First Published 6/30/2005
Weed and Feed Follies

Over the years, I’ve dealt with many frantic gardening couples. One of the most common scenarios involves one half of the couple pointing the finger at the other about the misapplication of a chemical in the yard. When the right chemical goes in the wrong place, the consequences for your plants can be catastrophic.

Deadly Dinner

Weed and Feed, a popular gardening product marketed under several different brand names, can be quite useful when properly applied, but its name has caused some confusion. As a result, more than one gardener has thought, “Wow, the perfect product – not only will it feed my flowers, it’ll kill the weeds, too!” If only it were that simple.

Weed and Feed is a fertilizer combined with a herbicide such as 2, 4-D; it’s meant to be used only on lawns. Lawns – and grasses in general – have a different metabolism than broad-leaved plants such as annuals, perennials, trees and shrubs. 2, 4-D is a selective herbicide: that is, it will kill broadleaf weeds like dandelions and thistle while leaving grasses (and, unfortunately, the weed quackgrass fits into this category) unscathed. As the weed killer does its work, the fertilizer feeds the grass, encouraging vigorous growth.

But while the herbicide in Weed and Feed discriminates between grasses and broadleaf plants, it can’t discriminate between broadleaf weeds and broadleaf ornamentals, fruits and vegetables. When Weed and Feed is used in flowerbeds, virtually every plant – weeds, flowers, vegetables and all – will be either destroyed or, at the very least, severely damaged.

Once Weed and Feed is spread into a flowerbed, the damage to the flowers shows up very quickly. Bedding plants such as alyssum or marigolds and vegetables such as potatoes and tomatoes are extremely sensitive to 2, 4-D and will soon suffer severe injury. On a warm day, with the plants’ metabolism and growth rate accelerated, the 2, 4-D will be absorbed and plant injury sustained within hours.

Geraniums, salvia and many trees and shrubs aren’t quite as sensitive to low concentrations of 2, 4-D, but if you were to apply even a moderate rate of the herbicide to the foliage of these plants, you can expect rather severe damage.

Symptoms of 2, 4-D damage are always worst at the growing points of affected plants, because the herbicide is absorbed by the leaves and translocated (transported) through the plant’s vascular system to these growing points. Cupping and twisting of the new growth is often diagnostic of a misapplication of this herbicide. Eventually, if they received a high enough dose, the plants will wither and die.

The Only Cure

Unfortunately, little can be done to save plants that have been accidentally exposed to 2, 4-D. Applying water to the soil to wash away the herbicide, which might seem the logical solution at first glance is ineffective; in fact, if anything the water may speed up absorption of the herbicide into its stems and leaves.

The only real solution is time. 2, 4-D won’t harm the soil in the long term; in fact, there are several soil microorganisms that treat 2, 4-D as just another food source. Over the summer, provided the concentration of herbicide isn’t too high, these microorganisms will break the herbicide down completely into its component elements: carbon, nitrogen and chlorine. This may take three or four months, depending on soil composition, moisture and temperature, but once the herbicide has broken down, it’s safe to replant.

Read Before You Feed

Most of the misapplications of Weed and Feed that I’ve come across arise simply because the right product is used for the wrong purpose. And to be honest, it infuriates me that people’s gardens are ruined because a salesperson didn’t have the proper training to make the correct recommendation. I don’t fault these salespeople as much as I fault the companies that retail the product, who often fail to provide anything beyond the most rudimentary training.

Of course, part of the blame must be assigned to gardeners who fail to read the label before applying garden products. But then again, how many of us can honestly say that we’ve thoroughly read any set of instructions, whether they’re for the car, the fridge or the DVD player? Education – even in the form of something as simple as a label – can be the key to avoiding catastrophes large and small.

First Published 6/23/2005
Fertilizing with Lightning

If you sit around the coffee shops in small towns across the Prairies, you might overhear a farmer talking about how his crops really greened up after a heavy thunderstorm. The surprising thing is, he may well attribute the rich, emerald colour of his crops not to the rain, but to the lightning – and there is some merit to the claim. Lightning, strangely enough, does play a role in the nutrient enrichment of soils.

