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oxalis

Q: I am not sure what I have in my lawn, but it is taking over and nothing is helping to get rid of it. Hope you can help.

Q: I am not sure what I have in my lawn, but it is taking over and nothing is helping to get rid of it. The leaves are similar to clover. It has a root that looks like a white radish and blooms are purple. It has spread all over and is in large clumps choking out my grass. I pull all I can each year, but it is more than I can handle now. I live in Fernandina Beach. Hope you can help.
A: The weed you have is in the family oxalis, which if placed in a pot is often called shamrock.  The flowers may be white, purple or yellow. The petals often resemble clover which causes people to confuse this plant with a common variety of clover. This particular lawn weed is difficult to control because it is classified as a perennial.

Unlike annual weeds, which only reproduce by seed, perennials can reproduce by seed and vegetatively using other parts of the plant like the root, stolen or leaf. Pulling weeds by hand, which is my favorite pastime, often is unsuccessful with perennials because of their ability to reproduce in a variety of methods. Any portion of the weed left in the ground can produce a new plant, hence the reason why some weeds seem to be so stubborn and continue to return year after year. You will need to be persistent with this weed and consider using a weed killer for broadleaf weeds but be sure the product can be used on your type of grass. In addition, you should spot treat only the areas where the weeds exist, avoid spreading the product over the whole lawn.

One other thing to consider is why weeds are coming up in your lawn. Healthy turfgrass should allow few weeds the opportunity to grow. If your turfgrass is St. Augustine remember to water it once every 5-7 days in the summer and once every 10-14 days in the winter. Water the lawn in the morning hours between 6am and 10am. Use a fertilizer product similar to 15-0-15. Look closely at the label and try to find a fertilizer product that has a portion of the nitrogen as slow release nitrogen. The first and last numbers on the label, which stand for nitrogen and potassium, should be balanced meaning the ratio should be 1:1 or at the most 2:1. Mow the lawn at the highest height. Fertilize in March and August or September. Avoid using weed and feed products. Use an iron sulfate product that contains only small amounts of nitrogen during the summer months.