Roundup 15 SW lawn care, month by month
| Month | Tasks |
|---|---|
| January | Dormant — keep leaves cleared, stay off frozen turf |
| February | Dormant — keep leaves cleared, stay off frozen turf |
| March | Dormant — keep leaves cleared, stay off frozen turf |
| April | Dormant — keep leaves cleared, stay off frozen turf |
| May | Apply crabgrass pre-emergent · Light feeding after green-up |
| June | Light feeding after green-up |
| July | Aerate + overseed · Main fall feeding |
| August | Aerate + overseed · Main fall feeding · Winterizer feeding |
| September | Winterizer feeding · Final mow of the year |
| October | Dormant — keep leaves cleared, stay off frozen turf |
| November | Dormant — keep leaves cleared, stay off frozen turf |
| December | Dormant — keep leaves cleared, stay off frozen turf |
Reading the Roundup 15 SW lawn year
Roundup 15 SW runs on the classic northern rhythm: a short, important spring (pre-emergent before soil hits 55°F, one light feeding), a defensive summer (mow tall, water deep, feed nothing), and then the season that actually builds a lawn — early fall, when aeration, overseeding around Jul 17 – Aug 1, and the year's main feeding all land before the Sep 15 frost closes the year. With only ~116 frost-free days, the fall window is tight — miss it and the next real chance is spring.
Grasses that fit Roundup 15 SW
Frequently asked questions
When should I overseed my lawn in Roundup 15 SW?
For cool-season grass (bluegrass, fescue, ryegrass), overseed in early fall — in Roundup 15 SW that means roughly Jul 17 – Aug 1, timed 45–60 days before the average first fall frost (Sep 15) so seedlings establish before cold. Spring works as a backup but collides with crabgrass season.
When do I put down crabgrass preventer in Roundup 15 SW?
Aim for May 1 – May 22 — the estimated stretch when Roundup 15 SW soil approaches the ~55°F germination threshold, anchored to the average last frost (May 22). It's an estimate: a soil thermometer reading 50–55°F at 2″ depth for several days is the precise trigger, and pre-emergent must go down before crabgrass sprouts, not after.
When should I stop mowing in Roundup 15 SW?
Keep mowing as long as the grass grows — in Roundup 15 SW that's typically until Sep 8 – Sep 29, around the average first fall frost (Sep 15). Take the final cut slightly shorter to discourage snow mold.
What grass grows best in Roundup 15 SW?
Montana is cool-season country: Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue. See the grass guides linked below for identification and care.