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Archive for the Janet’s Journal department

Watering Plants: You Can Leave a Hose to Water, But You Can’t Make it Think

June 28, 2012   •   1 Comment

Water is the crux of gardening. For a beautiful garden, spend some time sorting out your plants’ individual water needs and how water flows in your soil.

By Janet Macunovich  |  Photographs by Steven Nikkila

 The hazy, hot eye of summer is upon the garden. Reach for the hose, but use your head to make the most of your efforts!

Herbaceous plants – annuals, perennials, vegetables, etc., that have no wood to hold them up – are simply columns of fluids. Roughly 95 percent water, they stand because liquid pressure holds their cell walls taught. Remove much and they fold. Wilted plants might recover with watering, but damage is done during the wilt – from localized scarring of tissues and greater susceptibility to diseases that can enter through weakened tissue to the more general stunting that occurs because the plant was not able to photosynthesize while dehydrated.

One inch of water per week is the average rule, but all plants are not average. Be aware of your plants’ specific water requirements.

Photosynthesizing is the harnessing of solar energy to make food. Plants use sunlight to split water and carbon dioxide molecules in their leaf cells, then recombine those ions with pinches of mineral matter to make sugars, starches, cell thickeners, new cells and everything else they need. Sunlight is the fuel, but water is the main ingredient, lubricant, coolant and transportation device in these leafy factories. Water’s atoms become part of the product, but water also keeps all parts supple and cool enough to work and is the conveyer belt which brings ingredients together and moves finished products from leaf to stem and root. In brighter light and warmer air, the plant factory works faster and more water is needed to keep it running.

No wonder plants ask for water every time we turn around in summer. The best thing we can do in July is to make sure you are watering plants wisely, not by rote but using a variety of methods geared to specific plants, soil and weather.

Take the standard rule, to give plants one inch of water per week. Some of us set out rain gauges to measure rainfall, then turn on sprinklers as needed to top up to that one inch mark. Others read cumulative precipitation in newspaper weather charts and drag out hoses when rain doesn’t add up. Both are smart practices, better than setting an automatic system to run every day or two, rain or shine. Yet you can water even smarter.

Annual impatiens, evolved to thrive in rich leaf litter in jungles, have shallow roots. They thrive when watered lightly and frequently.

One inch per week is an average, but all plants aren’t average. Some need more because their leaves lose more water to evaporation, or when they’re ripening fruits, or if they were cut back and must fluff out all new foliage. Big, thin leaves may lose so much water through evaporation on a hot, sunny day that the roots can’t keep up even if a hose drips there constantly. As an example, look at a Ligularia wilted into a green puddle. Many Ligularia plants suffer from root rot in summer too, overwatered by a gardener who reaches for the hose every time the plant wilts. The soil becomes super saturated and airless. Roots can’t burn – oxidize – the starches relayed from the leaves, so they die of starvation and rot.

Some plants need less water than others on a hot or blustery day. Gray, furry or needle-like leaves are designed for minimal water loss. Hairs that make a leaf gray or furry form a layer around the leaf that prevents immediate evaporation or blow-drying of water vapor emerging from pores. The vapor is trapped and sheltered inside the fuzz where it can linger and do its job as a coolant. To grow a gray leaf plant like lamb’s ear (Stachys lanata) next to a wilter like Ligularia, water very carefully, feeling for moisture in the soil at the base of each plant before turning the hose on just one plant or the other.

The amount of water available to roots isn’t based solely on amount of water poured onto the soil – that inch we measure in a rain gauge or in a wide-mouth container set on the ground under a sprinkler. Whether an inch will mean there’s enough, too little or too much water for the roots varies with type of soil, drainage, air temperature and wind.

Bee balm (Monarda didyma) likes a constantly moist soil. If grown on the dry side or where it is very wet and very dry, its chances of developing powdery mildew are greater.

