Before you know it (it may have already happened), the first spring flowers will be shining forth. No, not spring Adonis, Kaufman tulips or forsythia. I’m thinking of the bright yellow, ubiquitous dandelion (Taraxacum officinale) – the bane of city parks, ditches and many lawns.
While they are considered a weed in many places and generally hated by homeowners everywhere, they do have a good side. Dandelions are a food source (nectar, pollen and leaves) for many insects, especially important for early foragers. The leaves – high in vitamins A and C and with more iron and calcium then spinach – can be eaten raw in salads or cooked. The flowers are an essential ingredient in dandelion wine, although they are used primarily to add flavour and colour rather than as a sugar source for fermentation yeast. The roots can be roasted and ground to be used as a coffee substitute. And finally, the “officinale” part of its Latin name refers to its centuries long and continuing use as a medicinal plant.
Like many weeds, dandelions are opportunists, becoming established fastest were there is low plant competition (e.g. weak lawns) and on disturbed (e.g a garden) or bare soil. And they attack en masse. Each seed head produces between 50 and 150 seeds, with each plant capable of producing up to 5,000 seeds per season. The seeds themselves can lie dormant for several years, waiting for opportunity to knock.
Understanding dandelion biology provides some clues on how to hold it in check. Start with prevention by keeping your lawn healthy with proper maintenance (fertilizer, water, mowing) to reduce opportunities for establishment. Be vigilant: root out early invaders, getting the entire taproot. Same with established plants – dig down with a trowel or use a dandelion removal tool (various options available). Broken-off roots will re-sprout like the mythical many-headed hydra in short order.
Prevent dandelion seed germination by applying corn gluten to your lawn. Corn gluten, an organic weed control option, inhibits seedling root formation. Apply in early spring, coinciding with the peak of dandelion flowering. Besides acting a pre-emergent herbicide, corn gluten breaks down into an organic nitrogen source over a few weeks. If planning to reseed areas of your lawn after a difficult winter or to cover up dog piddle spots, do not apply corn gluten six weeks before or two weeks after topdressing.
If your dandelions are out of control and digging them up stopped being an option, there is the chemical route of course. (Note: always follow label instructions and wear recommended protective clothing when applying.) The most common lawn weed killer is a cocktail of 2,4-D, mecoprop and dicamba (e.g Killex, Weedout, Weedex, Smartones and Clearchoice). It kills many broadleaf weeds but grass is unharmed. 2,4-D is the only chemical found in the Weedex dandelion bar and stick but no mixing or spraying is required. Glyphosate (e.g. Roundup), if applied carefully with a spray-bottle to individual dandelions, will kill them usually with one application. Expect some collateral damage to your lawn, but these areas should fill in quickly with proper lawn care and maintenance. Horticultural-strength acetic acid is applied similarly with a spray bottle with similar incidental lawn damage.
Soon, a biological dandelion control product will be available for homeowners, turf growers and golf courses. Dr. Karen Bailey (ret.) and her associates at Agriculture and Agri-Food Canada discovered a fungus (Phoma macrostoma) in 1985 that attacked dandelions and thistles. After years of research and developing a shelf-stable granular formulation, a commercial partner (Scott Co.) licensed the technology and recently registered three products.
Did you know? The name dandelion is derived from one of its French names, dent-de-lion, meaning lion’s tooth in reference to the toothy leaf margins.
— This column is provided courtesy of the Saskatchewan Perennial Society (www.saskperennial.ca; email@example.com). Check out our Bulletin Board or Calendar for several upcoming garden information sessions and other horticulture events in April.