First Published 3/31/2005
Composting Weeds

Composting is a great way to convert a wide array of waste materials such as fallen leaves, banana peels, and lawn clippings into a valuable resource. Still, there’s one source of organic matter that’s a little suspect as a compostable material: weeds. But is it justifiable to banish weeds from the compost bin as thoroughly as we try to banish them from our gardens? Or can weeds be safely added to compost?

Give Weeds a Chance

I’ve been asked many times if weeds can be thrown into the compost bin, and for gardeners new to composting, I typically answer with a simple “No.” Weeds, like most other plants, produce seeds, and those seeds could be sown back into the garden right along with the compost.

But that’s assuming that seed bearing weeds were put into the compost, and that if there were seeds, they were viable after composting. Agriculture Canada did some investigation of the viability of weed seeds in compost and came up with some interesting data.

First, weed seeds are highly variable in their ability to withstand the high temperatures inherent in the composting process. Some species of weeds, including wild mustard and stork’s-bill, were killed early in the composting process, with the temperature held at just 39 degrees C for a week – a fairly low temperature for compost piles, which should be generating temperatures of 55-60 degrees C. Stinkweed and green smartweed, two of the more common urban weeds, took longer to cook in compost. Some of the weed seeds were still viable after forty-two days in the bin – not a lot of seeds, but still enough to possibly re-infest the garden should the compost be spread back into the soil.

Grassy weed seeds such as foxtail barley and wild oats – weeds common to anyone gardening in rural areas – took fewer days to succumb to the effects of composting than the broadleaf weeds found in urban gardens.

Composting with Weeds

The key to enjoying a high rate of success with weed composting is to ensure that the pile of organic matter is indeed undergoing the composting process. In other words, heat must be generated. A good quality soil thermometer that can be stuck into the compost pile will show if the right blend of water, organic matter and microorganisms is creating temperatures high enough to compost the organic material. The temperature reading should climb into the 55-60 degrees C range, indicating that microorganisms are hard at work, breaking down organic matter – including many weed seeds – into rich compost.

If you think that you’d like to try composting weeds, be cautious. The best way to avoid introducing weed seeds back into your garden with the compost is to avoid adding mature, seed-bearing weeds to the compost pile in the first place. Pull all weeds before they set seed, and only then add them to the compost bin.

If, on the other hand, you’d like to try composting seed-bearing weeds, I would recommend a separate composter that you can leave for several months. When you’re ready to use the compost, spread it into a few seedling trays and look for any signs of germinating weeds. If the compost fails to produce viable seedlings within a week or two, the compost is probably pretty darn clean, and safe to add to your garden.

Of course, the only certain way to assure that you have a 0% chance of introducing weed seeds from the composter into your garden is simply to never let any of your weeds reach the seed-bearing stage in the first place. But who among us can claim that we’ve never allowed at least a few weeds to grow to maturity in our yards? I can say with certainty that that’s a pretty select list – and I’m not on it!

First Published 3/24/2005
Easter Lilies

You don’t have to be a mind reader to identify someone who loves to inhale the incredible fragrance of Easter lilies. The evidence is as plain as the nose on their face – literally. Easter lilies produce copious amounts of pollen, which will leave very conspicuous golden blotches on the nose of anyone who sticks it a little too far into the big, white blooms. It’s a common occurrence around the greenhouse, and every spring at least a few customers or employees fall victim to the lilies’ trap.

But there’s more to lilies than entertainment value; they have a fascinating history, too.

The Road to Tradition

The Easter lily – Lilium longiflorum – is noted for its attractive, sword-shaped leaves and very large, white blooms. It is, of course, a symbol of Easter in many nations, thanks to its white flowers (symbolizing purity) and the fact that those beautiful blooms appear in the early spring.

