How Often and When to Brush Hog a Field in Michigan: A Schedule by What the Field Is For
The Gibson Environmental Services crew
More than 10 years clearing land, cutting trails, and running forestry equipment in Southeast Michigan.
A Southeast Michigan field that is brush hogged once a year, in late summer or fall, stays a field: the saplings never get past knee height, the goldenrod and the grasses hold the ground, and the fence rows stay where the fence is. A field mowed twice, once in late June and once in late August, also beats the biennial weeds, because the first pass catches wild parsnip, thistle and knapweed between flower and seed and the second catches the late bolters. A field mowed every two or three years becomes shrubby wildlife cover on purpose. A field skipped for five years becomes a forestry mulching job.
That is the whole schedule in four sentences. The rest of this guide fills it in by what the field is for, pasture, hay, old field, food plot edge, fence row or wildlife cover, gives the mowing windows for the weeds that matter here, the cut heights, the difference between a first clearing and a maintenance pass, and a month-by-month calendar. It follows our guides to brush hog or bush hog and fall brush hogging, and the brush hogging service page covers the work itself.
The Schedule, by What the Field Is For
| Field | How often | When | Why |
|---|---|---|---|
| Pasture in use | Twice a year, more in a wet year | Late June after the first flush of weeds flowers; late August for the regrowth | Clipping keeps the grass vegetative and takes the weeds the animals refuse before they seed |
| Pasture being reclaimed | The first clearing, then twice a year | First pass in May or June once the ground is dry; sprout passes in August and the next June | Saplings and brush cut close to the ground sprout; two summers of passes run the roots out; see pasture reclamation |
| Hay field edges and headlands | With each cutting, plus one fall pass | June, July, August; October | The edges are where the parsnip and the thistle start |
| Old field kept open | Once a year | Late August to October | One pass takes the year's saplings and leaves the summer for the ground nesters and the pollinators |
| Wildlife cover (grouse, rabbit, deer bedding) | Every two to three years, a third of the field each year | Late winter or late summer | Shrubby regrowth is the cover; mowing in rotation keeps some of it at every age |
| Food plot edges and plot ground | Twice: a cleanup pass and a pre-planting pass | May and late July for a fall planting | See food plot clearing |
| Fence rows and lane edges | Once a year | Late summer or fall | Keeps the fence visible and the wire out of the brush; see overgrown fence lines |
| Retention basin and HOA common ground | Two or three times a year | June, August, October | See HOA and retention pond clearing |
| Field skipped five years or more | A forestry mulching pass first, then the schedule above | Dormant season for the mulching | Saplings past a few inches and brush you have to push through are mulcher work; see forestry mulching vs brush hogging |
The Weed Clock: Mow Between Flower and Seed
The extension weed scientists who have tested mowing all land on the same rule: it works when it lands between flowering and seed. For the biennials and annuals that reproduce only by seed, wild parsnip, poison hemlock, bull thistle, burdock, the knapweeds, a pass after the flower heads emerge and before the seed matures costs the plant its whole year; a pass too early just produces a second flower stalk from the base, and a pass too late spreads ripe seed. One Montana trial cut spotted knapweed density by most of its stand with a single mowing at flowering, repeated yearly. For the perennials that spread by root, Canada thistle, the mowing works by exhausting the root: a pass at bud stage, repeated each time the plant rebuds, with no single pass doing the job.
| Weed | Flowers | Mow | Repeat |
|---|---|---|---|
| Wild parsnip, poison hemlock | June to July | After the umbels emerge, before seed: late June into July | Late summer for the late bolters; low over the rosettes in fall; two or three years. See poison hemlock, wild parsnip and giant hogweed |
| Spotted knapweed | July to August | At first flower, mid-July to early August | Yearly; pulling in July helps |
| Bull thistle, burdock (biennials) | July to August | At flowering, before the seed heads fluff | Late summer |
| Canada thistle (perennial) | June to August | At bud stage, early June | Every time it rebuds, through the season, for several years |
| Goldenrod, asters (natives) | August to October | Leave them, or mow after frost | They are the field |
| Saplings: box elder, elm, ash, cherry, autumn olive | Any | Late summer, when the cut sprouts least | The next summer for the sprouts |
Cut Height
A brush hog cuts as close to the ground as the deck allows, which on our skid steer attachment means stumps cut as close to the ground as possible and the material chopped where it falls. On a pasture the pass is set to clip the weeds and leave the grass crowns, a few inches up. On an old field or a wildlife edge the pass is set higher, so the grass base and the cover of the ground nesters survive the summer. On a fence row or a lane the pass is as low as the ground lets it go. The height is set on the walk-through for what the field is for.
