Question
I am in Santa Rosa, CA 95409 (zone 14 or 15, I believe) and I have a problem with my lawn jumping its bender board border and growing into adjacent planting areas. I have clay soil which gets pretty saturated. I have tried careful spraying of Roundup to kill off some of the growth in the planting areas, but this seems to lead to dead patches in the body of the lawn itself.I guess the Roundup is being carried through the root system from the outlying areas. What can I do? Thanks for any help you can offer.

Answer
Hi Ron Paris,

>>"...jumping its bender board border...?"

The ZIP code  95409 is in Horticultural Plant Hardiness zone 9.

You should only try to grow plants and grasses rated for zone-9.

 In regards to turf-grasses, there are several popular warm-climate grasses and most of these are 'stoloniferous'.  This means they will expand from a central crown to spread by stolons or  'runners'.  With a hardy grass-type like Bermuda grass, they can spread vigorously to invade areas where they are not welcome.

They can also spread under border materials, between tiny cracks and try to grow over small  barriers.  Usually, with weekly power edging (as with a recommended string-trimmer), you can keep invasive grasses well in check.  Having the best designed border installed is the best you can do to prevent the invasiveness when combined with regular zilching with a trimmer.  With a grass-type like Bermuda, the barrier height may need to be several (4+) inches into the ground and also rising above the grade several inches.

Broad-spectrum herbicides like ROUND-UP will kill virtually any non-woody herbaceous plant that gets a small dose, so you have to use it with care to avoid over-kill.  Do not spray on windy days to avoid having non-targeted areas affected.  Be sure your sprayer is not leaving a drip-trail, this will certainly cause dead-spots in the lawn.  You can also mix up this chemical in a smaller plastic bottle-type sprayer to give more control, or apply it with a small pain-brush from a container full to get greater precision of application.

Always use caution with lawn and garden chemicals. Note that weather conditions can be a critical factor in herbicide efficacy, so always check the weather reports before using these chemicals.

Some versions of ROUND-UP are said to be better at killing weeds 'roots and all'.  Using the old classic version which works entirely through the exposed green leaf may help to prevent any turf-grass losses in a perimeter of root-networking.

Depending upon your grass-type, you can also use herbicides that are less powerful than ROUND-UP.  Most lawn and garden centers will sell herbicides which target grassy-type weeds, and these chemicals may be more practical to control errant turf-grass invasiveness. You have to read the labels on these chemical products to know what to expect.  One good way to learn about them is to log onto the manufacturer's web-site for all the details to become an informed shopper.
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