Surprisingly, Easter lilies are native not to any of the nations where Christianity took root, but to the Ryukyu Islands of Japan, as well as Okinawa. They were introduced to the British Isles in 1819, and to Bermuda in 1853, where the climate was excellent for Easter lily cultivation. (For this reason, the plants are sometimes referred to as Bermuda lilies.) But the burgeoning North American lily industry was ruined by virus and nematode invasions in 1898, and the Japanese became the leading exporters of the plant for the next forty years or so. During world war II, the Japanese stopped exporting Easter lilies to Allied nations, and Easter lily bulbs became so valuable that they were referred to as “white gold.” It was only thanks to Louis Houghton, a veteran of World War I, that the Easter lily supply wasn’t completely cut off; back in 1919, he had brought a few bulbs with him from abroad to share with friends and family in Oregon. With the traditional source of Easter lilies no longer available, the tiny lily industry of the Pacific Northwest – with a climate very similar to Japan’s and thus fertile ground for the plants – took off, and it is now the world’s primary source of Easter lilies.

Shopping for Easter Lilies

When purchasing an Easter lily, look for plants with rich, green foliage throughout the leafy canopy, and count the flower buds; a high quality lily will have six to eight buds. (I have a few hidden away in the greenhouse with ten buds!) This past week the flower buds of our Easter lilies have been growing at a stunning rate of 1 centimetre per day, and will terminate at around 17 centimetres just prior to opening. All of these buds will eventually open and flower, and many buds flower successively, so the higher the bud count, the longer you’ll enjoy the stunning floral display.

If you’re buying a couple of Easter lilies, choose one that has perhaps one bud that’s just on the verge of flowering and one that is in the tight bud stage. That way you’ll have many weeks of enjoyment, with flowers blooming well beyond the Easter weekend.

A lily bud that is swollen and eager to flower will take from four to seven days before the flower opens up. To hold flowers for the longest period of time in the home, cooler room temperatures are better. If you can stand nighttime temperatures of 18 degrees C, the lily flowers will last longer than if you crank the temperature up to a more comfortable 24 degrees. You’ll have to decide if the tradeoff between personal comfort and flower longevity is worth it.

Sometimes people ask if they can plant their Easter lilies in the garden after they’ve finished flowering. You can; I’ve talked to several Prairie gardeners who have successfully overwintered Easter lilies outdoors, growing them as perennials. With lots of snow cover and a mild winter it can be done, but the odds of success over consecutive winters are pretty long. Plus, if you want them to bloom next Easter, the bulbs must be dug up in the fall and stored, and then planted in a greenhouse in January. It’s a far more arduous task than most gardeners are willing to undertake.

Easter Entertainment

Easter lilies are great for many reasons: the wonderful fragrance, the attractive green foliage, and the huge, creamy white blooms are reason enough to set aside a spot in your home for them. But there’s also the chance to enjoy a good chuckle when a visitor takes a deep sniff and gives himself the “mark of the lily!”

First Published 3/17/2005
The Secret of Shamrocks

This being St. Patrick’s Day, it seems like a good time to investigate that most famous of Irish symbols, the shamrock.

Cutting Through the Blarney

The name “shamrock” is purported to come from the Irish Gaelic “seamrog,” meaning “little clover.” But beyond that, the shamrock story gets a little fuzzy. The truth is, the secret identity of the shamrock is something no one has nailed down with absolute certainty. Several different plants have claimed the shamrock name, but in fact, there is no true shamrock species. “Shamrock” is simply a description of a certain narrow group of plants, plants that are small, low-growing, and trifoliate – that is, they have three-lobed leaves. (Occasionally, a trifoliate plant will produce an extra lobe, becoming the highly prized four-leaf clover.)

Even the Irish themselves can’t agree on which species of plant is the true shamrock. When Irish pollsters asked their countrymen which plant deserved the name, the results were far from unanimous. The two most popular choices were species from the clover family: Trifolium dubium (lesser trefoil) and Trifolium repens (white clover). These two species captured about 80% of the vote, while other species such as Oxalis acetosella (wood sorrel), Trifolium pratense (red clover), and Medicap lupulina (black medick) made up the remaining 20%.

