think about their mortality.
Some plants live ‘indefinitely’: Paeonia- Herbaceous Peonies, Hemerocallis-Daylily, Hosta, Helleborus, Populous tremuloides-Aspen, Pinus aristata-Bristlecone Pine, Sequoia-Redwoods, etc
Others are more fleeting in their life span.
Many common Aquilegia-Columbine commonly live about 2-5 years.
Podophyllum peltatum-Mayapple drop the oldest roots once they are about 9 years old.
Each iteration or main stem of a Cornus alternifolia-Pagoda Dogwood lives about 10-20 years. After all, they are NOT trees.
Each new rhizome growth tip on an Iris-Bearded Iris blooms only once, if at all. The oldest rhizome gives-up and decays in 3-5 years.
Some bulbs like Tulips bloom only once and must be replaced by a daughter bulb. While it commonly matures in 1 to 3 years into a blooming bulb, it may require years to do so if the conditions are not right.
Even though, we break out Annuals and Biennials and lump most everything else as perennial.
Some plants being sold as perennials last about 2-5 years.
Hybrid Delphinium, Hybrid Lupinus, Digitalis-Foxglove, Verbascum-Mullein, Rudbeckia hirta-Black-Eyed Susan, Polemonium-Jacob’s Ladder, Dianthus barbatus –Sweet William must reseed to give the allusion of being long lived perennials.
While it has been proposed to change the labeling of some of the shorter lived plants from perennial to something more understanding, the labeling is not going anywhere. Triennuals, Quadrennials are two of the proposed names.
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EDAPHIC CONDITIONS
A community of plants requiring specific soil conditions |
Soil Structure
Too much clay, too much sand, too much gravel, too much of this and certainly not enough of that, whatever ‘that’ may be, is the common vociferous chant of the gardener.
Since I reside on one of the moraines on the near west side of Madison, my soils are approximately 60% Sand, 30% Loam and 10% Clay. I seemingly could water forever and never get any pooling in my landscape. While I may ruminate on not being able to raise moisture loving plants, I am however content to raise plants, including numerous bulbous types, that enjoy my conditions.
Stop trying to change your landscape’s soil conditions.
Please grow the numerous wonderful plants that enjoy your landscape’s soil structure, thereby providing you with proud accomplishments.
pH: Acidity vs alkalinity.
Again, it seems the plants we desire to grow the most are those that require a pH not found in our own garden. We add more sulfur to increase acidity or lime to increase alkalinity. Modifying and then maintaining the pH of one’s soil is a continuous task. Modifying your soil’s pH will require years.
Also, remember that the water coming from your well or Greater Madison’s municipal water supply is often very alkaline, negating your efforts. Sensitive plants growing outside their pH comfort level are often stressed to the point of death.
Nutrition-Fertility
Plants react differently to different types of soil nutrition. Plants native to serpentine soils, or with high iron or manganese or extremely poor nutrient soils will have extreme difficulties surviving without their loved conditions. Excessive or poor nutrient levels may result in improper, excessive or poor growth. Certain nutrients are required for disease resistance, quality foliage and flower color, fragrance and hardiness.
Most of our clay/loam soils have very adequate phosphorus and potassium levels. Adding much more phosphorus and/or potassium is a waste of money and fertilizer. A slow release low phosphorus (0-3%) and potassium (0-3%) fertilizer with a quality source of slow release nitrogen and a good mix of micronutrients is the best for the landscape. Avoid using rapid release nitrogen fertilizers such as 10-10-10. We don’t need any more nitrates in our ground water and phosphorus in our aquatic systems.
More information may be found by clicking on PLGF on our home page.
Humus – Organic Matter
We all seem to have the desire to add more and more organic material to our gardens. Some plants enjoy near 100% organic conditions, thriving in pure leaf/twig litter. However, others prefer damp sand with minimal clay or humus. Some prefer humus atop boulders, providing them with perfect winter drainage. Others prefer to live in humus poor conditions between rocks and in crevices. Most Armeria, Dianthus, Primula, Sedum and others prefer raised rocky gardens bermed above the surrounding landscape. Humus is consumed by soil organisms and therefore needs to be constantly replenished. Mother Nature throws all of nature’s debris onto the soil, continuously replenishing it. Humus is mostly desirable; however, remember it has the capacity to hold moisture.
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Water Water Water
How much and how often, is the gardener’s dilemma |
Water excess
Yes, a plant can drown, especially when a new plant is placed into a compacted non-draining soil, the pit it’s planted in fills with water and remains saturated. The newly installed plant’s roots die of oxygen deprivation. Making the pit larger and filling it with gravel, humus or whatever, does not change the pit’s ability to drain. However, if you make it deep enough, to access the sand/gravel layer that under lays most of our area, you could have good drainage. This layer is commonly 4-6’ deep. Planting your new trees and shrubs a bit higher than the existing soil level/grade, allows the upper roots to have some life saving air.
