Hi Jon and thanks for your question about physical ways to kill weeds. In the Portland area, both methods could be used, depending on the specific weed management goals and the types of weeds present. Solarization is more effective for killing existing weeds, while occultation is more effective for preventing weed germination. It's important to consider the specific weeds you're dealing with and the conditions in your yard, such as the type of soil and the amount of sunlight, when deciding which method to use.

If you're looking to kill existing weeds, solarization might be a better option, as it can effectively kill weeds by preventing photosynthesis. However, if you're looking to prevent weed germination, occultation might be a better choice, as it can suppress weed growth for an extended period of time.

Please note that while both methods are effective, they may not completely eliminate all weeds, and additional management practices such as hand-pulling or chemical control may be necessary for complete weed control. It's also important to consider the potential impact of these methods on beneficial soil organisms, as solarization can kill many soil pests but may also affect beneficial organisms.

I prefer occultation with a thick layer of arborist chips. This benefits the soil over time, makes weeds that do come up easier to pull and is a free way to help arborists dispose of their chips.
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