First Published 8/26/2004
A Fall Trio

It happens every year, right around this time. No matter how well you’ve taken care of your bedding plants, there are always a few that simply burn out and fade away by the time September rolls around. The plants are often lanky, and flowers are few and far between. The problem is that there’s still plenty of good bedding plant weather left in the late summer and fall, and it’s a shame to waste it. Fortunately, you can call upon three tough but beautiful plants – garden mums, pansies, and flowering cabbage – to extend the season.

A Tempting Trio

Garden mums, pansies, and flowering cabbage aren’t closely related plants, but they do share a couple of advantages: they all enjoy relatively cool temperatures, and they put on a great display.

Of the three, garden mums are the most cold sensitive; even so, they can still endure fairly hard frosts easily. With cool temperatures, the flowers will last for six weeks or more, well into the fall; I’ve seen garden mums look great until November during those years the weather held. And depending on the variety, fall mums can produce hundreds of blooms.

Pansies are remarkably frost tolerant; I planted mine in early April, and they were quickly hit with a late spring snow and frost, but they endured the adverse weather, popping up out of the snow completely unscathed. If you plant pansies in late August or early September, you’ll have about two months of colour in a typical year. (It makes you wonder why bullies tend to call those they perceive as wimps “pansies,” considering how tough pansies are, it’s really a compliment.)

Flowering cabbage and kale are just as tough as pansies, and they really deserve more attention from gardeners. I planted flowering cabbage this spring and it still puts on a terrific show of purple and mauve, deeply serrated leaves; it always attracts attention. (They are best planted en masse to get the biggest impact; I have eighteen growing together in a 1 m by 2 m bed, but you can easily put half or even a third of that number in the same spot and they’d still look good.) Flowering cabbage and kale are incredibly frost tolerant and will produce a glorious display of colour until the snow flies.

Self-Sufficient Sisterhood

Here’s a nice feature of all three plants: if you purchase large, mature plants, they don’t require any fertilizer. Just keep them watered and they’ll be fine. (Even this chore is less bothersome, since by the late summer and fall the hottest days have passed and the plants’ demand for water diminishes.)

Insect and disease problems are rare for all three plants, with the exception of cabbage worms, which attack flowering cabbage and kale. But if you plant in the late summer or early fall, the problem is minimized, since most of the cabbage butterflies, which lay the eggs that develop into the worms, have already died off. If one or two worms do show up, you can take care of them easily with insecticidal soap.

Finishing with a Flourish

The fall bedding plant season is like dessert after a great meal – your appetite is mostly satisfied, but it’s nice to have something sweet to finish it off.

First Published 8/19/2004
The Fantastic Fibonacci

When you stop to enjoy the beauty of flowers, mathematics is usually the last thing on your mind. But whether you’re gazing upon the gigantic seed head of a sunflower or the intriguing shape of a chrysanthemum bloom, mathematics played a huge role in creating the very beauty you admire. As a young boy, I remember my father explaining that math was about patterns, and as a result, everything in the universe could be boiled down to a series of mathematical formulae. At the time, I didn’t really understand what he meant, but the thought fascinated me.

The Fabulous Fibonacci

It was the Italian mathematician Fibonacci who, back in the 13th century, explained, mathematically, why plants arrange their seeds, leaves and flower petals in a specific pattern. For example, leaves work best when they capture lots of sunlight. If one leaf is directly above another, the top leaf gets plenty of sunlight, while the bottom leaf receives substantially less. So, if the leaves are arranged in a pattern that minimizes shading, the plant makes the most efficient use of the available sunlight.

The same applies to seed heads. Plants such as sunflowers, with their huge flower heads, have found the best way to pack their seeds into the finite space allotted by developing the seeds in the specific pattern Fibonacci identified.

Do the Math

But what is this incredible pattern? Without going into grueling detail, suffice it to say that the arrangement of plant structures is based on Fibonacci’s “golden ratio” or “golden section,” represented by the Greek letter phi. The golden ratio is .618 – not exactly enlightening unless you’re a mathematician, but, in essence, it means that most plants tend to grow in fixed-angle spirals or turns, starting from the centre and moving outward. So for every phi (.618) turn per leaf or seed, you get the best “packing” of plant material into a limited space. As a result, leaves capture more sunlight and channel rainfall in an optimal path that flows down the stem and straight to the roots, while flowers get the best possible exposure to pollinating insects.

