Killing Grass in Your Flower Beds

Every spring and summer people ask me, “What can I use to get rid of the grass that is creeping into my garden or flower beds?” I wish it were that easy as waving a wand. I will give you some things to try both organic and chemical, but understand that all of them need to be repeated as the grass comes back. Grass is extremely invasive.

Killing grass early in the season is hard because it isn’t really actively growing. It is starting to green up and grow, but the ground temperature isn’t warm enough to fully wake up the plant. In January the ground is extremely cold and that is why the grass isn’t green and growing but dormant and sleeping. As the ground starts to warm up, the grass starts to wake up and grow - taking up water and nutrients and slowly starting to turn green and grow. Grass is at its peak growing rate in the summer.

The killers that you put on to kill the grass have to be absorbed by the leaves and then translocate to the roots in order to kill the plant. If the ground is too cool, the plant will absorb too little of the killer. If the ground is warm, then the plant will absorb a lot of the killer and you will get better results.

These are control types generally available for homeowners. Remember that for these to be effective, they need to be sprayed on a actively growing plant leaf for the products to work. Spraying the ground does absolutely no good except the pre-emergence. I would still recommend using the pre-emergence controls along with the killers. A ounce of prevention is worth a pound of cure.

Here are some ways to get rid of the grass in your garden and flower beds:

Organic Control

Hand dig out the culprits.

- - Install a deep edging around your beds

- - Boiling water can be poured on a plant. It will kill the top of the plant, but not the roots. This is a good organic way to kill the top and starve the roots. In theory it sound good but won’t work like most people expect it to.

- - Vinegar is another organic way to kill any plant. It is another one that when sprayed on a plant will kill the top, but not the roots. Hopefully, when used a second or third time it will starve the root system and kill it. This method has become extremely popular because of the media attention it has gotten. It is worth a try. Make sure you are using horticultural vinegar. The stuff in the grocery store isn't strong enough.

- - Organic Pre-emergence, like Concern or Preen. If the grass is an annual type of grass (comes up from seed every year), then applying early in the year will prevent any seed from germinating- whether it be a grass seed, flower seed, or weed seed. The product will be most effective when you first put it down and get weaker as time goes on. It will last for about 3 months. If it is a perennial grass (comes back from the roots) the pre-emergence will not prevent it from coming up. Concern, Preen

Chemical Control

Pre-emergence - chemical version of the organic described above. High Yield is a readily available brand.

Glufosinate is a Glyphosate replacement. Unfortunately, glufosinate is not a systemic like glyphosate and is a top growth killer hoping to also starve the root systems.

Glyphosate is a systemic non selective killer that takes in the poison through the leaves and translocates it to the roots and kills the whole plant. It is highly effective and found in products like Roundup or Kleen-up. This is a non-discriminatory weed killer and will kill whatever it gets sprayed on, so use with care around your perennials.

Fluazifop-P-Butyl is a selective grass killer, found in Ortho Grass-b-Gone, that kills most grasses and shouldn’t hurt any broadleaf plant. If you were to use it….try a test area. It hasn't been tested on every plant you don't want any disasters! It usually has to be reapplied and should kill the grass and not your flowers.