From Nitrogen to Nitrates

To understand lightning’s place in fertilizing Prairie soils, it’s necessary to understand a little bit about how roots absorb soil nutrients. One of the most important of these nutrients is nitrogen, and it becomes available to plants only after being subjected to a commonly heard, but generally misunderstood process known as nitrogen fixing.

Nitrogen is abundant in its gaseous form, which comprises nearly 80% of our atmosphere. That amounts to four trillion tons of freely available nitrogen, and yet, farmers and gardeners alike still pay good money for this nutrient to nourish their plants. The problem with the nitrogen in the air is that although it’s plentiful, it’s useless to plants as a gas. To do any good, it must be fixed. That is, gaseous nitrogen must first be converted into nitrogen compounds such as nitrate (comprised of one nitrogen atom and three oxygen atoms) or ammonium (one nitrogen atom and four hydrogen atoms) before plant roots are capable of absorbing and processing the nitrogen compounds into usable plant proteins. This conversion is accomplished by nitrogen-fixing soil microorganisms, which form associations with certain plants (most notably legumes such as peas, beans and clovers) to transform the atmospheric nitrogen found in the pore spaces of the soil into the various plant-usable nitrogen compounds.

Shock Treatment

Lightning is also a nitrogen fixer. The powerful electrical discharge can break nitrogen molecules into atoms that quickly bond to oxygen atoms, transforming (with the help of water) atmospheric nitrogen into plant usable nitrates almost instantaneously, as the bolt lights up the sky. The nitrates rain down into the soil and the plants get a free shot of instant fertilizer.

The nitrates created by lightning are identical to the nitrates found in some garden fertilizer formulations. It’s also interesting that lightning-created nitrogen compounds bear a greater resemblance to chemical fertilizers than they do to so-called organic fertilizers; organic fertilizers are large complexes of a variety of carbon, oxygen and nitrogen-based compounds, while lightning-generated compounds are more akin to 34-0-0, a once-common farm and garden fertilizer.

An Impractical Solution

In all fairness, however, lightning does not contribute a lot of nitrates to the soil in a typical year, perhaps only a couple of pounds per acre on average on the Prairies. But when you consider that lightning has been battering the Prairies for thousands of years, it does add up; millennia of summer thunderstorms are partly responsible for the rich soils we enjoy today. One theory suggests that prehistoric plants relied exclusively on so-called “cosmic” nitrogen – often created by lightning – until demand exceeded supply, and plants and nitrogen-fixing soil microorganisms evolved to the point where they enjoy a symbiotic relationship today.

So if you’ve already picked out a spot in your yard to anchor a lightning rod, you’ll definitely want to reconsider. Even if such a plan weren’t incredibly dangerous and foolhardy, the damage caused by the blast of lightning would far outweigh any potential benefit.

First Published 6/16/2005
Rhizoctonia

Bedding plants that stubbornly refuse to grow despite plenty of sunshine, lots of fertilizer and a consistent water supply cause gardeners a great deal of aggravation. We often search both high and low for the cause of the problem when the answer is really in the middle – the middle of the plant, that is. That’s where the stem touches the ground, and it’s also where one of the most pernicious diseases of the garden loves to reside. It’s a fungal disease called rhizoctonia.

Suffering Snapdragons

Several weeks ago, a fellow greenhouse grower dropped off some ailing snapdragons for me to examine. He was frustrated because one or two plants in every six-pack simply refused to grow. Aside from their short stature, the plants looked fine – but diagnosing mysterious plant problems not only requires a thorough examination of the plant itself, but its environment and the history of treatments provided.

These particular snapdragons were grown under an excellent fertilizer and water regime, under the correct lighting conditions. But the key clue to the cause of the problem lay in the rooting media mixture. I’m a firm believer in the use of soilless mixture, not just for what it contains, but what it doesn’t contain. Soilless mixtures not only provide a good, loose well-aerated media, but they are to a great extent, disease and insect free. The stunted snapdragons, however, appeared to be growing in garden soil, and garden soil typically contains a fairly wide selection of plant diseases. While many of these soil-borne diseases don’t pose as great a threat to mature plants, such as those growing in flowerbeds, younger plants, such as transplants, are quite vulnerable.

