First Published 5/26/2005
Cerebral Celosia

Have you ever had the urge to grow your very own disembodied brain? If you’re one of those Mad Scientists of the garden, you may want to consider celosia, a plant that will definitely satisfy your craving for a little craziness in the yard.

Celosia Triple Threat

There are two species of celosia that have become popular in North American gardens: Celosia spicata and Celosia argentea. C. argentea can be further divided into the cristata group and the plumosa group. Spicata types are known as wheat celosia, because the plant produces flower spikes that resemble stalks of wheat. Celosia argentea var. plumosa is perhaps the most familiar species among gardeners, with their distinctive, brightly-coloured, plume-like flowers.

But it’s Celosia argentea var. cristata that really appeals to me; in fact, it’s one of my favourite bedding plants, period. In the greenhouse, we refer to the cristata form as “the brain plant,” for that’s exactly what the flowers look like – a disembodied brain, ridges, fissures and all, only with the same brilliant colours of the plumosa group. They look bizarre, with their vibrant colours and serpentine blooms, but they make outstanding bedding plants, and great cutflowers, too.

The flowers of the brain-type celosia owe their strange, convoluted appearance to a seed-borne mutation that causes fasciated growth – that is, growth that looks fused together rather than separated. Fasciated growth is evident on many plants, and occurs whenever cell division goes awry. Plum trees frequently display flattened branches and lily flowers often have flattened and fused flower heads, all due to cell mutations; the genetic machinery of these plants fell apart at some point in the growth cycle. The cristata types just happen to be fortunate enough that the mutation results in a form that is attractive to human beings – human beings who happily help the mutation perpetuate. Plant breeders love mutations like this, and they will expend plenty of time, labour and money to bring an attractive or unusual plant to market. In fact, mutations are one of the main sources of new plant varieties.

The cristata types not only have the cool brain flowers, but they also have very robust stems and leaves, because they have more chromosomes than most plants. Most plants (and human beings) get half their genes from their mothers and half from their fathers; each cell in the plant contains the chromosomes of each parent. Plants that follow this pattern are called diploids. But cristatas are polyploids, meaning that they have double or even quadruple the amount of genetic material per cell as diploid plants. When you cram that much DNA into one cell, you get a much huskier plant, which explains why the cristatas are much huskier-looking than the species types.

Polyploidy occurs naturally. Some of the most famous polyploids include strawberries and tart cherries, which both produce very plump fruit. But polyploidy isn’t always an advantage; polyploids frequently require a little extra water and nutrition to support their husky growth. That’s fine in the garden, since human beings will happily provide all the water and fertilizer the plant needs, but in the wild, polyploids are frequently less competitive than their scrawnier counterparts. Put a diploid and a polyploid of the same species in a nutrient-poor environment in the wild together, and the diploid is far more likely to get by on the available resources than the polyploid.

A Cerebral Flower

Celosia definitely puts on a bold statement in the garden, particularly the cristata type. If you’d like to try it, keep in mind that the plant is of tropical origin and enjoys warm temperatures; I’ve found that they perform best in containers in a sunny but wind-sheltered spot on the deck or patio.

I grow celosia not only for its looks, but because of the questions the unusual blooms raise from visitors. If you want to develop a reputation as a brainy gardener, you might as well try growing a brainy plant.

First Published 5/19/2005

Rose Foods

If you think choosing the perfect rose variety is difficult, just wait until you have to choose the right fertilizer. On a recent visit to a hardware store, I counted no less than ten fertilizers that were explicitly described as “rose food,” or at the very least sported a picture of a vibrant rose on the package. Each label implied that it was the best fertilizer for roses, yet the discrepancy in the nutrient analysis (the measure of nitrogen, phosphorus and potassium) from one product to the next was so great that the reasons for the proclaimed superiority of one rose food over another completely escaped me. One of the rose foods I saw had a formulation of 0-12-0 and claimed to encourage blooming. Another had an analysis of 18-24-16 and made exactly the same claim. Still another rose food label read 14-12-12, another 6-12-6, another 4-8-4. So how do you judge which rose food will really give your roses the nutrition they need?

Behind the Formulas

Well, to be fair to the manufacturers, they have no idea what your garden soil is like, so we shouldn’t expect them to create a “one size fits all” rose food. You may have beautiful, rich loam, or your soil may be more akin to impenetrable concrete. By law, a product claiming to be a fertilizer must provide at least some nutrients, and the nutrient percentage by weight must be specified on the label. As a result, just about any fertilizer will have at least a little positive effect on soil nutrient levels, regardless of soil type.