If you look at a sunflower seed head, you can see that the first seed develops at the head’s centre; the next, a slight turn to the right; the next, another slight turn to the right, and a little further out from the centre, and so on. Eventually, what you get is two sets of spirals, one turning to the left, the other to the right. This arrangement packs hundreds of sunflower seeds into a relatively small area. If the seeds grew in straight rows, far fewer seeds would fit onto the head, reducing the plant’s reproductive advantage.

Next, imagine the stem of a sunflower. The leaves are also arranged in a spiral up and down the length of the stem, again following the golden ratio discovered by Fibonacci. Or pick up a pine cone; if you look at the underside, you’ll see that the scales of the cone spiral outward from the centre as well. The same is true of cauliflower florets, the skin of a pineapple, or the petals on a flower. If you head into your garden right now, you’ll start seeing this pattern everywhere!

Invisible Order

This golden ratio is not restricted to plants; you’ve probably seen it on various seashells. And it’s consciously and subconsciously used by architects and artists, showing up in everything from car design to fashion. If you’re of a philosophical bent, you may interpret the golden ratio as a sign of implicit order in the universe, part of life’s ongoing struggle against entropy.

Of course, nature doesn’t fit into a neat little box all the time; there are many plants that don’t quite follow the golden ratio. It’s not a law, but it certainly is the dominant pattern of plant growth.

So the next time you’re entranced by a certain plant, you may want to bring a calculator and ruler along to verify and explain the true nature of its beauty. As my father once told me, math is everywhere – and it’s as beautiful as any garden bloom.

First Published 8/12/2004
The Forms of Fungi

Our gardens are home to many forms of life, from the annuals, perennials and trees we treasure to the insects and small animals we often try to keep at bay. Occasionally, there are also some strange and downright bizarre visitors, with correspondingly strange names like “dog vomit slime mold” and “stinkhorn.” But while the names aren’t very appealing, these fungi and fungi-like organisms should provoke not fear and loathing, but at least a touch of curiosity and awe.

Special Delivery

Strange, fungi-like growths are most likely to emerge after warm summer rains, particularly if you have a yard with plenty of rich soil, compost, or mulch, so having some mushrooms or molds pop up in the garden doesn’t mean you’ve done something wrong. Still, gardeners often bring me samples of these reviled organisms, sealed in airtight bags, as if the fungi are dangerous aliens just itching to contaminate the entire yard.

Just a few days ago, I received a carefully packaged sample of stinkhorn mushrooms; they look like baby carrots, capped with a black head that resembles the ashen tip of a cigarette. When you get a whiff of stinkhorn’s pungent aroma, you immediately understand where the name came from – it smells indescribably awful.

Of course, the stinkhorn’s appalling scent is just another of nature’s ingenious survival mechanisms. The smell attracts flies, who think they’ve found a nice piece of rotting meat to snack on; once they land on the fungi and realize they’ve been fooled, they fly off, covered in the stinkhorn’s spores. The flies spread these spores far and wide, helping the fungi establish new colonies.

People get antsy about stinkhorn for two reasons: the smell, and the fear that there is something radically wrong with their mulch or compost. “This mulch is no good, there’s mushrooms growing in it!” is a refrain I’ve heard many times, but there’s really nothing to be alarmed about. Since mushrooms are saprophytes, meaning they feed exclusively on dead or decaying organic matter, the vast majority of mushroom species won’t damage healthy garden plants. (Indeed, they’re part of the composting process!) Besides, even if you were dead set on getting rid of the mushrooms, there is no effective treatment.

Looking for New Roots

You may have seen mushrooms emerging in your yard shortly after a tree has been removed. These mushrooms are the fruiting bodies of beneficial mycorrhizal fungi, the same organisms you’ll find sold in garden centres as a growth supplement. The removal of a tree stimulates the mycorrhizal fungi, which inhabit the tree’s roots, to grow up and out of the soil, forming mushrooms. These mushrooms then produce spores, which are carried aloft by the wind in search of more roots to colonize.

