The arrival of spring signals the end of winter dormancy and the beginning of the annual growth cycle for turfgrass. Proper lawn care during this period is an important factor in establishing a dense, healthy stand of grass for the rest of the year. Mowing height plays a significant role in how the grass recovers from the cold season and prepares for summer heat and stress. The strategy for the first few cuts in spring differs considerably from the maintenance approach used during the peak summer months.
When to Start Mowing and Pre-Cut Preparation
Timing the first mow correctly requires observing both the calendar and the environment. The turf should be actively growing, which often occurs once the soil temperature consistently reaches between 40 and 50 degrees Fahrenheit. Cutting the grass before it has fully emerged from dormancy can stress the plant’s stored energy reserves.
Before the mower is engaged, prepare the lawn surface. Winter often leaves behind debris, such as fallen sticks, small stones, or matted leaves, which should be cleared to prevent damage to the mower blades. A thorough raking can also help stand up matted grass blades and break up turf damage, like snow mold.
Addressing surface issues early helps ensure a uniform cut and promotes better air circulation. This preparatory step allows for a final inspection of the lawn to identify any areas needing immediate repair before the growing season fully commences.
Setting the Deck for the Very First Cut
The initial pass with the lawnmower requires a specific height setting that differs from the ongoing spring maintenance level. For this first cut, it is recommended to set the mower deck slightly lower—about 0.5 inches shorter—than the height used for the rest of the season. This must be done carefully to avoid scalping the turf.
The purpose of this shorter cut is to remove accumulated dead, brown leaf tissue from the previous season. Removing this dormant growth stimulates the grass plant to begin producing new, green blades and encourages lateral spreading. This is especially helpful for turf varieties that spread via rhizomes or stolons, leading to a denser lawn.
To determine the cutting height, measure the existing length of the grass blades and calculate the desired removal. For example, if the lawn is currently four inches tall, the first cut might target a final height of three inches. This first session sets the stage for the health and vigor of the new growth flush.
Maintaining Height with the One-Third Rule
After the initial cleanup cut, all subsequent mowing throughout the spring must strictly adhere to the established one-third rule. This guideline states that you should never remove more than one-third of the total height of the grass blade in a single mowing event. Following this rule prevents the grass from going into shock, which occurs when too much photosynthetic area is removed at once.
Removing excessive leaf tissue forces the plant to draw heavily on stored carbohydrates to regrow the missing blades, diverting energy away from root development. Consistent application of the one-third rule encourages the plant to develop deeper, more resilient root systems, which are better equipped to handle summer drought conditions. When the grass is consistently cut at a higher level, deeper root growth is naturally promoted because root length is proportional to leaf length.
An example application of this rule is simple: if the preferred height for the lawn is three inches, the grass should be mowed before it reaches four and a half inches. Cutting at this level ensures that only one and a half inches (one-third of the current height) are removed, leaving the plant with sufficient leaf area for efficient photosynthesis. This slightly higher cut also provides natural shade to the soil, which helps suppress weed seed germination and minimizes water evaporation.
How Grass Species Affect Spring Length
The correct spring mowing height is dictated by the type of turfgrass present in the lawn. Grasses are broadly categorized into cool-season and warm-season varieties, and each group has distinct requirements for optimal leaf length.
Cool-season grasses, which include Kentucky Bluegrass, Tall Fescue, and Perennial Ryegrass, generally prefer a higher cut in the spring. These varieties benefit from a finished spring height typically ranging between three and four inches. The increased leaf surface area allows for maximum photosynthesis during the cooler spring weather, building up energy reserves before the summer heat arrives. Cutting these grasses too short can weaken them, making them susceptible to disease and thinning out the turf.
Conversely, warm-season grasses like Bermuda, Zoysia, and St. Augustine prefer a much shorter spring cut. These grasses thrive in heat and are usually maintained at heights between one and two-and-a-half inches. The shorter height helps them transition out of dormancy and encourages denser lateral growth. Understanding the species is necessary for setting the final ongoing maintenance height for the spring season.