Question: I read your article about Bermuda grass and have a question concerning the condo development where we live. The complex includes a large area of grass and mesquite trees. The HOA overseeds in the winter. This makes for a beautiful green area and also greatly cuts down on blowing dust. The landscaping company has advised the HOA to not overseed every three years to help the Bermuda grass. Does this make sense to you? I see many places (e.g. golf courses) that overseed every year and the Bermuda grass appears to come in just fine.

Answer: Yes, it makes sense. Continuous overseeding can cause stress to Bermuda grass if proper care is not taken for proper overseeding timing/preparation and proper spring transition back to healthy Bermuda grass conditions. Rye grass is a common cool season grass used to overseed Bermuda grass in the fall. Extended rye grass seasons on the front end from early overseeding and well beyond spring transition into summer will weaken the root system and reproductive capabilities of Bermuda grass. If these unhealthy practices are repeated annually, exhausted and stressed Bermuda grass diminishes over time and requires renovation. Thus, skipping overseeding every few years can provide the Bermuda grass a nice long growing season from March to November to rebuild roots. If the stress is minimized by best management practices and a good 100 days of optimal growing conditions are provided each year, Bermuda grass can be overseeded regularly. The minimum 100 days should be in the June through September timeframe. For more details on the timing and preparation, there is a nice publication available online by the University of Arizona turf grass specialists, David Kopec and Kai Umeda.

Question: I have researched and talked to many people about how to kill Bermuda grass most effectively while being as environmentally friendly as you can be. I have heard of several different methods, including covering the whole area in plastic as well as using Roundup as possible methods. I would like your opinion on the best method to use to kill Bermuda grass. My understanding is the only chemical way to do it would be with Roundup, but my wife is very against that idea. I have read the research on the biochemical makeup of Roundup and I am not sure if it is truly toxic if you only use that one to two times.

Answer: Roundup or any other product containing the active ingredient glyphosate is the most effective and least labor-intensive way to manage/kill Bermuda grass and many other weeds. It does require repeat applications and the grass needs to be green when you spray to be most effective. Other methods include scraping off the top layer of grass and covering it with landscape fabric, clear plastic, or cardboard, and digging the grass up with a shovel. You can certainly kill much of the grass through solarization, starvation, or digging it up. The problem, as you may know, is the roots, or parts of them, are still alive in the soil in many cases with all of these methods. They will eventually find a way around or through the covers so it may be more labor intensive to manage it. Bermuda grass spreads by underground stems (rhizomes) and aboveground runners (stolons), not to mention seed. A systemic herbicide can get to the root of the problem with less effort. No matter which method you choose, if you live in an area with unmanaged Bermuda grass nearby, it will eventually return so you need to remain vigilant in your management. Regarding the toxicity, according to the Monsanto label, glyphosate is a moderate irritant if eyes and skin are exposed but is practically nontoxic otherwise unless you are an aquatic organism. As always, it is best to follow the instructions on the label of any pesticide to avoid harming any non-target organisms.

Question: Recently we purchased pansies at Wal-Mart. They immediately wilted. I know they like to be in bright sun and so I placed them in an environment similar to what they were at Wal-Mart. Any suggestions to thrive? I’ve watered them when the soil is dry to touch and haven’t replanted them. Would like to think I have a green thumb. Probably not.

Answer: Pansies and violets (Viola species) are great for adding color to your landscape in the winter and spring. In general, they can be planted in sun (as long as it’s not too hot) or partial shade although some species prefer variations on this rule of thumb. If you look at a climate zone map, you might notice that it appears to be too hot for them in the Tucson area in the summer. They will look bad once the weather warms to their limit so we can treat them like annuals and replace them with something else. They also need water twice a day for the first couple weeks when they are getting established. This may be why yours wilted.


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Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions and photos may be emailed to tucsongardensage@gmail.com