By Josie Borlongan, Garden Guides Contributor
A dandelion is a perennial weed with a stout taproot. The leaves are 5 to 25 cm long, simple and basal, entire or lobed, forming a rosette above the central taproot. The leaves are invasive, growing outward pushing down the surrounding vegetation, such as lawn grass, killing them due to lack of sunlight.
Dandelions have bright yellow flower head which is singly borne on a hollow stem. This single flower measures approximately 2 to 5cm and rises 4 to 30 cm above the leaves. The flower excretes a milky sap when broken. A rosette may produce several flowering stems at a time.
The dandelion is abundant everywhere but prefers chalks and loamy soils above pH 7.0. Dandelion is commonly found in pastures, lawns, orchards, hay fields, waste ground and roadsides.
Cultivation and Care
Dandelions are sown in spring in seed trays for transplanting, or in situ. Provide 14-inch (35cm) spaces in between plantings. In late summer, blanch in succession covering dry plants with a large, lightproof bucket. The dandelion leaves can then be harvested when they are creamy yellow and elongated.
Dandelions die back in the winter but will re-appear the following spring, continuing to grow for many years.
Dandelions are wind- or insect-pollinated. When the dandelion flower dries out for about 10 days, the seed-bearing white parachutes (dandelion clock) expand and lift out of the dried flower head. These parachutes are then carried by the wind or by birds that spread the seeds to the ground.
Weed Control Techniques
* Weed Killer/Herbicide: It is difficult to dig out dandelions completely, so before cultivating the soil, spray with a systemic weed killer and allow the weeds to die back completely before raking them away.
* Digging and Pulling: Dandelions are deep-rooted weeds that would need coaxing before they will even budge. Force a trowel or a narrow-bladed shovel into the ground alongside the weed's taproot. Get a firm grip on the plant's crown with one hand, as you lever the plant up with the trowel or shovel.
* Microwave/Solarization: Microwave treatment of soil in a controlled environment has killed dandelion plants when given a 16-second exposure.
* Note: Flame weeding is not an effective method to control dandelions for it can encourage re-growth when other surrounding vegetations are removed.
* Mulching: Adding mulch to cover crop residues reduces the emergence of dandelion seedlings.
* Biological Control: Birds, insects and rodents can reduce dandelion seeds by eating the seed. Sheep and geese that feed on dandelions have been used for the biological control of dandelion. Slugs find dandelion very tasty, so using them could help in the control of dandelion population.
* Another biological means is by using the soil-borne fungus Sclerotinia sclerotiorum. The fungus has reduced populations by 80 to 85 percent; but caution should be used since they not only destroy dandelions but other crops, such as lettuce, as well.