But there are a few flaws with many of the fertilizer formulations. First and foremost is the notion that phosphorus causes plants to bloom. Contrary to popular belief, phosphorus (indicated by the middle number on any fertilizer label) never has and never will be the direct cause of blooming. Phosphorus is part of the energy system of all plants and it is a key component of cell membranes and plant DNA. Plants deficient in phosphorus tend to look rather stunted, but surprisingly little phosphorus goes a long way; most soils on the Prairies benefit from the addition of phosphorus, but they don’t need to be inundated with it.

That being said, it’s not like 0-12-0 is some kind of snake oil. It has what it claims to have – 12% phosphorus (actually phosphate, which is oxygenated phosphorus) by volume – and phosphorus is important to plants. But don’t expect miraculous numbers of blooms to appear on your roses simply by applying this fertilizer. You may indeed have beautiful blooms on your roses after using it, but to attribute all the credit to the phosphorus actually shortchanges your own gardening skills.

Food for Thought?

Without knowing the physical and chemical properties of your soil, it’s impossible to say which particular fertilizer is best for your roses. When I’m growing roses in pots in my greenhouse, I know exactly what kind of fertilizer to add based on soil tests. As a result, I can fine tune the feed to the crop; I can either choose one specific fertilizer that mirrors the nutrients that are deficient in the soil, or if one fertilizer won’t address the deficiencies, I can apply a blend of fertilizers to accomplish the same goal.

Home gardeners don’t often have the luxury of soil tests, because accurate and regular tests are prohibitively expensive; if you’re only testing a couple of roses, the tests may cost you more than the plants. On the other hand, when you’re growing over two thousand roses, the investment is worth it.

The Right Fertilizer

Before choosing a fertilizer, make sure that you’ve got the rose basics covered. First, buy the highest quality roses that you can find. Transplant them in the best loamy soil possible, place them in the sunniest location you can find, and keep them well watered. Finally, once you’ve addressed all of these key aspects of growing great roses, I would simply apply any 20-20-20 fertilizer that contains iron. (All roses have a high demand for iron.) Yes, the phosphorus percentage in this formula is higher than strictly necessary, but it tends to stay put in the soil for future use by your roses anyway.

As for fertilizing, it’s a lot simpler job than you might think. I would fertilize throughout the spring, then stop in early August to allow the roses to harden off for the winter. That’s all you really need to do, nutritionally speaking, to grow great roses.

In our modern society, we’ve been conditioned to believe that there are quick and easy solutions to any problem. The truth is, I’ve yet to find any miracle product that can replace the basic pillars of good gardening: a good planting site, a top quality variety, and regular maintenance. In the end, choosing the right rose food isn’t nearly as important as addressing these fundamentals.

First Published 5/12/2005
Spring Hardiness

Most gardeners are familiar with the concept of winter hardiness – the ability of a perennial or tree to withstand the rigours of winter. But I think we need a new term to describe plants’ ability to handle the sudden highs and lows of our Prairie spring: spring hardiness.

Twenty-Five Percent Dead

A few days after our last blast of arctic air, I went for a short walk through the orchard on our farm. I found some fruit trees that failed to pass the spring hardiness test, including one of our pear trees, the “quad,” so named because it has four different pear varieties grafted onto it.

Each of the grafted varieties is supposed to be tough enough to handle a Prairie winter, and they are. But one of the four wasn’t well served by our recent cold snap. By late April this variety was in full bloom, while the other varieties were still just breaking flower buds. (This stage is referred to as the popcorn stage because the bud resembles slightly popped popcorn.) The fully-flowered variety still looked good from a distance, but up close the cold damage was readily apparent. The pollen-bearing structures, the anthers, were fine; they didn’t appear to suffer any obvious cold damage. But the carpels (the female flower parts that bear the fruit) were completely black, indicating irreparable cell damage.

Fortunately, the flowers on the other three varieties on the tree looked fine. The “popcorn”-stage flowers did have a few petals that were a touch brown, but when I unfolded the flowers and examined the carpels, I discovered that they were a rich, healthy green. These later-flowering varieties (including one great variety called “Ure”) aren’t any more resistant to cold than the damaged variety; they survived only because the floral structures hadn’t yet matured to the point where they were exposed and thus vulnerable to the cold.

Flowers in a Dangerous Time

In fact, many varieties of cherry, apricot, and pear are completely winter hardy in our region, but not necessarily spring hardy. For example, a Siberian pear species called Pyrus ussuriensis can easily withstand temperatures of minus 50 degrees C, but it struggles when grown in milder climates. Since these Siberian pears are used to long, uninterrupted sub-freezing temperatures, a prolonged warming spell signifies, to them, the arrival of spring. But a mild, coastal climate can experience prolonged warm spells in January or February that forces these trees out of dormancy. Any flowers that bloom during the warm spell will be quickly killed as soon as more typical winter temperatures return. Siberian pears (and many other northern fruit trees) do an excellent job of withstanding the deep cold of winter, but false springs are their undoing.

