Question: I've heard that pouring beer on my lawn will help it stay green. Is this true? If so, how should I put it on and what type is best?

Answer: The idea of pouring beer on lawns has roots in the myth that, since beer makes some people happy, it will make grass happy. This is not true - research has not shown any benefits from applications of beer, green or otherwise. The amount of (dead) yeast in beer will not provide nitrogen to help grass grow, it will not promote organisms to break down thatch, and the carbohydrates, or sugars, will not be used by grass as a source of food. Beer is mostly water, which the lawn can receive from irrigation.

Q: I've noticed that weeds are already growing in my lawn. Every year I have problems with one that looks like a shamrock but is very difficult to get rid of. What is it and how can I control it?

A: Two weeds commonly found in lawns could be the culprit.

Yellow wood sorrel (Oxalis stricta) grows in moist, fertile soils with thin grass cover. It has small yellow flowers and shamrock-shaped, purplish leaves that fold up at night or on overcast days. Should you have yellow wood sorrel, check to see whether there's too much water on the lawn. This may be due to poor drainage or too-frequent irrigation. Ideally, lawns should be allowed to dry slightly between waterings.

White clover (Trifolium repens), with its white, ball-shaped flowers and shamrock leaves, is another common weed, but it thrives in moist, infertile soil. Infertile soil is typically short on nitrogen and can be corrected by applications of good-quality fertilizer. Since this weed also thrives in moist soils, check the amount of water being applied to the lawn and make adjustments as necessary throughout the growing season.

Carol O'Meara is the Colorado State University Cooperative Extension horticulture entomologist and Colorado master-gardener coordinator in Boulder County. Visit www.planttalk.org.