Flooding is a different situation. If the plants are very well established, they may be able to tolerate flooding for various periods. Some plants are much more tolerate of flooding than others. Improper selection dooms those intolerant. The tolerant ones often flourish.
Watering your plants with artificially softened water is often fatal. Winter deicing salts should not be sodium based as these will outright kill plants. Often, salts slowly build in the soil, challenging a plant’s survival. Salt build-up in soils is a major problem is dry areas where irrigation is the norm. Over years, the soils actually become unsuitable for plant growth.
Drought - Terminal dehydration
A plant often deals with dehydration much better than with excess watering. While wilting of a broad leaf evergreen and a deciduous woody ornamental commonly results in the oldest leaves turning yellow or brown about 7-10 days after the wilt. A plant typically recovers from this wilt but may look a bit stressed until new growth pushes forth, potentially in the following season.
If excessive wilting occurs, the plant reaches the point of no return, and dies.
Planting moisture loving plants in desert-like conditionals seems illogical. However, it’s apparently given little thought in many installations of moisture loving Clethra-Summersweet, swamp dwelling Larix-larch and swamp loving Cornus – Redtwig Dogwood.
A moisture meter is a wise investment in instantly helping determine the soil’s moisture content.
http://landscapedesigns.bz/moisture_meter.html
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The Physical Environment
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SUN LIGHT to SHADE
Some plants enjoy it full, hot and for full days
Others enjoy only fleeting sunny moments
However, few of them grow well inside caves
Otherwise known as interior office compartments
It’s puzzling to see shade enjoying Hosta, Impatiens, and Begonia planted in dry soils in full hot sun conditions. I guess we demand they flourish where we want them to, giving little consideration for what they desire. Apparently, if they sunburn and look impoverished for most of the season, so be it. Some will survive but many just fade away.
Planting full sun loving plants in shady environments reduces their strength, deprives them of the light required for flowering, decreases their resistance to diseases and increases the potential for predation. While they may survive, they will most likely not flourish. Many will die.
Growing plants out-side their desired environments is a sure way to encourage failure.
Winter sunburn
Some plants are ill-adapted to tolerating the clear intense sunlight of our extremely low humidity winter days. The combination of these factors, not only changes the color of many Thuja-Arborvitae to a bronzy olive green, but may also ‘drain’ away the moisture and destroy the plants’ cellular structure. Some plants such as Chamaecyparis obtusa-Hinoki Cypress are wonderfully hardy in Madison; however they are intolerant of winter’s intense sunlight. Planting them on the north side of buildings or coniferous evergreens, allow them to flourish. The same applies to a number of break-leaved evergreens: Ilex-Holly, and Mahonia repens-Running Grapeholly.
Wind
Plants that enjoy the calm of a forest environment are shredded when planted in fully exposed windy sites. Their leaves and flowers damaged, many give up and die.
Plants that rely on winds to create strong tissue, flop, thatch, break off and lose their ability to perform when planted in calm conditions.
Wind is important for keeping the air moving around the leaves, stems, trunks and flowers.
Without this air movement, plants that rely on wind for pollination don’t reproduce properly. Without wind to dry the surfaces of the leaves and stems, diseases and pests flourish. Without the wind’s stimulation, strong supporting tissue is not properly produced, if at all. Without wind, many of our food crops would have significantly lower yields.
Wind is important to plant life.
Tornadoes and Hurricanes
Excessive winds are nature’s destruction at its worse. Damaging everything in the its path, these winds snap, topple and or simply rip plants out of the earth. While trees endure the full brunt of these winds, other plants are not immune. Shrubs and herbaceous perennials may be pruned back and allowed to flourish in the coming season. A snapped off or toppled tree’s fate is nearly always fatal.
Hail
Hail storms strip a tree, shred a crop of corn and flatten a Hosta garden of nearly every life giving leaf and tender shoot. Some plants may not recover at all, while others are permanently disfigured.
Lightning
The sight and force of lightning striking a tree is truly a sight to behold and a sound to be shaken by. Watching a tree being blown apart or blasted in to flames is disheartening.
Fire
One of the more frightening destructive forces is a wall of fire destroying much of the plant matter in its path. However, fire can be a rejuvenating force in a natural landscape. Some plants must have fire to prosper. If a fire is fleeting, trees may survive. If hot and slow, it kills nearly even thing above the earth level. Viewing Yellowstone, shortly after a major fire, I saw blackened dead trees amid a fresh green regenerating meadow -- poignantly beautiful.
