Controlling weedy foes in the garden

Weeds seem to occupy the minds of gardeners for a great deal of the growing season.

There are weeds in the landscape, weeds in the vegetable garden, weeds in the lawns … weeds, weeds and more weeds.

Some people let the weeds preoccupy them for most of the gardening season, while others really couldn’t care less.

Sometimes I just shake my head as I see shoppers at garden centers filling their carts full of all manner of weed killers to bombard their weedy foes.

Sure, sometimes you’ve got to do what you’ve got to do to take care of problem weeds.

But many problems can be avoided with proper planning, reducing both impacts to the environment and the wallet.

As wise Ben Franklin once said, “An ounce of prevention is worth a pound of cure.”

In weed control, this is certainly true.

Preventing weedy invaders

Keeping weeds out the garden and lawn is certainly easier than fighting them once they get there.

To get established, weeds need the same things that garden plants do — space, water, sunlight and food.

Weed prevention means limiting at least one of these from the weed seed or root to keep the weed from taking hold.

Mulching not only preserves water, as we discussed last week, but also reduces weeds by making open space unavailable.

Mulch chokes out weeds by keeping weed seeds from finding a good place to germinate and weed shoots from coming up.

Besides the wood mulches that you think about, there are other mulching techniques to take care of pesky unwanted plants.

Using a solid mulch beneath the wood mulch can go a long way in increasing weed suppression.

You can use landscape fabric, a black cloth that allows water through, in areas where you have planted perennials.

I would suggest not using in areas subject to frequent change, since it is a pain to deal with.

If you are looking for something less permanent to get your weed suppression off to a start, several layers of newspaper or even thick cardboard to suppress existing weeds.

In the vegetable garden, I like to use shredded newspaper as mulch.

It is basically free and reuses something that would otherwise be thrown out.

All I do is run it through the shredder that you have to shred your junk mail. It creates wonderful mulch. Straw also makes a good mulch for the veggie garden.

The next easiest way to prevent weeds is by denying them sunlight. Plantings that cast heavy shade on the ground can help reduce the number of weeds that grow under the plants. Closer plant spacing helps to do this, whether in the landscape or the vegetable garden.

This is another benefit of raised beds — since the whole garden area is planted and there aren’t rows open to sunlight.

This technique is also employed in the lawn.

When experts recommend a higher mowing height, it is mainly to increase the grass canopy and shade the soil. Proper mowing height also makes grass healthier, and it outcompetes weeds for space

Controlling weeds

Once you have weeds, there are a few methods to use to control them. Hand pulling and cultivation with a hoe or tiller are still pretty effective, albeit labor intensive, ways to deal with weeds.

By combining prevention techniques with these manual techniques, though, you can reduce the amount of work needed while also reducing chemical use.

If you have to resort to chemicals, using the most-effective least-toxic option is best.

Control options also depend on whether the weed is an annual or a perennial. Annual weeds — like crabgrass, chickweed, purple deadnettle and lambs quarter — can be controlled with a pre-emergent herbicide like the chemical trifluralin, which is the active ingredient in products like Preen.

This product needs to be applied before weeds germinate in the spring, but it will prevent seeds you plant from germinating as well.

There has been a lot of information floating around about the use of both corn gluten meal and vinegar to control weeds.

Sadly, these methods are not as effective as reported.

The use of corn gluten as a weed preventative was successful in greenhouse trials in the Midwest, but they have not been replicated in other parts of the country. Most likely it is a climate difference. Researchers have even struggled to replicate the success in the Midwest.

Vinegar will burn back some plant leaves if applied during bright, sunny days but does not kill the whole weed. High-strength vinegars are sold as weed controls, but can have just as many damaging issues as chemical controls.

Established perennial weeds like dandelions and ground ivy will require either a broadleaf herbicide or a broad-spectrum herbicide.

Broadleaf herbicides like 2,4-D kill broad-leaved plants in lawns but do not damage grasses.

The down side is that they will also damage or kill any plants that you may have in your landscape if they make contact.

Broad-spectrum herbicides, like glyphosate (Roundup) will damage or kill all plants they come in contact with. Unfortunately, there really isn’t a chemical you can apply that will kill only the bad guys and save the good guys. That’s why it is always advisable to prevent weeds first, then deal with the ones you have safely.

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