Sandy soil has large pores – spaces too big to hold water up against the pull of gravity. Water runs through sand more quickly than through the tiny pores in clay or loam. An inch of water applied all at once to sand may be gone in a day though in clay it would have lingered at root tips for a week or more. So sand often needs more than an inch of water per week, meted out by the quarter- or half-inch every few days. Sand’s ability to hold water can be improved by topping it with evaporation-suppressing mulch and mixing into it a generous layer of organic matter or pre-moistened water-absorbent polymers (sold as “Water Sorb,” “Soil Moist,” etc.). These materials can absorb and only gradually lose up to 100 times their own weight in water. Yet even fortified this way, a sandy soil will dry more quickly than clay.

Drainage is the movement of water and air through soil pores. Some soils drain quickly, others slowly. Often the drainage depends on the type of soil well below the surface, so even a sand may drain slowly enough that moss grows on its surface. The only sure way to know how long water lingers in a soil, and how soon life-giving air is also back in the soil after a drenching rain is to dig a hole three to four inches deep and touch the soil. What feels cool is damp, but aerated. What feels warm or hot is dry. Soil that actually wets the fingertip is still draining.

Doing touch tests can be revelatory.

Even within a city lot with homogenous soil, some spots will dry more quickly than others. South-facing slopes and elevated areas may be dry while soil a few feet away is still moist, since ground tipped to the sun is often warmer and elevated sites catch more breeze and lose more water to evaporation. Dry spots in lawn or garden often show in early spring as dead patches or where one group of plants is slow to emerge.

Lungwort (Pulmonaria species) grown with drought-tolerant bigleaf forget-me-not (Brunnera macrophylla) in the dry shade is more likely to develop mildew than if grown and watered equally with hosta that thrive in constantly moist, well-drained soil.

We’re also taught to water gardens less often but more deeply so soil is thoroughly wetted, and probably have been told that watering lightly is bad practice since it “brings roots to the surface.” It’s wrong to think of roots “coming to” anything, but even some of the most scholarly horticultural texts use this phrase that misleads gardeners. As Dr. Joe Vargas of Michigan State University once said in a lecture on watering turfgrass, “I’ve looked at a lot of roots very closely, even dissected them, and one thing I’ve never found is a brain. They don’t know where water is. They can’t sniff it out, either.”

Roots grow if the soil around them is moist enough to supply water and nutrients needed to fuel cell division. They don’t grow if soil around them is too dry. Roots in a dry pocket or dry layer will not move toward moisture.

One thing we learn once we know that roots can’t seek out moisture is that root balls of new plants need special attention. A peat-based root ball of a container-grown plant may dry out far more quickly than the garden loam or clay around it. Roots within the peat will simply stop growing. Until a new transplant’s roots have grown beyond the peat and into the garden soil, its root ball has to be checked separately for dryness even if the soil around it is wet.

Another corollary of “roots can’t go to water” is that although it may be best when sprinkling many flowers, trees and shrubs to water deeply so that the whole depth of the root mass is wetted, plants with shallower roots need frequent, light watering. Lawn roots shorten in summer heat so a daily application of 1/8 inch of water is better than a weekly watering that means days-long drought in the surface layers. Annual impatiens evolved in rich leaf litter in damp jungles, and have shallow roots, too. Water them often, but don’t waste water by applying enough to wet the deeper soil layers every time.

A gray leaf plant such as lamb’s ear (Stachys lanata) does well where it’s hotter and drier. It has a layer of hair on each leaf where water vapor coming out through the pores is trapped and protected.

Another thing we hear often is that we should water early in the day, not in the evening, so leaves can dry off before night and be less susceptible to disease. This makes sense, reducing the amount of time that fungus-prone leaves are covered in fungus-promoting films of water, but then how does Mother Nature get away with evening and nighttime watering? Thunderstorms and rain showers come when they will, yet the normal state of being for plants in the wild is one of good health – maybe a bit of fungus here and there, but life-threatening epidemics as seen in rose gardens are rare.

If water is applied deeply and occasionally to supplement rain – perhaps weekly or bi-weekly – time of day is not so critical as in an every-day automatic system. Occasional watering means occasional openings for fungus infection. Daily late-day watering increases the chances of fungus infection by a factor of seven or more.