Erosion or Burial
The rapid removal – erosion of the soil from a plant’s roots, allowing them to dehydrate, is often fatal. If the erosion is slow, the roots often have the capacity to remain attached, sometimes developing magnificent natural art. Having viewed the vegetation and soil being torn from the mountain sides in Ecuador and being cast into the valley below, is plant death on a catastrophic scale.
Freezing/Thawing
Most gardeners know of hardiness zones. These zones are based on the AVERAGE winter’s low temperature from a period of 7-20 years. It is NOT based on the record low temperature for the entire winter. However, a plant’s low temperature tolerance is much more complex. Flower buds are more sensitive to low temperatures than are foliar buds, one year old wood, two + year old wood and their roots. Roots and flower buds are commonly the most sensitive parts of a plant. Hydrangea quercifolia-Oakleaf Hydrangea selected from its warmer habitats are typically unable to over-winter its flower buds. They are unable to tolerate temperatures much below -10F. However, plants selected from their coldest natural habitats, their flower buds survive temperatures in the -20F range. Provenance is very important and should always be kept in mind when selecting plants for you landscape.
Rapid freezing and thawing commonly causes dehydration on sensitive plants such as broad leaf and coniferous evergreens. If it’s severe, death often results.
Heat stress
When temperatures go over 90F, relative humidity is low and winds are strong, plants suffer. If available, water is pulled up out of the soil as quickly as possible, but transpiration removes it from the plant faster than it is replaced. The parts of the leaves furthest from the water transport veins wilt to the point of no return. Within 3-10 days of the stress occurrence, browning necrosis appears on the top and/or edges of the leaves and stems, manifesting the damaged tissue.
Our temperate plants temporarily shut down some of their functions once the temperatures approach 90F and restart them once the temperatures cool down.
Just like humans, plants may die from excessive stress.
Hardening off – Spring awaking
Plants gradually go into dormancy, readying themselves for winter. If this process is shorted by a sudden and rapid deep freeze, plants may not be able to initiate or complete the process. Some plants harden off quicker than others. If a plant’s winterizing cycle is out of balance, damage or even death may occur.
Some plants tolerate longer freezing temperatures than others. The internal ‘clocks’ of some plants push them into growth while temperatures as still much too cold. These may leaf-out and or bloom too early, commonly being frozen, damaged or killed by late freezes. In the spring of 2008, many Taxus-Yews did not leaf out properly and then when they did, the lateral buds grew but the terminal buds were dead. Some Taxus just died.
Soil temperatures
Plants also have a wide range of soil temperature tolerances during the growing season. For example, some bulbous plants, such as Tulipa-Tulips, require high soil temperatures to ripen, complete their life cycles. Other plants, such as Clematis like their roots cool. It would be ill advised to plant Tulips and Clematis next to each other. Growing Clematis in hot soils often dooms them.
A plant’s soil temperature tolerances also holds true for the winter. When a USDA Zone 5 rating is given for a plant, this is only for air temperatures. It notes nothing about minimum soil temperatures. A plant’s tolerance to a 48” deep frost in Zone 5 is very different to a Zone 5 with minimal if any frozen soil. A few years ago, our soils froze to a depth of nearly 6’. When Spring arrived, it was very warm. However, the plants’ roots were still in a deep freeze. Some folks noticed how late everything was pushing growth. With still frozen earth wrapping around every root, of course emergence is going to be slow.
Cleaning up the garden in the Autumn and removing all of nature’s insulating plant debris, allows the frost to penetrate much deeper. The NOAA web site provides updates on the frost depth in various locations in our state. They also provide frost depth under pavement. It is very interesting how deep it is under pavement and various snow depths. Soil temperatures, as various depths, are also provided.
http://www.crh.noaa.gov/product.php?site=MKX&product=HYD&issuedby=MKX
A plant’s tolerance to the frost depth and winter soil temperatures goes a long way in forecasting a plant’s survivability.
I prefer to clean-up my garden in the Autumn as I have little time in the spring to do so as well as I have so many bulbs and other plants pushing forth, I would sure damage many of them by Spring trampling around the garden. For more information on Autumn clean-up and mulching, see http://www.landscapedesigns.bz/archives/V19-autumnmulch.htm
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Insect and other invertebrates aka BUGS
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Invertebrate pests cause a tremendous amount of damage to our crops and gardens. We battle them with nearly every imaginable mechanism: manual removal, water blasts, other predators, huge arsenals of chemical concoctions – from household chemicals (that we erroneously assume are not as toxic) to mass produced pesticides, lures, traps and anything else we think may reduce their populations.
