KC Gardens

Those weeds in your garden? It may be best to let them be and here’s why

The best time to deal with dandelions is not now, but in the fall.
The best time to deal with dandelions is not now, but in the fall. Johnson County K-State Research and Extension

“Let it be, let it be. Speaking words of wisdom, let it be.”

I am struck by how valuable these words are from The Beatles. They can be applied to many aspects of our daily life, as well as the lawn and garden.

These words ring true for the weeds seen this time of year. Fall conditions were conducive for the development of some of our most troublesome weeds. These are often called winter annuals because they germinate in the cool, fall weather.

Then these weeds burst into a cacophony of spring color, including the purple flowering henbit, the yellow-green chickweed and the bright yellow dandelion. Dandelions are actually perennials, but we still lump them in this group.

No matter the weed, they are best controlled while small. The less time they have to establish a root system and build up energy, the easier to eradicate.

The hardest time to kill a weed is when it reaches maturity and begins flowering. The instinct for survival takes over and the plant uses stored food reserves to complete the life cycle, developing seeds for generations to come.

The lawn mower is your best defense against these weeds this late in the season. Mowing removes many of the flower buds and weakens the plant. Because henbit and chickweed are annuals, meaning they die after flowering, their life is over in just a few short weeks.

Treating perennial weeds like dandelions in the spring oftentimes only burns off the foliage. The plant will regrow from the root system. Many broadleaf herbicides work by tricking the plant into a phase of rapid cell division. The result is the curling, distortion of the foliage as the plant simply grows itself dead.

Spring applications of a broadleaf herbicide slow their development, but it may come at a price. Many of the products used to reduce weeds drift in the air as a vapor and are pulled into the stomata of nearby plants. The result is that non-target plants, trees, shrubs, flowers and vegetables may be similarly affected.

So it might be best to think twice about picking up the sprayer. If you must spray, do it on a cool, windless day. Use larger droplets of water from the spray nozzle and keep it as close to the ground as possible. This will help reduce drift vapors, which can travel in the breeze for blocks.

The best tip is to get out your calendar and scroll ahead to October. On or about Oct. 20, add this appointment: “Time to treat for spring flowering weeds.” Mid-October through early November is when germination has begun and the seedlings have not yet established. Spraying then will quickly kill most weeds.

Thank you, Beatles, for the inspiration to let it be. It is the best advice for a healthy lawn and landscape.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? You can also email them to garden.help@jocogov.org.

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