First Published 4/29/2004
Choosing Soil Amendments

Social scientists have described a phenomenon called “the tyranny of choice.” Basically, having no choice is bad, but having too many choices can be just as troubling, since people often second-guess themselves, wondering if they should have chosen differently.

Gardeners face the tyranny of choice whenever they visit a well-stocked garden centre. With hundreds of plants, tools, seeds, and supplies to choose from, how can you be sure that you’ve made the right choice?

The only way to fight the tyranny of choice is to set some boundaries, to narrow the field. Choosing the right soil amendments provides a good template.

Amending Choices

Gardeners who wish to improve their soil with amendments have a bewildering range of choices, including hog manure, steer manure, sea soil, peat moss and seaweed, to name just a few.

In the old days, farmers and gardeners enriched the soil with whatever was available; often, cow manure was the only real choice. And the crops grew just fine.

But in the modern era, farms and factories produce vast amounts of waste, waste that is, in fact, a rich source of plant nutrients that can be used to enrich the soil. From farm animal manure, bark, leaves, fish and shrimp parts, this waste is a valuable resource for land reclamation and home gardens. But there’s an awful lot of it out there, and the list of choices continues to grow.

Narrowing the Field

The truth is, I’ve experimented with pretty much the full range of soil amendments, and I’ve discovered that most of them do a pretty good job of improving soil quality. Fortunately, there are some very practical ways of narrowing down the field of choices.

When choosing a soil amendment, ask yourself a few simple questions. First, is the bag durable? Cow manure that spills all over the trunk of your car or your driveway due to a split bag won’t do your garden any good, and it’s a pain to clean up.

How about the directions on the package? Do they tell you how much to apply? Spent mushroom compost, the product that remains after mushrooms have been harvested, is a good source of organic matter, but can severely burn plants if over-applied. The problem is that mushroom compost is often bought in bulk, so there are no application directions to be found. At the very least, there should be a contact phone number so that you can ask the seller for advice.

Is the product overly wet? Some composts contain a surprising amount of moisture. If you buy wet compost, not only are you paying for a bunch of water, but water-laden bags are difficult to lift. Getting a back injury while trying to add organic matter to your garden is no way to start off the season.

Is the product properly composted? This one may be difficult to check before purchase, but if you notice a sour smell when you open the bag, that’s a sure sign that the composting process was never finished. You can still use sour compost, but with extreme caution; cut back the application rate to avoid burning your plants. Also, improperly composted amendments may contain viable weed seeds, the last thing you want to be adding to your garden.

Finally, can the garden centre staff selling the amendment answer your questions about it? If not, do they know someone who can?

No Second Guesses

Every gardening season brings with it a wide range of bewildering choices. But if you ask the right people the right questions, you will reduce the possibilities to a manageable number, whether you’re buying compost or calendulas.

First Published 4/29/2004

Social scientists have described a phenomenon called “the tyranny of choice.” Basically, having no choice is bad, but having too many choices can be just as troubling, since people often second-guess themselves, wondering if they should have chosen differently.

Gardeners face the tyranny of choice whenever they visit a well-stocked garden centre. With hundreds of plants, tools, seeds, and supplies to choose from, how can you be sure that you’ve made the right choice?

The only way to fight the tyranny of choice is to set some boundaries, to narrow the field. Choosing the right soil amendments provides a good template.

Amending Choices
Gardeners who wish to improve their soil with amendments have a bewildering range of choices, including hog manure, steer manure, sea soil, peat moss and seaweed, to name just a few.

In the old days, farmers and gardeners enriched the soil with whatever was available; often, cow manure was the only real choice. And the crops grew just fine.

But in the modern era, farms and factories produce vast amounts of waste, waste that is, in fact, a rich source of plant nutrients that can be used to enrich the soil. From farm animal manure, bark, leaves, fish and shrimp parts, this waste is a valuable resource for land reclamation and home gardens. But there’s an awful lot of it out there, and the list of choices continues to grow.

Narrowing the Field/
The truth is, I’ve experimented with pretty much the full range of soil amendments, and I’ve discovered that most of them do a pretty good job of improving soil quality. Fortunately, there are some very practical ways of narrowing down the field of choices.

No Second Guesses
Every gardening season brings with it a wide range of bewildering choices. But if you ask the right people the right questions, you will reduce the possibilities to a manageable number, whether you’re buying compost or calendulas.