Beware the Blob

The “dog vomit” slime mold is a yellow, slimy blob that looks so much like dog vomit that I’m sure more than a few children have been unjustly yelled at for feeding the family dog too much junk. These slime molds are not true fungi; they lack cell walls, which makes it easier for the blob to slither around and gobble up the bacteria that are its staple food.

Believe it or not, one slime mold species, Fuligo septica, is gathered up and eaten like scrambled eggs in Mexico – but don’t take that as an endorsement. You should never eat any unidentified mushrooms or slime molds you discover in your yard. They may be harmless to your plants, but they’re not necessarily harmless to your digestive tract!

Strange Visitors

Aside from the notorious fairy ring mushrooms, the bane of lawns everywhere, any fungi that show up in your yard should be cause for curiosity, not concern. They don’t stick around for long, and their strange forms and scents can serve as great conversation pieces. (For example, the thread-like “roots,” properly termed mycelium, of the fungi called foxfire contain bioluminescent compounds that give off an eerie, otherworldly glow.) So the next time you spot something that looks like the Blob lurking in a corner of your yard, don’t be revolted; instead, try looking at this strange visitor in a new light.

First Published 8/6/2004
Flower Intensity

Northern gardeners are often envious of the plants others can grow in warmer zones. But as it turns out, those of us who garden in cooler climes have a clear advantage on one very significant front: our flowers are often brighter, longer-lasting, and more abundant than the same varieties grown in much warmer climes.

Down Ohio Way

I recently attended a greenhouse conference in Ohio, and I wasn’t surprised to hear several northern growers lamenting over the ability of Floridians and other southerners to grow a wide range of tropical and subtropical plants.

But it’s a two-way street. For every northern grower jealous over what southerners can grow, there are equal amounts of southerners jealous of our cooler climate. No matter where you live, your gardening choices are dictated by your climate. Throughout much of Canada, what we can plant and grow successfully revolves around our attempts to work with a short growing season with long days and relatively cool nights. Gardeners in the southern United States face a different challenge: they need to find plants that can tolerate an endless string of very hot days and just slightly cooler nights. Many of the most outstanding perennials and annuals simply burn out in the deep south, producing only a short-lived display of so-so colour.

In the north, we take for granted the extended, spectacular flower displays of the summer. On the Prairies, our typically bright, arid days and cool nights produce larger, more intensely-coloured flowers than the same varieties grown at more southerly latitudes.

But why would flowers grow larger and feature more intense colours than flowers of the same variety grown in a seemingly friendlier climate? It’s all a matter of degrees.

Most flower pigments develop and sustain flower colour best when average summer temperatures aren’t excessively hot. Hot days and very warm nights are beyond the ideal range for certain enzymes responsible for the development of rich flower pigments, and furthermore, very warm conditions often lead to a rapid breakdown of those pigments that do manage to develop, shortening the flower colour duration.

For example, the campanula ‘Birch Hybrid,’ when grown at 28 degrees C has nice, dark purple flower petals; those grown at 30 degrees C are a light mauve, and look washed out in comparison.

Flower size variation can be even more startling. This same variety of campanula, when grown at an average daily temperature of 18 degrees C, develop blooms triple the size of those grown at 30 degrees C! You’ve probably seen this in your own garden, when flowers that mature during very high temperatures seem abnormally small. One reason for this is that the plants grown under hotter conditions must burn extra energy at night for respiration, instead of storing that energy for more growth. (Of course, plants indigenous to tropical regions don’t have this problem.)

Flower size and colour aren’t the only factors affected by temperature. When summer temperatures are too hot, flowers can display some pretty strange abnormalities. Campanulas may switch from single to double flowers – an attractive-sounding change, to be sure, but in reality they just look distorted.

High temperatures can reduce flower shoot numbers, too. Rudbeckia and coreopsis suffer an 80% reduction in flower shoots if temperatures climb from the high teens to the high thirties.

Begging for Better Blooms

While in Ohio, I heard many northern gardeners longing to grow bananas and wild gingers. But I heard just as many southern gardeners yearning for delphinium, foxglove and pansies. As one of those envious southerners said, “Delphiniums in Florida? Sure, they might last a week.” I guess no matter where you garden, the flowers always seem a little brighter just beyond the horizon.