For some plants, an increased chance of fungus infection may be offset by water’s cooling effect. As temperatures rise into the 90’s, many plants stop photosynthesizing because their root systems can’t supply enough water to keep that process running at the high speed engendered by high heat. Pores in the leaf close, shutting off the upward flow of water like a drain plug in reverse. Without water flow, photosynthesis can’t take place, and the plant can’t produce fresh sugars to fuel its life processes. It lives off its reserve starches until the air cools. Dr. Vargas’ ground-breaking studies of turf irrigation clearly show that watering during the hottest part of the day is best for lawns because it cools the air around the grass, allowing it to continue to photosynthesize.

Other plants are more susceptible to fungus when exposed to drought or alternating wet and dry. If bee balm (Monarda didyma) that thrives in constantly moist soil is kept dry, its chances of developing powdery mildew are greater. Likewise, lungwort (Pulmonaria species) grown with drought-tolerant bigleaf forget-me-not (Brunnera macrophylla) in the dry shade is more likely to develop mildew than if grown in a constantly moist, well-drained hosta bed.

How about all the hype for weeper hoses and trickle irrigation, to conserve water and keep the leaves from ever getting wet? Does it sound like the only good way to deliver water? With weeper hoses, we often see increased spider mite damage. Regular rinsing keeps mites in check. Roadside plants struggling with pore blockage and light reduction under a layer of grime become more susceptible to pests unless rinsed regularly.

If all this seems too much to keep straight, maybe you haven’t been watered well! Why not go sit in the shade, have a drink and think about it? You may see that only one or two of the situations I’ve described here apply to your garden. While the heat’s on and your plants need it the most, fine tune that watering system!

Janet Macunovich is a professional gardener and author of the books “Designing Your Gardens and Landscape” and “Caring for Perennials.” Read more from Janet on her website www.gardenatoz.com.

Filed Under: Janet’s Journal Tagged With: Janet Macunovich, Janet’s Journal, Watering

Cultivating Murphy’s Law

September 30, 2011   •   

My friend Curt grew up on a “hard scrabble” farm in Kentucky early in the last century, an inquisitive boy who enjoyed the company of older farmers who repaid the interest by teaching him many old and secret ways. Agricultural college and then a degree and career in engineering put a fine edge on all he’d learned. When he said to me one day late in his life, “Janet, I think I’ve figured it out,” I took my notebook from my pocket in anticipation of revelation. What he said, in proof of a key tenet of Murphology known as Groya’s Law, was “I have looked and studied all these years and now I know I am never going to have any good idea what’s going on in this garden!” by Janet Macunovich
Photographs by Steven Nikkila

30 years ago, writer Arthur Bloch presented us with Murphy’s Law and a collection of other undeniable ironies. I’m basically an optimist and an opportunist, even a follower of philosophies such as “open your mind and the universe will provide.” Yet I found myself smiling wryly and even agreeing with what Bloch assembled to advance that basic tenet, “If anything can go wrong, it will.”

Over the years bits from that book would come back to me as I gardened. Situations I encountered while digging, planting or designing would strike me as spin-offs from Murphy’s Law and I would think, “There should be Murphy’s Laws of Gardening.”

Once you embrace Corollary #2 of Murphy’s Law (Everything takes longer than you think it will) you know you should never have mulch dumped in front of the garage door unless you’re willing to park on the street for days and even weeks. Recently I reacquainted myself with Bloch’s collection, in Murphy’s Law: The 26th Anniversary Edition (Penguin Group, 2003). I saw that although I recognized the proofs of Murphy’s Law I’d been cultivating, many other dictums in that book were also well established in my gardens. It made me laugh—which is a good thing to do on a day when Murphy’s Law pops up in your garden.

Despite the aggravation they can cause, there’s much to be learned from Murphy’s Law situations. Here’s a redtwig dogwood we dug from the bed that had been first covered with rock and then, when that mulch became unsightly, buried under a second layer of plastic and rock. If I hadn’t seen it I wouldn’t have imagined what tenacity a shrub can have. This one was growing a whole new root system above its original root ball. The lower roots were atrophying, oxygen starved at the unnatural depth. The new roots were more lively, growing into the organic debris that had accumulated in the uppermost layer of rock. Here are some of those rules and observations from Bloch’s compilation, with examples of where I’ve found them lurking in the garden. Perhaps given these connections, you won’t feel frustrated or critical of yourself the next time you encounter such circumstances. You can shrug off the effects and join me in saying, “Ah well, there’s nothing to be done. It’s all Murphy’s Law!”