First Published 4/22/2004

Lime
Many Canadian gardeners have a bag or two of lime in the garage; it’s one of those staples that offers a simple way to fix acidic soil. But lime shouldn’t be used haphazardly; understanding how it works will help you get the most out of lime.

Lime Lore
The admonition to add lime to problem soils often comes from eastern Canada or the west coast, regions that typically have quite acidic soil, which is partly due to their higher average rainfall. The more rain, the more lime is leached from the soil, and thus the greater the soil acidity.

However, in some regions of the Prairies, especially in the south, soils tend to have high concentrations of lime already. Applying more lime to these soils is just a waste of time and money.

That’s not to say that lime is unnecessary in the Prairie provinces. The northern, forested regions of the Prairies can have rather acidic soil, due in part to acidic peat moss. Even the rich, black soil zone that arches through the central prairies (cities such as Edmonton, North Battleford and Winnipeg fall within this zone) can be a little too acidic.

Only an accurate soil test can determine if your soil really needs lime. If a test shows that your soil pH is less than about 6.5, a touch of lime will be beneficial. Keep in mind that acid-loving plants like blueberries, azaleas and rhododendrons love acid and hate lime, so avoid adding lime anywhere near these plants. On the other hand, in the greenhouse I add extra lime to the soil of alkaline-suited crops such as marigolds and geraniums.

Lime Basics
Lime, generally speaking, is a white or off-white material derived from limestone. It’s available in granular or powdered form, depending on how it’s processed. In gardens, lime is primarily used to raise the soil pH, making it more basic or alkaline, a process sometimes called “sweetening the soil.”

Sweet soil sounds pretty appealing, but the reality is that by far the greatest number of species of garden plants like a slightly acidic soil. Overapplication of lime drives the soil pH too high, resulting in plants that are unable to absorb valuable soil nutrients. As well, many soil microorganisms that are critical for converting organic materials such as manure into plant food have a difficult time functioning in soil with too much lime.

Lime Lines
Even if you determine that your garden needs lime, keep in mind that there are many lime-based products on the market, with crucial differences between them. The most common garden limes are dolomite and calcium carbonate. Both are safe and relatively easy to use, and both raise soil pH, but dolomitic lime also contains magnesium, an essential plant nutrient. If you like to make up your own potting soil that includes peat moss, which is acidic, you must add one of these limes to sweeten the soil.

There are also a couple of less desirable limes on the market, including calcium hydroxide, also known as hydrated lime, and calcium oxide, better known as quicklime. Both of these limes will raise soil pH, but they are very unpleasant to handle, and can burn skin and eyes. Once they’re in the soil they’re safe enough, but getting them in the ground can be an uncomfortable and potentially dangerous chore.

Both calcium hydroxide and calcium oxide are often very finely powdered and react very quickly in soils, so they raise soil pH much more rapidly than either dolomite or calcium carbonate. But because of the health risk, my advice is to avoid them entirely.

To apply lime, simply scatter it into the soil surface and work it in with a rototiller. Even finely-powdered limes can take several weeks to react in the soil, so don’t expect instant results!

Enjoying the Limelight
Before you decide to add any lime to your homemade potting soil or garden, always talk to a professional first to determine how much, if any, lime you need. As a gardener, you owe it to your plants to serve no lime before it is time.

First Published 4/15/2004
The Biophiles

Why do we prefer one type of landscape over another? The obvious answer would seem to be, at first glance, that it’s a matter of personal taste.

That’s what I thought, too, until I had the opportunity to listen to a lecture by Dr. E.O. Wilson, a two-time Pulitzer Prize winner from Harvard University who has been called “The Father of Sociobiology” and “The Father of Biodiversity.”

Dr. Wilson’s lecture revolved around the concept of biophilia, which, in a nutshell, is the innate affiliation that people seek with the natural world. He suggests that human beings across all cultures have specific preferences, based on thousands of years of evolution, that affect their landscaping preferences. Basically, people prefer landscapes that offer ready access to sources of food and water, adequate shelter, and vantage points that allow us to see but not be seen by wild game or sharp-toothed predators.

According to Dr. Wilson, studies have shown that given complete freedom to choose the setting of their homes or offices, human beings gravitate towards environments that combine three features: elevation, which provides an excellent vantage point to spot oncoming predators; open, savannah-like terrain with scattered trees or small clusters of trees, which provide hiding places or escape routes from non-climbing predators; and finally, close proximity to a lake or river, essential sources of food and drinking water. The expensive properties overlooking the North Saskatchewan River possess all of those qualities: elevation is obvious, as is the ready source of water, and the typical backyard – a vast expanse of lawn with a scattered tree or two – provides an artificial savannah.

