Whether you’re an expert agronomist or you have just recently been introduced to the world of lawn care, diagnosing problems in turfgrass can be particularly challenging. Vegetables, flowers, trees, shrubs, etc., are larger and they have a variety of plant parts that may provide more obvious clues when issues need to be diagnosed. Grass, however, tends to be more discreet when it’s unhealthy. Visual symptoms can be nearly identical across a spectrum of issues including nutrient deficiencies, diseases, insects, and environmental problems. Furthermore, these limiting factors can be intertwined with one exacerbating another. In many cases, the catalyst for susceptibility to other problems is lackluster nutrition. Here are four tell-tale symptoms to look for that may point to a nutrient deficiency in your lawn.
Pale Green or Chlorotic Leaves
Pale green blades of grass are arguably the most common and obvious indicator of a nutrient deficiency. Nitrogen and sulfur are two macronutrients that cause blades of grass to show a pale green color in comparison to the rest of the lawn. This can occur in patches, or can be diffused throughout the entire lawn. As these symptoms progress, they lead to chlorosis, or yellowing, of a significant portion of the leaf. Chlorosis, sometimes to the point of whitening, can also be an indicator of a wider range of nutrient deficiencies like iron, potassium, zinc, manganese, or copper. Before jumping to conclusions about these off-colored leaves, be sure that the lawn isn’t too dry or too wet, as these nutrients may be in the soil but unavailable for uptake due to an imbalance of water.
Before discussing purple leaves, note that this doesn’t apply to newly seeded grass as many varieties of grass seedlings display a purple color. However, if your mature grass starts to show a hue like a Minnesota Vikings helmet, you may want to consider checking your soil phosphorus levels. As plants become starved of critical phosphates, they begin to accumulate a reddish-colored pigment in their leaves called anthocyanin. While this may initially color your lawn a darker green than normal, the leaves will begin to display a purple color as this pigment accumulates. Purple leaves can also be a result of cold damage, but if environmental conditions are conducive for healthy grass and leaves begin turning purple, it may be time for a phosphorus fertilizer.
This may seem a bit obvious, but if your lawn, or areas of the lawn, aren’t growing as they should be, then the grass may be hungry. This can often be the first symptom of nutrient deficiency that is noticed prior to discoloration of the leaf. Nutrients like phosphorus and calcium are essential for root growth, so a lack of these minerals can lead to stunted roots and overall reduced vigor. Nitrogen and iron are nutrients that play major roles in the growth of plants, so their absence leads to a decrease in food production. If you observe areas of grass that just aren’t growing like they should be, a deeper investigation is likely necessary
Stripes on your grass leaves, or interveinal chlorosis, is a more obvious indicator of a nutrient deficiency as it's not a symptom displayed by other issues, like disease. Interveinal chlorosis shows itself as yellowing between the veins of the leaf while the veins themselves remain green. Iron is commonly recognized as the most frequently deficient nutrient in turfgrass, and interveinal chlorosis is one of the first indicators of iron deficiency. It may also be evident with manganese and later stages of magnesium deficiencies.
Soil testing your lawn at a minimum of every three years is an important step in managing your soil nutrition. It will enable you to track trends and develop management plans while identifying specific nutrients that need to be added. When soil testing, it’s recommended that you take several samples throughout the lawn and mix them well so that you’re able to get a full picture. However, if you notice any of the above symptoms in specific areas, it’s recommended that you take isolated samples from those areas so that you can accurately identify, and possibly rule out, a nutrient deficiency as the cause of the problem.