Preventative Measures

One of the biggest disappointments in gardening is a fruitless fruit tree. But the greater tragedy occurs when people spend huge amounts of time and energy in a pointless quest to “fix” the problem. Extra fertilizer, extra water, and who knows what oddball home remedies are undertaken in a vain effort to force the trees to produce fruit. Unfortunately, once a tree’s blooms have been killed, your only recourse is to hope for the best next season.

By and large, most of the trees and shrubs that bear edible fruit on the Prairies are well-adapted to our capricious spring weather. However, apricots, plums and pears often have trouble at this time of year, so if you’re planning on planting a fruit tree this year, try varieties that bloom a little later in the spring. If you do choose an early bloomer, try not to plant it in the hottest spot in the yard; you want to delay blooming, not hasten it. In the race to set fruit on the Prairies, it’s often the tortoise that triumphs over the hare.

First Published 5/5/2005
Juniper of All Trades

A number of years ago, my dear Great Aunt Anne inadvertently drove over one of Dad’s prized low-growing shrubs, flattening the branches to the ground. Fortunately, it was a juniper that felt the wrath of my aunt’s wheels. Junipers are among the toughest shrubs around, and while I wouldn’t advocate deliberately driving your car over one, Dad’s juniper recovered almost completely just a few short weeks after the accident. But junipers are more than just tough; they’re also one of the most versatile plants in the garden.

A Plant for All Seasons

The juniper is, without a doubt, the jack-of-all-trades of shrubs. You need a tall shrub? Plant a juniper. A groundcover? Juniper. A drought-tolerant plant? Juniper again. Junipers have a versatility that few other shrubs can match, which is why it is the most ubiquitous of all landscape evergreens.

The genus Juniperus encompasses a surprising variety of growth habits, from dense, spreading types only a few centimetres tall to striking pyramidal forms that can grow up to seven metres tall. Yet they all share needle-form or scaly foliage, and all are evergreens.

There are three species of junipers native to the Prairie provinces. Juniperus communis, or ground juniper, is a low-spreading juniper that forms carpets or clumps along the ground, growing to heights of about one metre. They can also be found all the way up to the tree line in the Rockies. J. scopulorum is also found in the Rockies (in fact, it’s known as the Rocky Mountain juniper), but this juniper grows into a small to medium height tree-form shrub. J. horizontalis, or creeping juniper, forms large mats and grows between one and three metres tall. Many of our best ornamental junipers were derived from extensive breeding of these three species.

Since junipers are such tough plants, they can be used to spruce up numerous difficult spots in the yard. For example, low-spreading junipers are well-adapted to dry or rocky low-fertility soils, and can mask these unsightly areas. That’s not to say that junipers grow best in poor soils; like most plants, they grow best in rich, loamy soils. But junipers are adaptable, and adjust well enough to trouble spots if you need the coverage.

Taller juniper species can be planted fairly closely together and used as a living fence. Some of the best junipers for hedges include ‘Table Top’, ‘Maney’, and ‘Mint Julep’ (also known as ‘Sea Green’).

A Hedging Alternative

Cedars (Thuja spp.) are also used for hedges, more so than junipers, probably because cedars generally grow taller and have thicker, rich green foliage. But on open, windswept areas of the Prairies, some cedar varieties have proven challenging to grow. They often suffer from winter injury, caused not by the intense cold, but by the long weeks of frozen soil and drying winds.

On the other hand, upright junipers (J. scopulorum) require less moisture and also seem to be more adept at retaining moisture than cedars. They don’t require pruning, and with their attractive blue-green foliage, they provide a show just as appealing as cedars. ‘Moonglow’ and ‘Skyrocket’ are excellent upright junipers, growing four to six metres tall.

Juniper Colours

Blue is the most common juniper colour; the best blues include ‘Wichita Blue’, ‘Blue Haven’, ‘Blue Arrow’ and ‘Blue Trail’. There are also quite a number of varieties with golden foliage, including ‘Gold Lace’, ‘Goldstar’, and ‘Mac’s Golden’, to name a few, all from the species J. chinensis. (It should be noted that the gold varieties are not as hardy as other junipers.) There are also a large number of grey and green juniper varieties.

Junipers and Jim

I’m particularly fond of junipers, perhaps because I can’t help noticing how great they look in their natural environment, without any help from human hands. Whenever I go hiking in the Rockies, I always take a moment to admire the tough junipers that inhabit the mountainsides. When we have junipers in stock at the nursery, I enjoy crushing the odd berry (actually, the berries are “spherical ovulate cones,” used, incidentally, to flavour gin). The woodsy smell brings back fond memories of those hiking trips.

But if the fragrance of junipers isn’t enough to entice you to grow them, then consider their remarkable versatility. Whether grown as hedges, groundcovers, topiaries, screens, masses, groups, or single specimens, junipers have something to offer to everyone.