Wood Chips, Mexican Primrose and Bugs

Q. I was overrun with Mexican primrose but have completed all my weeding.  I am thinking about putting wood chips around my roses to keep the weeds from returning.  Is this a good mulch for the roses? Or might it attract ants or insects I don't want? 

Mexican Primrose is a pretty ground covered the first year but it starts to get a little scraggly in the following years. It looks like it would be easy to control with weed killers. It's not.

A. Mexican primrose is very difficult to get rid of once it gets established. Many weed killers won’t touch it. An effective control technique is to keep removing the top of the plant as soon as it pops up. It takes lots of repetition and plenty of diligence but it works.

            Remove the tops by cutting them back with a hoe. Some weed control chemicals “burn” it back and are essentially chemical “hoers”. The basic idea is to let the plant invest it’s energy into growing new, young tops and then remove the tops after they get only a couple of inches tall. This constant removal of the tops exhausts the energy supply stored in the roots and the plant eventually “gives up”.

This is where bugs like to hang out in landscapes. They like water and irrigation boxes are where they can usually find plenty of it. The other thing they do is try to crawl into the house when it gets cold. A foundation spray of an effective insecticide applied in the fall when temperatures cool off and using that same spray in irrigation boxes usually keeps them at bay.

            Woodchips are a great mulch for roses, combined with an application of compost on the soil surface underneath the woodchips. In my experience, the woodchips are no worse than rock mulch or gravel applied to the soil surface regarding attracting insects.

            Insects like to “hang out” in irrigation boxes where there is water. Spraying the inside of the irrigation boxes with an appropriate pesticide every couple of months usually takes care of this problem.