Tuesday, June 23, 2015

How to Kill Bermuda Grass in 10 Easy Steps

In its proper place, Bermuda grass (Cynodon dactylon) makes a good lawn or good pasture. Unfortunately it doesn't stay in its proper place. The underground roots and the above ground runners spread everywhere. Soon you have Bermuda grass erupting from your flower beds, creeping through your cactus, tangling in your shrubs and even invading your garden shed.

Killing Bermuda grass is not difficult, but it's not going to happen overnight. I'm a desert landscaper. I spend a lot of time killing lawns, especially Bermuda grass lawns, to replace them groundcovers that use less water. I have learned that no matter what the herbicide package says, it will take at least a month and several applications of herbicide to kill 90 to 95% of the Bermuda grass, then several months of spot application on surviving sprigs to get the remainder. It's a tough plant. It's so tough that it grows in the cracks of the concrete medians in the middle of a Phoenix freeway.

Bermuda Grass with seed heads
By Harry Rose from South West Rocks, Australia via Wikimedia Commons

How to Not Kill Bermuda Grass

The most frequent mistake people make when they try to kill Bermuda grass is to pull out, mow down, or clip off as much visible growth as possible, then use an herbicide "to finish the job". Herbicides must be absorbed by the leaves to be effective. If you remove most of the leaves before you apply the herbicide, very little of the herbicide will be absorbed. The grass will regrow from the roots.

The second most common mistake is to try to kill the Bermuda grass by withholding water, then resorting to herbicides when the grass refuses to die. This is a native of the African savannah, where 6 months without rain is normal. You aren't going to kill it by shutting off the sprinkler for a few weeks. Bermuda grass can survive herbicides better when it is water-deprived because it absorbs less herbicide when it is dormant from drought.

A third mistake is trying to kill Bermuda grass during cool weather. The days and nights must be warm enough that the Bermuda grass is actively growing. Let it "green up", and don't start killing the lawn unless you have at least 6 weeks of warm weather left.

How to REALLY Kill Bermuda Grass

When the grass is green and actively growing, follow these steps:
  1. Water the Bermuda grass thoroughly to encourage it to grow. Herbicides work best when the plants are actively growing.

  2. Wait a week, water the Bermuda grass in the morning.

  3. The following morning, thoroughly spray the Bermuda grass with an herbicide that contains glyphosate. Make sure you follow the package directions for diluting the herbicide. Spray the grass thoroughly, making sure you cover all the leaves.

  4. Wait at least three days to give the herbicide time to be absorbed and spread through the plant tissues.

  5. Now you can yank, clip and mow, because the herbicide has spread into the roots.

  6. Keep watering deeply every few days, as if you were trying to grow the best lawn on the block.

  7. Give the survivors a week or so to grow some leaves, then spray them with the herbicide again.

  8. Repeat the cycle of water, herbicide, water, herbicide until the sprouts stop appearing.

  9. Patrol the area for the next two or three growing seasons and apply herbicide to any new sprouts. The roots of Bermuda grass can be as deep as six feet, and they persist for several years.

About Glyphosate

Glyphosate kills plants by shutting down an important metabolic pathway. Insects, birds, and mammals do not have that pathway, so glyphosate is safer to use than some herbicides. However, follow the precautions in the instructions for diluting, applying and cleaning spray equipment.

Glyphosate was first introduced by Monsanto as Roundup® but the patent has expired and it is available from various manufacturers. For the most cost-effective herbicide, look for a brand with the highest concentration of glyphosate, then dilute it according to the package directions. The Roundup® brand now has a second herbicide to make it look like the Roundup® is working quickly, but it's no more effective than the bargain generic.

CAUTION: Glyphosate kills almost all plants, and even a small amount of spray will retard their growth. Do not spray herbicides on breezy days. Protect the plants you do not want to kill with a shield. I slide paper bags over small plants and drop a box or trashcan over larger ones, spray the nearby weeds, then remove the shield.


Mary said...

We are trying to get rid of the bermuda in our yard so we can plant buffalo grass. Most of it's gone because at one point we had agricultural termites that infested the yard and ate a bunch of the roots and leaves. Then we rototilled ineffectively. The guy we might hire for landscaping is planning on rototilling again and removing 30 tons of soil with the existing bermuda. That seems a little extreme and unnecessarily expensive.

However, I can see where the bermuda is starting to come back already, even in the front yard where we did a much better job tearing out all the roots with a rototiller.

Is the landscapers method going to even work? If the landscaper was able to get the irrigation put in by the end of April would I still be able to kill the bermuda with this method in time to plant the buffalo grass?

Lazy Gardens said...

The Bermuda grass has to be ACTIVELY GROWING before you can completely kill it with glyphosate.

Seriously - just read and follow the instructions for the repeated applications when the Bermuda is growing well. It is not a fast process, but the big mistake we made with the Buffalo grass was in not making sure the Bermuda was totally dead.


Where are you planting this lawn? We were constrained by having to have the plugs shipped in from Nebraska before it got too hot to ship. Now there are more distributors so it's not as big a problem.

Mary said...

We live in Tucson, so not far from Civano Nursery at all. The plugs aren't even available until April when the temps consistently stay above 65 at night.

Mary said...

Well, we decided to go ahead with our landscaper's plan and it's going well so far, although they are growing slowly. He replaced the soil with new stuff so there has been minimal weeding, but I still go out there every few days and pull some weeds. I have to be careful with the edges because we only had him do a part of the yard, the rest has the old soil with the bermuda remnants. He separated it with some plastic edging, but the bermuda has been loving the extra water it gets where the sprinkler water spills over a bit.

The bermuda in the yard has really perked up, so I'm going to start hitting it with the herbicide you mentioned. I need to do it soon because the bermuda is starting to get aggressive and sending runners over the plastic barrier and getting root.