More Than Just a Pretty Face

Whatever the species, all plants that have earned the name shamrock have one thing in common: an abundance of three-lobed leaves that retain their green colour even in nitrogen-poor soils. That’s because clovers “pack their own lunch,” so to speak: they belong to the legume family, and legumes are noted for their ability to “fix” nitrogen – that is, to transform gaseous nitrogen in the soil into a form that plants can actually use as a nutrient. Legumes (or more accurately, the microbes found on legume roots) can take nitrogen from the air contained in soil’s pore spaces and convert it into nitrogen containing ammonium. The plants can then use the ammonium as building blocks for a wide array of essential compounds, including proteins, enzymes and plant hormones.

Canada’s Shamrock

The one species of shamrock that Canadians are most familiar with is Trifolium repens. Indigenous to Europe, it too finished quite high on the Irish shamrock survey (almost as high as Trifolium dubium), and it has adapted so well to our climate that it’s been classified as an invasive weed of lawns.

Portions of the lawn can be choked out by clover (making me wonder if clover really is all that lucky!), but there is an upside – when the clover roots eventually die, they release nitrogen compounds back into the soil, which the remaining grass can utilize.

So this summer, if your neighbour makes disparaging remarks about your clover-infested lawn, you can pursue one of two strategies. Either tell her that the clover she is referring to is in fact a collection of shamrocks, and that to destroy them would be bad luck, or you could expound on the science of legumes and nitrogen fixation.

Of course, if you don’t have invasive clover in your lawn, you can still consider yourself fortunate. Maybe that’s what they mean by the luck of the Irish…

First Published 3/10/2005
Breaking the Crust

Up on the hill of my parents’ farm, the rich, clay loam soil has supported fantastic crops for many years, and continues to do so to this day. However, that clay loam had an alter ego: under the right conditions, it could transform from soft and supportive to unbearably crusty.

The Upper Crust

Anyone familiar with clay is familiar with soil crust. A soil crust is a thick layer of hard, impermeable clay that makes cultivation a nightmare. Crusts are particularly evident in the spring as the snow melts, or a day or two after a heavy rain. The soil develops a patchwork of irregularly-shaped plates that make the ground look a bit like a jigsaw puzzle, each “piece” separated by deep fissures.

Many plants, particularly seedlings, find it difficult to penetrate through crusts. Some seedlings escape via the fissures, but seeds, tubers or bulbs unlucky enough to be situated right underneath a plate labour so intensively to push their way through the crust that many simply burn out before ever seeing the light of day. I’ll never forget flipping over clods of crusted soil on our vegetable farm in the spring and discovering onion and carrot seedlings that had germinated perfectly, and yet were unable to emerge through the crust. All we could do was break up the soil and reseed.

Bulb Breakthrough

Some of the most popular spring flowering bulbs have varying degrees of success dealing with clay crusts. If you’re growing tulips, narcissus, or irises, take heart – these bulbs have adapted quite well to the problem of crusty soils. All three genuses have sheath leaves, which are tough, bayonet-like leaves that thrust upward and break through the crust, allowing the more tender leaves easier access to the surface. Other bulbs, such as anemones and aconitum, have no sheath leaves and have a much harder time breaking through soil crusts.

But even bulbs with sheath leaves have a hard time breaking through thick, heavy crusts. I’ve seen very distorted tulips with rough, twisted leaves growing in heavy clay soils, confirmation that the plants won the struggle to emerge through the crust, but did not escape that battle unscathed!

Correcting Clay

Clay is often demonized because of its tendency to produce crusts, but in moderation clay is a valuable soil component. High quality loam soils contain a fair bit of clay; part of the reason that such soils produce good crops is because the clay holds a lot of water in the soil, providing a reservoir for plants that doesn’t exist in sandy soils. It’s only when the clay content ventures into the 30-40% range and above that it starts to negatively affect soil quality.