Murphy’s Law and its first three corollaries

The Law: If anything can go wrong, it will. Its first corollary: Nothing is as easy as it looks.

One busy spring, I agreed to re-do a condominium entrance bed. It seemed a straightforward job—remove a layer of misbegotten egg rock and plastic, improve the soil and then plant flowers.

Various earlier projects ran long, pushing this make-over into Memorial Day weekend. Hoping to finish the work yet still have a bit of holiday time, we arrived at dawn to begin.

Murphy got there first. We saw the proof after we removed two truckloads of rock and peeled back the underlying plastic. Lying there was Corollary #1 in the form of an additional layer of egg rock and plastic.

Which simultaneously proved Corollary #2: Everything takes longer than you think it will. This bed renovation was going to go way over estimate.

With elegant simplicity, the situation moved right along to Corollary #3: Whenever you set out to do something, something else must be done first. What that meant in this case was that because the landfill closed early on holiday weekends, anything dug after noon this day was going to remain in my truck to complicate the beginning of my next project.

One of the worst things man can do to a tree is to stack mulch against the trunk. Moisture build-up and fungus join forces to rot the bark and destroy first the bark and then the vital cambium layer, maiming or killing the tree. The effect is the same whether that tree is a sapling or a forest giant. So why do we do it? Because someone working in a public place did it and others followed suit!New solution—new problem

Sometimes proofs take longer to develop. Such was the case the first time I recognized the garden variety of Corollary #4: Every solution breeds new problems.

It began one fall when I decided to repel bulb-digging squirrels with predator urine. At the garden center I considered my choices—fox, coyote or bobcat urine. Knowing there was a fox that visited the target area regularly, it seemed unlikely the local squirrels would find fox scent repulsive. At the other end of the scale, bobcat urine seemed like overkill. Thus I bought and used the coyote product.

That night, strange warbling noises woke the owners of those urine-marked gardens. Through the window they saw the fox, pacing back and forth along the marked beds, keening and yodeling.

For years we watched squirrels like this dig and eat our bulbs. Yet what we did to solve that problem led to greater headaches, proving the statement: Every solution breeds new problems (Murphy’s Law Corollary #4).Curious about the fox’s behavior, I cracked my books and came across reports that foxes will not share territory with coyotes. No wonder our fox was upset. He thought a coyote had moved in.

The true level of upset wasn’t apparent until late the next summer. Then, I’d been dealing with two first-ever situations for that garden—a plague of voles and an influx of rabbits. As I baited a live trap for rabbit, I mused “Why now?”

An answer leapt full blown into my head, the sum of a year’s worth of not-seeing.

“Have you seen the fox at all this year?” I began asking everyone who watched that garden. As more voices tolled the negative, my conviction grew more firm: With that bulb-protecting coyote urine we had repelled our resident rodent- and rabbit-control agent.

Not nice to fool Mother Nature

I thought I’d learned all I needed to learn from this episode but another lesson remained. Slow to germinate but full of certainty, Corollary #5 of Murphy’s Law completed the picture: Mother Nature is a bitch.

Snider’s Law: Nothing can be done in one trip.When a new fox finally filled our vacancy several years later, we called all the neighbors to come see his tracks across a late spring snow. Maybe if we hadn’t shared the news the good feeling would have lasted longer. But just a few weeks later the reports began to add up. This new fox was one that preferred raiding garbage cans to earning an honest living nabbing voles and rabbits.

An assortment of other laws and their gardening proofs

Let’s see if you can smile too, about what goes wrong in your garden. Think about these other laws, precepts and axioms as they relate to garden snafus.

Leahy’s Law states: If something is done wrong often enough, it becomes right. This is the complete and only explanation for volcano mulching.