The Deadly Middle Ground

I pulled one of the snapdragon transplants out of the container for a closer inspection and the roots were nice and white, indicating that they were likely free of disease. Similarly, the leaves and stems were green and healthy. A closer inspection, however, revealed a band of reddish-brown, dead tissue on the plant stem right at soil level. The appearance of a brown region just above the soil surface pointed rather strongly to a disease called stem rot, which is caused by a genus of fungus called rhizoctonia.

Rhizoctonia is a common soil disease that girdles the stems of young plants right at or slightly below soil level. It can attack a wide range of flowers and vegetables, and even produces a “black scurf” on the surface of potato tubers. (As kids, my brother and I called it “the black stuff that you can’t wash off the potato.” The black scurf didn’t cause any major problems; it just dotted the surface of the tubers, making cleaning a grueling endeavor.)

The strange thing about rhizoctonia is that it often allows the roots to absorb water, keeping the plant alive for weeks. But it destroys the tissue that moves food from the leaves and stems to the roots. As a result, the plants become stunted, and the base of the stem becomes so weak that the plants eventually topple over and die.

Once plants get stem rot, nothing can be done. In this case, the only proper course of action is to replace the plants. This is why vigilance is important; by checking your transplants often, you’ll increase the probability that you’ll catch the problem early, and limit the disease to one or two plants, rather than losing a whole crop.

A Clean Sweep

The best way to prevent diseases like rhizoctonia from attacking your plants is to keep your soil clean. Never start your seedlings or transplants in garden soil; use high-quality soilless mixes. And keep your pots clean, too, especially if they’ve ever harboured diseased plants; you can use a solution of bleach to kill most of the disease organisms in your containers. Also, keep in mind that although mature, well-established bedding plants are less prone to stem rot than transplants, injuring the stems with a hoe or garden fork can create a tempting entry point for diseases.

Cleanliness may seem like an odd virtue to apply to gardening, considering that plants are grown in “dirt.” (I prefer to call it soil; dirt is what you track into the house on your boots.) But clean, healthy plants and clean soil can go a long way towards achieving a clean sweep in the healthy plant sweepstakes.

First Published 6/9/2005
Stepping Stone Plants

Stepping stones are all the rage in gardens today, replacing cold, linear slabs of concrete. And while the stones look great, there is the question of how to fill in the space between the stones; bare earth just doesn’t cut it for most people. Most stepping stone pathways need a little help from the garden to look their best, and that’s where groundcovers come in – or more specifically, a subclass of groundcovers called stepping stone plants.

Groundcover Lowdown

“Groundcover” is not a botanical classification, but a grouping invented by gardeners to describe any plants that have a low, spreading growth habit that forms a dense mass of foliage. A “stepping stone” plant is a groundcover that really hugs the ground and features foliage and flowers that are not too sharp or spiny for barefoot meandering.

Ideally, plants grown for pathways should be no taller than a few centimetres and they should be tolerant of dry, compacted soils; pathways are often trampled by foot traffic, and tend to be drier than the rest of the yard. (No one wants to walk on a soggy pathway, so paths typically get only the water nature provides.)

Stepping stone plants have evolved a variety of strategies to gain a competitive edge. First, by producing masses of tightly spaced leaves, they can block out competing seedlings by limiting physical space, moisture and sunlight; they create, in effect, a nearly impenetrable layer of vegetation. They also tend to be rather shallow-rooted, growing where oxygen is more plentiful.

Another trait that many stepping stone plants (and other groundcovers) have is the ability to root at each leaf node. As the low-growing groundcover plants radiate outward from their original transplant site, the stems elongate, produce a leaf bud, and the stem again lengthens from this point, producing another leaf node. Not only does this pattern repeat, giving groundcovers a reproductive advantage, but they also produce roots a the base of each node to absorb more nutrients and moisture. Each node is capable of producing an entirely new spreading groundcover.