We seem to forget many invertebrates are controlled by: Bats, Birds, Fish, Spiders, Centipedes, and a wide range of other creatures. However, when they get out of control, due to the demise of their predators, or moved/introduced into a predator free environment, their numbers often swell. The Emerald Ash Borer, Asian Long-Horned Beetle, Asian Ladybeetle, Mediterranean fruit fly, Viburnum Borer, Magnolia Scale, Hemlock Woolly Adelgid and other pests pillage and plunder plants, significantly injuring or outright killing them in the process.
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Animal-Vertebrate Predation |
Vertebrate consumption
Plants are the foundation of life on this planet for nearly every animal living on its surface. Without plants, humans would cease to exist. We directly and indirectly consume plants. Rabbits, Deer, Squirrels, Rodents, and a host of other creatures dine on the plants in our landscapes. Having eradicated most of the carnivores from our landscapes, the herbivores, rabbits, deer, squirrels and other rodents are over-whelming our environments. They are eradicating some plants while encouraging those they don’t like to eat. They, with our help, are changing the natural and garden landscape.
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Diseases |
Fungi & relatives
Higher plants have been battling root, stem, leaf, flower, fruit and seed fungal infections since they evolved. We don’t know how to cure, let alone what many of them even are, many fungal infections in plants, let alone those infecting humans. Countless energies have been spent in trying to combat fungal diseases in our food crops, with the investment fortunately spilling over into our gardens. Seasonal variations in the weather, nutrition, and other factors allow a plant to resist or succumb to infections. Spring 2009 was wet and cold. Many resistant plants were not able to resist foliar fungal infections and where subsequently disfigured for the entire season. Some plants simply died as their roots rotted from being too cold and wet.
Bacterial
Bacterial infections in plants cause similar problems as they do in humans. In plants, they are extremely difficult, if even possible, to control. Some die quickly and others gradually die branch by branch. Fire Blight, a very common bacterial infection, afflicts a very large number of different plants. Cherries, plums, apples, pears, peaches and crabapples appear to just collapse overnight. Large portions of a tree’s leafy being suddenly turns bright rust-orange-brown and hangs devoid of life may be the first indication that anything was amiss. By then, it’s too late, its life force wiped away -- dead. Treatments for bacterial infections are, at best, only marginally effective.
Virus etc
Plant viruses are much more common than gardeners realize. Tulip Breaking Virus caused the collapse of the 17th century Tulip Mania trade in the Netherlands. They didn’t know what the infection was, as viruses had not yet been discovered. The first virus, Tobacco Mosaic Virus, was discovered in 1898. In plants, they are yet incurable. Plant viruses disfigure, weaken & often kill the host plant. The best defense is to remove and destroy (don’t compost) the suspect plant AND its roots.
In humans, virologists are just beginning to understand some viruses, such as, AIDS/HIV, Rhinoviruses and influenza. Virologists have described over 5,000 viruses with the assumptive potential of a million more to be discovered. http://en.wikipedia.org/wiki/Virus
Pollution, air or soil contaminants
Air pollution and soil contaminant kill or disfigure numerous plants.
Lawn herbicides applied when temperatures are over those recommended (~84F), allows the herbicide to volatilize and drift into and onto your and your neighbor’s garden plants. I have seen the damage and death caused by this drift and volatilization time and time again. I shudder when seeing lawn herbicides being improperly sprayed or applied directly onto the landscape plants, out-right killing desirable plants. PLEASE read the directions first and then use herbicides carefully and properly.
Air pollution slowly kills plants. Plants ‘breathe’ in air and whatever is in it. Yes, some plants can actually clean the air of pollutants. Often, their leaves and other parts discolor or show marginal or patchy necrosis. While some plants are notoriously tolerant of pollution others simply fade away.
Soil contaminants span a wide gambit of chemicals. Soaps, detergents, bleach, oils, engine fuels, sodium chloride (table and deicing salts), antifreeze, excessive rapid release nitrogen, production chemicals, ammonias, salts, acids, lacquers, oil based paints, and so many others, they would fill volumes to write about them all. Avoid applying these and other seemingly innocuous products onto your landscapes. Dispose of them properly through Clean Sweep. http://www.danecountycleansweep.com/
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So, why do plants die? |
The reasons are numerous, even more numerous than you may have imagined.
Plants are represented by about a half millions species with even more genetic variations commonly referred to as cultivated varieties, cultivars.
Each species and cultivar is sensitive to their individual life giving and draining forces.
After all, humans are but one species on this planet and we all die from something.
Grow what your environment desires and grow it well. |
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originally published V23 Autmmn 2009
Steve Lesch, Landscape Designs, Inc. © 2009 |