Sodd’s Second Law is: Sooner or later, the worst possible set of circumstances is bound to occur. Sodd grins “Gotcha!” when you find yourself volunteered to a committee to landscape the church front entry and the majority of the other volunteers have never grown anything except opinions. And when you learn the soil in the entry area is not only brick hard but full of buried wires and pipes. And the budget for plants is suitable only for seeds. And the pastor informs you that the Sunday School classes should be allowed to help in planting.

Those who know and heed the “Unspeakable Law” know that saying, “Aren’t those hawthorn berries gorgeous? I hope they last the winter!” is to invite a flock of cedar waxwings to descend and strip the tree the next day.Consider Commoner’s Law of Ecology: Nothing ever goes away. This is not just law but religion among members of the species Canada thistle, scouring rush and bindweed.

Help yourself by helping others recognize the Unspeakable Law: As soon as you mention something, if it’s good, it goes away. If it’s bad, it happens. Watch and listen for this before your next backyard party. Keep a gag at hand, ready for use when an uninitiated person looks out over your garden and unwittingly begins the charm that calls this law into play, “Oh, how pretty! People will love those tall blue flowers! I hope it doesn’t rain.”

At work one day measuring a property for design, I stumbled upon a haphazard jumble of pots in a shrub-choked ravine. These pots still contained potting soil, still sported tags bearing the names of desirable exotics, and in some cases still held plant remnants. Peering up toward the house through bramble branches I saw this pile was an easy sidearm toss away from the deck and recognized its existence as proof of Fahnstock’s rule for failure: If at first you don’t succeed, destroy all evidence that you tried.

Likewise, those in the know are ready to shush the person who looks at your perfectly matched and says, “Oh, those look great together. You’re so lucky you don’t have rabbits and groundhogs eating your asters like I do.” Irene’s Law is: There is no right way to do the wrong thing. It’s so simple that any transgressions can be dumbfounding. Such was the case when a man who had sold his house to my friend Sue returned the next year at “just the right time” to give her a pruning lesson. His intent: to be sure she knew the right way to prune the flowering dogwood to maintain its perfectly round lollipop figure.

Cooke’s Law (It is always hard to notice what isn’t there) is actually pretty handy: I’ve seen it employed when two parties have joint ownership of an overplanted landscape or crowded woodlot. One party embraces the premise “something has to go” while the other stands on vague principle in objection to any removals. If the party in favor of reduction recognizes the applicability of this law, he or she might look for an opportunity in the form of the other party’s next business trip or out-of-town retreat. Should tree cutters or landscapers come then, it may be months before the objector even notices any change.

Philo’s Law has comforted me when I find myself dealing with people who don’t “get it.” It is: To learn from your mistakes you must first realize that you are making mistakes. Most recently, it came to mind as I exchanged emails with a gardener who had asked, “What can I use to get rid of powdery mildew? I’ve lived here about twelve years. I spray the garden every week with an insecticide-fungicide-fertilizer mix, but I can’t seem to beat the mildew.”

Sidebar: Rainy day reading

  • Ready to solo as a lawyer of Murphology? On a day when it rains and you’re a bit of weary of plant catalogs, resurrect this magazine. Find your own examples of these last few laws in your garden, and smile.
  • Barber’s Rule: Anything worth doing is worth doing to excess.
  • Snider’s Law: Nothing can be done in one trip.
  • Ducharme’s Precept: Opportunity always knocks at the least opportune moment.
  • Jong’s Law: Advice is what we ask for when we already know the answer but wish we didn’t.
  • The Principle of Design Inertia: Any change looks terrible at first.
  • Beach’s Law: No two identical parts are alike.
  • Imbesi’s Law of the Conservation of Filth: In order for something to become clean, something else must become dirty.
  • Milliken’s Maxim: Insanity is doing the same thing the same way and expecting different results.
  • Melnick’s Law: If at first you do succeed, try not to look too astonished.
  • Groya’s Law of Epistemology: What we learn after we know it all is what counts.

Janet Macunovich is a professional gardener and author of “Designing Your Gardens and Landscape” and “Caring for Perennials.” Read more from Janet in her newsletter available by writing to WhatsComingUp@gmail.com.

Filed Under: Janet’s Journal

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