The Plastic Plant

There are a surprising number of excellent groundcovers for the Prairies, ranging from common choices such as wooly thyme (Thymus pseudolanuginosus) and creeping Jenny (Lysimachia nummularia) to one less popular species that I love because of its surreal texture. It’s commonly called the plastic plant or Astroturf because it really does look like it’s made from plastic. The plant’s Latin name is Bolax gummifera, and it’s native to the Falkland Islands and the Patagonian regions of Argentina. The species name, gummifera, is a reference to the heavily waxed foliage that gives the plastic plant its name. That waxy foliage is an excellent adaptive mechanism for the plant; it seals in moisture in times of drought, helps protect the plant from pest and disease attack, and even sloughs off extra moisture during torrential rains. And it’s almost as durable as a real plastic plant would be in the garden.

Bolax grows no more than about one centimetre tall and has exceptionally dense, light green, plastic-textured foliage. It doesn’t spread quickly, but I love its waxy foliage and it certainly creates a great deal of interest in the garden. However, the plant is a little rough to the touch, so don’t put it directly in between your paving stones if you like to walk around barefoot; rather, grow it along the edges of your pathway and use a softer, mat-forming plant such as wooly thyme as your stepping stone plant if you’re looking for something that will caress your soles.

The Path to a Better Garden

Stepping stone plants are tolerant of extremes in weather, require very little fertilizer and maintenance, and look a heck of a lot nicer than concrete. If you’re looking for a way to beautify your yard, just follow the pathway these versatile groundcovers have laid down for you.

First Published 6/2/2005

Most of us are familiar with the basics of plant sexuality: bees (or other insects) spread pollen from flower to flower as they forage for food. The fertilized flower produces seeds, which grow into new plants. But not all plants follow this simple pattern; the plant genus Arisaema (also known as Jack in the Pulpit), in particular, definitely pursues an alternative lifestyle.

A Popular Perennial
The genus Arisaema consists of about 150 species, with an extraordinarily wide geographic range, extending from Africa through southeast and central Asia, the Himalayas and North America. A few species are hardy on the Prairies, provided they are in a woodland setting complete with rich, leafy soil and shade.

Arisaema has long fascinated gardeners, particularly perennial enthusiasts; personally, I think it’s the most fascinating of all the perennials I grow at the greenhouse. As the common name implies, the flower, with a bit of imagination, looks like a person standing in a church pulpit. Arisaemas are worth growing for their unusual flowers, but they are all the more interesting for their remarkable sex lives.

Alternative Life Cycles
Most plants are monoecious, producing male and female flowers on the same plant. However, there are many dioecious plants, plants that actually have separate genders, such as hops, holly and ash trees. Flowers that are, botanically speaking, “perfect” are in fact bisexual; that is, each flower contains both male and female structures within the same flower.

Gender Reassignment
Arisaemas on the other hand, are neither monoecious nor dioecious; they are paradioecious. They could be called the transsexuals of the garden, because they change their gender as the situation requires.

Young arisaemas (or older arisaemas that lack vigour for whatever reason) are generally male, while well-fed, strong adult plants are typically female or bisexual; in effect, as the plant matures, Jack in the Pulpit becomes Jill in the Pulpit.

But this isn’t the only sex change arisaema can undergo. It’s fairly common for an arisaema plant to switch to producing only male flowers after the female flowers bear fruit; doing so takes less energy, and allows the plant to regain some strength. Seed production requires a lot more plant resources than pollen production, so flip-flopping between genders ensures that an arisaema has enough energy to expend on seed production when resources are plentiful, yet conserve energy when such resources are lean.

Jack or Jill?
The idea of gender as an immutable, unchanging aspect of our identity is fairly firmly rooted in human society, and I guess it’s not surprising, since a sex change in humans provides no direct evolutionary benefit (though it may certainly benefit individuals who undergo the change). But in the botanical world, a little gender-bending can give certain plants a competitive edge. In nature, when it comes to survival nothing is sacred; gender is just another tool that can be manipulated to ensure the survival of the species.