First Clearing vs Maintenance
The first pass over a field that has gone three to five years is a different job from the yearly pass that follows. The saplings are thick at the base, the brush is tangled with the grass, and every stump the cutter leaves sprouts the next summer; the first year is two passes and the second year is two, and by the third the field mows like a field. Past five years, when the saplings are past a few inches and the brush is something you push through, the first pass is a forestry mulcher pass, which grinds the stumps as well as the stems, and the brush hog takes over from the following summer. Both ride on the same machine, so the switch happens in one trip.
A Year on a Michigan Field
| Month | The field | The pass |
|---|---|---|
| March to April | Thawing, soft | None; walk it and flag what you keep |
| May | Drying on high ground | Reclamation first passes on dry ground; food plot cleanup |
| June | Growing fast; parsnip and thistle in bud and flower | Pasture clip; Canada thistle at bud; late June the biennials between flower and seed |
| July | Dry; knapweed flowering | Knapweed at first flower; the late biennials; food plot ground for an August planting |
| August | Hard ground; saplings full size | The sapling pass, when a cut sprouts least; second pasture clip |
| September to October | Goldenrod and asters; leaf-off beginning | The once-a-year pass for old fields, fence rows and lanes; see fall brush hogging |
| November | Firming, freezing | Last field passes; mulching season starts for the overgrown ground |
| December to February | Frozen | Wildlife-cover rotation cuts; the fields are done |
The 12-month clearing calendar puts the field passes next to the woodlot, fence row and invasive-plant timing for the same months.
Common Questions
How often should you brush hog a field?
Once a year keeps a field a field, in late summer or fall. Twice a year, late June and late August, also beats the biennial weeds. Every two or three years grows wildlife cover on purpose. A field skipped five years is a forestry mulching job first.
When is the best time to brush hog a field?
Late June for the weeds, between flower and seed; late August for the saplings and the regrowth, when a cut sprouts least; September or October for the once-a-year pass on an old field or a fence row. Spring is for walking it, once the ground has dried.
How tall can grass and brush be before brush hogging?
A rotary cutter handles grass and weeds of any height and saplings up to the diameter the cutter is rated for, around an inch for light-duty models and a few inches for the heavy ones. Past that, and brush you have to push through, is forestry mulcher work, and both attachments ride on the same machine.
How high should a brush hog be set?
For a pasture, a few inches, to clip the weeds and leave the grass crowns. For an old field or a wildlife edge, higher, so the grass base and the cover survive. For a fence row or a lane, as low as the ground allows. The height is set for what the field is for.
Can you brush hog a wet field?
A tracked skid steer crosses damp ground a wheeled machine sinks in, and a wet field in June gets its pass once the top dries. Standing water and the spring thaw are the two conditions to wait out; frozen ground in winter carries the machine fine.
What if the field has saplings in it?
Saplings cut close to the ground sprout the next summer, so the first year is two passes and the second year is two, and by the third the field mows like a field. Saplings past a few inches are ground stump and all by the forestry mulcher first, which removes the sprouting problem.
Do you do yearly field mowing?
Yes, as scheduled brush hogging: a pass or two a year set to the use of the field, with the weed windows on the calendar and the first clearing done by mulcher where the field has gone too far for the cutter. See the brush hogging and property maintenance pages.
Sources and Further Reading
The mowing-window rule and the weed timing come from these extension pages; the naming and sizing of rotary cutters from the Cornell small-farms program. Our own schedule and cut heights are stated in the text.
Iowa State University Extension and Outreach: Mowing requires management to be effective
Iowa State University Extension and Outreach: Weed control in pastures: a window of opportunity
Montana State University Extension: Mowing to Manage Noxious Weeds (MT200104AG)
Mississippi State University Extension: Making pasture weed control decisions
Cornell Small Farms Program, Cornell University: Brush Hogs and Rotary Cutters: Multi-purpose Tools for the Small Farm
Where We Do This Work
The work in this guide is done across eight Southeast Michigan counties from our base in Royal Oak. Every county page lists the townships we work in most, with a page for each.
Want the Field on a Schedule?
Tell us what it is for and we put the passes on the calendar, with the weed windows where they belong. The quote is free.