Other desirable environmental elements include sheltered retreats where dwellings can be built, a solid barrier (such as a hill or cliff face) to the rear, a fruitful landscape to forage, and distant, scattered large animals. (Perhaps this is why animals play such a prominent role in garden statuary.) Highly divided leaves, such as those found on Japanese maples, are prized because they provide concealment from predators while still allowing cowering humans to peer out into hostile territory from a position of relative safety.

Of course, not everyone has the time, space and cash to create a landscape that incorporates all of these features; these days, economics trumps evolution. But I think it’s wise to keep our innate desires in mind when we plan our landscapes. Time and again, I hear from people who are fed up with, for example, the cavernous feel of a yard with too many gigantic spruce trees. Dr. Wilson would argue that these kinds of yards make us uncomfortable because of the fact that the dense mass of these huge trees blocks the ideal savannah-like view. The elements of landscapes that we cherish, according to Dr. Wilson, disappear as the spruces take over.

So are our landscaping preferences driven by our evolutionary history? Perhaps. But in the end, we’re still free to make our own choices; after all, while most of us would love to live at the top of a river valley, there are those who are just as happy to live in a basement suite or ground-floor condo, despite the lack of a supposedly perfect landscape.

And yet, the prices of lots overlooking the river valley aren’t likely to come down anytime soon. Evolution may not be all-powerful, but its influence is undeniable.

First Published 4/1/2004
The Sunburned Cactus

Would you believe…a sunburned cactus?

No, this isn’t an April fool’s prank. Even though a sunburned cactus sounds about as likely as a frostbitten polar bear, I can assure you that I saw one with my own eyes just a few days ago. Furthermore, it’s not even a rare condition.

A Burning Issue

Sunburned leaves occur for a couple of reasons. Either shade-loving plants are planted in direct sunlight, or sun-loving plants are grown in low light for a long time and then suddenly moved into full sun.

This is what happened with the cactus I saw last week. It had been living on a subsistence diet of window-filtered winter sun, just barely managing to absorb enough light to survive, and then, without warning, it was moved to full sun.

Like most other plants, cacti will try to adapt to low light levels by changing the structure of their leaves (or stems, in the case of cacti), which allows them to scrounge more effectively for whatever light they can find. If you could look beneath the surface of leaves adapted to full sun, you would find thick, densely-packed plant cells, lined up like sentinels. These cells (called palisade cells) regulate the flow of sunlight into the leaves, allowing in just enough energy to feed the plant without gorging it to the point of injury. Shade leaves are thinner and wider and don’t have this densely-packed layer of palisade cells, so full sun tends to run a little wild, penetrating deep into the leaves and acting a little like a bull in a china shop, running amok and destroying plant tissue.

Once leaves or stems have adapted to low light, they can’t instantaneously shift gears when exposed to higher light levels. They become overwhelmed by the intense sunlight, developing large, glazed patches of damaged tissue.

Sunburning of plants is quite common around the house and yard from early spring and well into summer. Seedlings that are grown to the transplant stage indoors and then suddenly placed outside on the deck to harden off (i.e., get used to the cooler outdoor temperatures) are often damaged by sunlight. Tomatoes moved from shade to sun seem to be the hardest hit, developing a gray sheen anywhere the leaves are exposed to direct sunlight. And this, even though tomatoes are sun-loving plants!

Also, plants grown in excessively shaded greenhouses or plants left in the garage for a couple of days often suffer the same fate. In fact, any plant suddenly moved from shade to sun runs the risk of being burned.

Twice Burned

A sudden transition from indoors to the outdoor garden isn’t the only way to sunburn a plant. Hedges such as cotoneaster can be burned during the summer if they are pruned back too harshly. The leaves in the middle of the hedge, which had adapted to shade thanks to the coverage provided by the outer leaves, suddenly find themselves completely exposed. They quickly become sunburned and often fall off shortly thereafter, leaving the hedge looking rather unsightly until new, sun-tolerant leaves can grow.

Sunshine Blues

Sunlight is the source of life for all living organisms on our world. But sunburned plants and red-skinned sunbathers alike are living testimony to the fact that gradual adaptation to rising light levels is the best way to avoid getting burned.