With all this cool rainy weather, the return of a perennial “favourite” was inevitable. The word favourite is said tongue-in-cheek. The dreaded dandelion is the gardener’s first gasp of a new growing season.
The common dandelion (Taraxacum officinale) is a biennial or perennial herbaceous weed, with long spear-like leaves. Those leaves are so deeply toothed, that the plant was given a common name “Dent-de-lion” which refers to a lion’s tooth in old French.
Like so many other invasives, dandelions were introduced from Europe. It was hoped that they would provide nectar for imported honeybees. The plant became so prolific that it virtually grows worldwide.
Many gardeners acknowledge that those broadleaf perennials can be difficult to control, and will virtually grow under the most adverse conditions. Once established, the only way to eradicate them is by physical effort or chemical means. In our area, commercial toxic chemicals are not available for the home gardener.
Unlike most other seeds, dandelions germinate without long periods of dormancy. To further increase reproductive efficiency, seeds develop without pollination.
The major conundrum is that the seeds are easily dispersed by the wind. Clouds of floating fluff can be seen shortly after seed heads have completely dried out.
Unless the seed head is completely captured and destroyed, it will regenerate. The head should never be placed in a compost pile as it will eventually reinstate itself once the dormant seed has found its way to soil. Seeds can lie dormant for years.
The dandelion has been used by numerous civilizations since the 10th century. It has been recorded as a medicinal herb in Chinese, Arabic, and then European history – most notably, as a natural diuretic that promotes water and salt extraction from the body.
Chinese medicine and modern day herbalists still use the root. The leaves are eaten in various forms.
As dandelions are highly adaptable plants and are able to root in a variety of conditions, removal can be difficult. Taproots commonly grow 6 to 18cm deep. If the entire root is not removed, it will regenerate and grow into a mature plant.
Awareness is the key when working with them in the garden and lawn. Pulling out the entire root is the best form of organic control. As with all weeding, moist or loose soil makes that labour-intensive process much easier. Smaller plants or ones without blooms will be much easier to remove. Larger plants will require a spade inserted deeply into the soil and with a prying motion loosen the soil around the large taproot. Grasp the stem close to the ground and lightly pull. Repeat the process if necessary. Definitely try to remove the entire root.
Although not as labour-intensive, a good control for larger patches or lawns is to use a mower as often as possible. Begin the process just before the blooms start and continue every one or two days after. In the heavy growing season, continue to cut as soon as flowers surface. That will prevent the blossoms maturing into seeds.
The plant is so prolific that it will require daily attention. Always be on the lookout for telltale signs.
Horticultural vinegar is useful form of weed control. Spraying it directly onto the leaves will only stunt the upper portion of the plant and not the root. The acid in the vinegar resembles a herbicide that kills the leaves but does not persist in the soil or cause water or other pollution.
Heavily mulching an infected area will begin the process of smothering the plants and eventually killing them. All plants require some level of light for germination and continued growth. The process of photosynthesis will not continue if the ground has been heavily mulched or if weighed down black plastic.
Applying corn gluten meal is the organic response to weed and feed. It acts only on emerging seeds and not on established plants. Corn gluten meal prevents roots from forming during seed germination. If a root can’t grow, the seedling is unable to obtain water or nourishment from the soil. It can be applied to soil or on lawns four to six weeks before dandelions germinate.
The site of a few misplaced dandelions can easily ruin the entire look of a carefully cultivated lawn or garden. Those glowing ethereal yellow blooms can be very persistent and difficult to control. Unfortunately, wind dispersal propels seeds from neighbouring properties where the culprits are free to run wild. They will inevitably land where they are not welcome.
Ron Stevenson is a member of the Fergus Horticultural Society
