The Start of Grazing Season

How tall should the grass be before you start grazing in the spring?

The majority of publications you may have read will suggest starting to graze your pasture when the grass is, depending on the grass species, about six to eight inches tall. That is true for set-stock grazing operations, meaning you do not intend to rotate or do not intend to rotate frequently in a meaningful way between grazing cells.

Rotational grazing allows but also requires a different approach. If you were to heed the same advice and wait before the pasture grasses measure six to eight inches, you would have to wait until sometime mid-May in most parts of the Northeast and New England. You then would have little time left before much of the pasture becomes unpalatable because the developing seed stems are high in lignin. Yet, your pasture rotation will last a total of several weeks. By the time you have grazed every pasture cell you will have wasted a lot of pasture plants, which have become too mature and less nutritious.

Starting a strict daily rotation on April 14th in 2022. Ulf Kintzel / White Clover Sheep Farm

The height of six to eight inches of pasture grasses is being suggested in publications so that the plants are not weakened or even killed when grazed. That is a high risk when grazing early without any frequent pasture rotation. However, in a rotational grazing system, any forage in any given grazing cell will have many weeks to recover and regrow after being grazed. During the main grazing season of late spring and throughout the summer pasture rest should be between five and six weeks. It can be a week or two less in the beginning of and up to mid spring, and it can be a week or two more towards late season to allow for stockpiling.

In a rotational grazing system, how short can the grass be when you start grazing without doing any long-term damage to the pasture? When the growing season starts in April and into May, all forage species are primed to grow. Pasture is very “forgiving” at that time. It is more sensitive to shorter rest periods and short grazing in the summer, and it is quite sensitive to it in the fall. However, the rigorous growth in the spring allows for a turnout as soon as it greens up. No need to measure the length of the grass! In fact, I turn out my sheep just as soon as there is a green sheen to the pasture. I don’t practice rotational grazing at that point in time. The flock has access to all my pasture. I feed supplemental free-choice hay in hayfeeders in the pasture for as long as they will eat it. When the weather turns bad, the flock goes in the barn and feeds on hay until the weather returns to being nice again that young lambs can spend time outside.

The pasture is at the beginning of spring the most potent when it comes to nutrients. Both protein and energy levels are very high. In addition, the energy in the plants comes in its most valuable form: sugars. Any potential lack in fiber is being countered with the available hay. It is very important when you have ewes that nurse young lambs to have very nutritional feed. Any stored feed like hay or baleage does not come close to matching the nutrient content of pasture in early spring.

As the grass starts growing more vigorously in late April, I start setting up rather large grazing cells and start a daily rotation. The large size at this point in time is simply due to the fact that there isn’t much forage per acre available yet. As the growth of pasture accelerates, I make my daily grazing cells smaller and smaller. The hay is being provided until the sheep stop eating it in any significant amounts. Sometime in mid-May the pasture that will be hayed is set aside also and will not be grazed anymore.

You may have noticed, I described a rather vague timeline for the months of April and May. The vagueness is on purpose because every year is different and the decision about the size of the grazing cells, when to stop hay feeding, and when to set the fields aside that will be hayed depends on the weather during spring. Warm weather and especially warm rain can speed up the growth of pasture, dry weather and a cold snap can delay it significantly. Besides, you, the readers, may live in an area with a slightly different climate even though geographically speaking, many of you are not that far away from me. Observing the weather and monitoring the growth of pasture will be necessary to assess the daily course of action.

Just as soon the grass starts greening up, I start grazing. Ulf Kintzel / White Clover Sheep Farm

Is there a risk of damaging or weakening the pasture plants when grazing so early in the season? A field trial conducted in Wisconsin with heifers examined exactly that. The result of that trial was that there is no significant decrease in yield when pasture is grazed early just as long as a proper rotational grazing schedule was observed later on and throughout the grazing season. That has been my experience as well.

The argument against early grazing has been made in discussions with me that “no significant decrease in yield” may still mean there is some decrease in yield. Let’s assume for this discussion’s sake that this is true. Let’s assume someone who doesn’t want any decrease in yield and therefore starts grazing when the grass reaches the height of six to eight inches. That is in any given year approximately a month later than when I start grazing. That month the flock needs to continue feeding on stored feed and possibly grain if your flock is not grass-fed. Feeding stored feed is the single biggest expense for most sheep farms. I save that cost almost entirely.

In addition, delaying grazing most definitely will mean that a lot of pasture will have become in part unpalatable by the time the first grazing cycle of a rotational grazing system nears its end because you are now almost certainly in the month of June. Furthermore, early grazing has the advantages of reducing the number and size of seed stems, which will keep lush vegetative undergrowth growing for a longer time and thus it will keep the pasture more palatable. It also allows the individual plants of grass to develop more tillers. Weeds are grazed more aggressively early in the season, reducing the amount of competition for grasses and legumes.

If there is an insignificant decrease in yield later during the summer because of early grazing, I have never noticed because throughout the grazing season I have ample pasture available due to a rigorous daily pasture shift, ample rest time, leaving appropriate residual, and other good pasture management practices. Early grazing has been good for the profitability of my sheep enterprise without any measurable downside.