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Using Herbicides Wisely

grass weeds, turf weeds, lawn weeds

If you choose to do nothing about weeds, just like a pacifist country, eventually you will be overrun with expansionist opportunists. If you want a nice turf grass lawn, being passive is not an option. If you don’t fight for territory on a regular basis, you will lose the space to weeds and brambles, and eventually tree seedlings. The outdoors is a dynamic environment with shifts in dominance during each season. Know your enemy. If turf weeds are the enemy, then you need to become familiar with how they battle for the ground plane territory of your lawn.

One of your choices when you join in the fray is the level of quality which you are willing to accept. You can decide to accept all green plants that stay under four to six inches in height by simply mowing frequently during the growing season at a set height. That’s fine. Lots of people do this as their single engagement with their lawn. By choosing mowing as your only cultural practice, you are accepting variations in texture and color, along with a significant amount of bare spots in the winter as the summer annual weeds decline. This is a perfectly reasonable choice which complies with local ordinances and most neighborhood covenants.

If you decide to bump up the quality and go for a more uniform look for your lawn, then herbicides need to be added to your arsenal. But, for goodness sake, learn how to use them properly! Follow the label directions. Just as you wouldn’t go into battle shooting randomly in the air rather than targeting the enemy, you shouldn’t start spraying chemicals with abandon. It’s dangerous, and you might end up harming the very thing you’re trying to protect. Hiring mercenaries—lawn care companies might be an effective strategy, but at great cost. They will have their own agenda, and might not be as surgical and eco-friendly as you would like. Here’s how to use herbicides wisely, without having to become a chemical engineer.

First, hand weed as much as it is practical. It may surprise some people, but it is possible to remove lawn weeds without spraying with any toxic chemicals at all! If you have very few weeds, then get a weeding tool, and pluck out the offender before it ever has a chance to flower and go to seed. It’s best to put weeds in the trash or compost heap rather than placing them back on the ground where they might spread new babies everywhere. But, even with hand weeding, which helps stop weed seed dispersal, you will probably need more action to fight the weed battle.

You can spot-treat weeds using a selective herbicide. They’re called selective because they kill the weeds and don’t harm the turf grass. They have been formulated, typically, to kill only broad-leaf plants. Grasses are monocots and broad leaf plants are dicots, so they sprout from one leaf rather than two. This difference is very important, because chemical companies can create herbicide formulas that can reliably target one kind or the other. That’s great for you, because you typically only want to get rid of the plants that don’t look like grass (dicots). The problem with selective herbicides is that weeds never stop sprouting. You only get a kill for the grasses that sprouted this week. Next week there will be a whole new set of weeds, and more the week after that. The truth is, you only get two or three days of effectiveness. You don’t want to be putting toxic chemical on your lawn every few days, and you don’t want to battle weeds the entire growing season.

Your best and most effective battle plan is to deter new weeds, rather than attempting to eliminate them after they have arrived. Be smart and apply your money and your time and your efforts on prevention. Use pre-emergent herbicides. They prevent new weeds from sprouting for an entire season. Because selective herbicides are only effective for a few days, you must apply pre-emergent control during the short window of opportunity after their use—unless you apply it before each season begins.

There are only two weed seasons—warm and cool, so you only need to apply pre-emergent herbicides twice each year. The first season is the warm season, which lasts from the time the Forsythia and Daffodils bloom in the spring until the leaves start to turn in the fall. There is an overlap. The second season starts just about the time summer vacation ends in late summer until the Azaleas start to bloom the following spring. Weeds are very sneaky! The trick is to put down pre-emergent weed preventers a week or two before each season begins. If you aren’t the early bird, you can still use them, but you will have allowed one or two generations of this year’s weeds to have sprouted.

The warm and cool season calendar dates may seem a bit unclear. They will vary depending on where you live and depending on fluctuations in weather patterns. The key temperature seems to be about 80 degrees Fahrenheit.  If you have more than one or two days above 80, then the warm season has begun. If you have one or two days below 80, then the cool season is blowing in. The changes in soil temperatures tell the weed seeds to wake or sleep, depending on their temperature preferences. The seeds are always there, and they remain viable for hundreds of years, so eliminating the seeds is not an option. The next best thing is preventing them from sprouting.

There will always be turf wars, unfortunately. Control the outcome by keeping the battleground as small as possible and by being strategic about how you fight weeds.

It is very difficult to find pre-emergent herbicides. Manufacturers are more than happy to provide you with “weed and feed” products, where pre-emergent herbicides are mixed in with strong fertilizers. Pre-emergent herbicides need to be applied long before it is safe to hype up the fresh growth of turf grasses. Fertilizer applied too soon causes die back of your lawn during inevitable cold snaps during early spring and late fall. You end up with huge dead spots in your lawn right at the time the weather breaks. You can purchase grass seed (from the same manufacturers) to fill in the dead spots.  Hmmm…..

Never use weed and feed products! Use lawn chemicals wisely, and hunt down a source of pre-emergent herbicide that has no fertilizer included. 


Do you have good ideas on how to win the war on lawn weeds? Submit your comments and suggestions. Thanks!

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