Hay, which is dried forage, serves as a significant feed source for livestock. The timing of its harvest directly impacts its nutritional value and overall quality. The “hay season” is a flexible window determined by plant biology and environmental conditions, not a fixed calendar date. The decision to cut hay balances the goal of maximizing yield with the need to achieve peak nutrient content for the animals.
Primary Factors Determining the Ideal Cutting Time
The stage of plant maturity is the most important factor influencing the decision to begin hay cutting, as it determines the trade-off between quantity and quality. For cool-season grasses like timothy or orchardgrass, the target is the late boot stage—just before the seed head emerges—which offers a good balance of high protein and acceptable yield. Legumes like alfalfa are typically harvested at the late bud to early bloom stage, meaning no more than 10% of the plants should be flowering. Delaying the cut past these stages allows for greater tonnage but results in a rapid decline in digestible nutrients.
Another factor is the moisture content of the hay, which must be reduced significantly for safe storage and baling. Freshly cut forage can be as high as 80% moisture, but it must dry down to a range of 15% to 20% before baling. Baling hay above 20% moisture promotes mold growth, excessive heat generation, and potentially spontaneous combustion. Conversely, hay below 15% moisture becomes brittle, leading to excessive leaf shatter and loss of the most nutritious parts of the plant.
Weather conditions are paramount, requiring a forecast of several consecutive days of dry, sunny weather with low humidity following the cut. The initial drying process, known as curing, relies on sunlight and air movement to rapidly reduce moisture. Plants continue to respire after cutting, consuming valuable carbohydrates until their moisture content drops below approximately 40%. To maximize drying time and minimize this nutrient loss, many producers aim to cut the hay in the mid-to-late morning after the dew has evaporated.
Geographic Differences and Multiple Cuttings
The hay cutting season’s start and end dates depend on the local climate and latitude, leading to significant geographic variations in harvest schedules. In warmer regions, such as the Southern United States, the first cutting may begin as early as mid-May. Moving north into areas like the Northern U.S. or parts of Canada, the season starts later, often closer to late May or early June. This difference in the length of the growing season dictates the number of harvests possible each year.
The first cutting is typically the heaviest in yield because of the abundant moisture and growth that occurs during the spring. However, this initial crop often has lower quality due to rapid growth and unpredictable weather that can delay harvest until the plants are more mature. In the coldest northern areas, a field may only produce one or two cuttings annually.
Subsequent cuttings (second, third, or fourth) are possible in regions with a longer growing season. These later harvests rely on the plant’s regrowth, which requires 30 to 45 days between cuttings. Although the yield from these later cuts is usually lower, the quality is often higher because stable weather allows for a more timely harvest at the optimal maturity stage. For instance, alfalfa fields in warm climates with irrigation may produce four or more cuttings, which tend to be finer and higher in protein.
How Cutting Stage Affects Hay Nutritional Value
The maturity stage at which hay is cut directly determines its nutritional profile, primarily by influencing the plant’s fiber and protein content. Forage quality declines rapidly as a plant matures and shifts from the vegetative to the reproductive phase. This maturation process increases the proportion of stems and decreases the proportion of leaves, which contain the majority of the plant’s protein and digestible nutrients.
Cutting the forage too early results in hay that is high in protein and highly digestible, but the overall yield is low. Delaying the cut increases the total volume of hay but significantly reduces its feeding value. This late-cut hay has a higher concentration of fiber components, specifically Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF), which are harder for livestock to digest. High NDF levels indicate an animal will eat less of the hay, while high ADF levels signal lower overall digestibility.
Nutritionists use metrics like Relative Feed Value (RFV) to combine the effects of NDF and ADF into a single number that estimates hay quality. High-quality hay, cut at the pre-bloom stage, will have a higher RFV, making it suitable for high-demand animals like young or lactating livestock. The producer must manage the balance where nutrient quality is still high before the yield becomes too low to be economically viable.