The method for correcting a crust problem in the garden depends on the quantity of clay in the soil. A soil that is around 90% clay is unsuitable for gardening. It’s virtually impossible to amend soils so dominated by clay. Adding sand is often touted as a remedy for clay soils, but when clay content is that high, it just won’t work. Unless a tremendous amount of sand is added (about 50% sand by soil volume), all you end up with a bunch of sand particles surrounded by clay; the resulting soil has the consistency of concrete. The only option is to remove the clay and replace it with a truckload or two of high quality loam. This may be an expensive solution, but it’s far easier on the blood pressure than years of frustrated ambitions in the garden.

If, on the other hand, you have clay loam like that of my parents’ farm, with a clay content of around 30%, adding compost, well-rotted manure, or simply more loam to the soil will help. The humus in the organic matter binds itself to the clay particles, preventing those particles from binding together. The result is a nice, soft, permeable soil that lets water and nutrients flow into and through the soil, and allows seedlings up out of the soil.

Clay is not a villain in the garden, provided it isn’t overwhelmingly dominant in your soil. With clay, a little goes a long way.

First Published 3/3/2005
Juvenility

Juvenility is a growing phenomenon in the garden – and I mean that literally.

In the plant world, juvenility doesn’t refer to those times when you throw a temper tantrum because your dog has chewed up your favourite dahlia. Juvenility actually refers to how much growth a plant needs to develop before it can produce flowers. Nothing – not extra fertilizer, nor extra water, nor soothing music nor homemade remedies – will coax these plants into blooming. Only the passage of time can “cure” the juvenile phase.

Juvenile Behavior

Anyone who’s grown a corn plant knows that if you sow seed in May, you don’t expect cobs to form in June, when the plants may only be knee-high. This is because the corn must pass through its juvenile stage first.

Sometimes getting past juvenility is as simple as a matter of developing a minimum and absolute number of leaves.

Indoor plants such as clivias require a minimum of six pairs of their long, strap-like leaves before they can produce their flower spikes. Nothing can force them into flowering before those six pairs develop. The popular Wave petunias require even more leaves before they will flower – thirteen, to be precise. Several varieties of cauliflower must produce nineteen leaves before a single curd will sprout.

Some plants spend less time as juveniles than others. Impatiens flower at an incredibly small size, when the plants are no larger than a quarter in diameter – it’s almost as if they’re flowering at the seedling stage. Celosia and mimulus have similarly brief juvenile periods.

No Parallels Here

It’s tempting to compare juvenility in plants to adolescence in humans, but the reality is much more complex. With adolescent humans, we think of the entire body as being at more or less the same stage of development. But with plants, different tissues often coexist at different levels of maturity. For example, an apple tree may have juvenile suckers arising from its base, and mature upper branches that produce fruit.

There can also be a huge range in juvenility between closely related plants. Some pines will yield a few mature cone-bearing branches in their first year of growth, while others won’t produce their first cones for up to 45 years.

The Need to Know

Understanding juvenility is not just an academic exercise. Gardeners trying to take cuttings from their plants, for example, should know that both hardwood and softwood cuttings will root better if they are taken at the juvenile rather than the mature stage. Choosing juvenile over mature cuttings can mean the difference between success and failure. Moreover, if you know when to expect your plants to enter the mature phase, you’ll know not to waste water and fertilizer on them in a futile effort to get them to bloom. (Conversely, if your plants have reached what you know is a mature stage and have yet failed to bloom, you have a good indication that there may be a genuine problem.)

Other Factors

Of course, with many plants juvenility is far from the only factor that determines when flowers will appear. Day length, sunlight intensity, and temperature are just some of the other factors that come into play as plants struggle to leave their juvenile days behind. In this way, at least, plants are like people – sometimes they just need time to get past their juvenile phase before they can really blossom.