A quick note before we start: PeakGreen doesn't perform sprinkler blowouts ourselves — irrigation work requires its own licensing and equipment. But it's one of the most common questions we get every fall, since it usually comes up in the same conversation as aeration, leaf cleanup, and snow removal. So here's the full picture: why it matters, when to schedule it, what the process actually involves, and how to tell a rushed job from a proper one.
Why This Can't Be Skipped
An in-ground irrigation system is a network of pipes, valves, and a backflow preventer sitting a few inches to a couple feet below the surface, with sprinkler heads at ground level. Minnesota's frost line runs deep — commonly cited around 60 inches for foundation design purposes, though actual freeze depth varies by winter — which means water left inside those lines will freeze at some point in a normal Minnesota winter. Water expands about 9% as it freezes, and PVC pipe, copper fittings, valves, and the backflow preventer all lose that fight. The backflow preventer, which usually sits above ground or in a shallow box, is typically the first and most expensive casualty.
What a skipped blowout costs. A cracked backflow preventer alone commonly runs several hundred dollars to replace, before factoring in any split underground lateral lines, which are more disruptive and expensive to find and repair. A blowout is a small, predictable cost. Skipping it is a gamble against a Minnesota winter — one the winter usually wins eventually.
When to Schedule It
The goal is to get the system blown out before the first hard freeze, not right at the calendar's first frost warning. In southern Minnesota, irrigation contractors typically start scheduling blowouts in late September and work through most of October, aiming to finish before overnight lows are routinely dropping into the low-to-mid 20s.
One extra run of the system on an unseasonably warm November day isn't worth the risk of a frozen line the following week. Once it's blown out, leave it off for the season.
How a Blowout Actually Works
Shut off the water supply
The main water line feeding the irrigation system is closed at the shutoff valve, isolating the system from the house's water supply.
Connect an air compressor
A compressor is attached at the system's blowout port, sized correctly for the pipe diameter and system layout — this is the step where DIY attempts most often go wrong.
Run each zone, one at a time
Compressed air pushes remaining water out through the sprinkler heads, zone by zone, until each one is running clear air with no water spray.
Drain the backflow preventer
The backflow device and any low points in the system are manually drained, since trapped water here is one of the most common freeze failures.
DIY vs. Hiring a Pro
DIY Blowout
Professional Blowout
If you go the DIY route, use the lowest effective PSI the manufacturer or your system's documentation recommends, never exceed it, and never stand over a sprinkler head while air is running through the line. If you're not confident about your system's specs, that uncertainty alone is a good reason to call a pro.
Finding a Qualified Irrigation Contractor
A few things worth asking before you book:
- Do they carry backflow-testing or irrigation licensing? Requirements vary, but a contractor who works on irrigation regularly should be able to speak to this without hesitation.
- What size compressor do they use, and do they check zone by zone? A rushed blowout that doesn't verify every zone is running clear can leave water trapped in one section.
- Do they inspect the backflow preventer and heads while they're there? A good blowout appointment catches small problems — a cracked head, a leaking valve — while the system is already open, instead of leaving them for a surprise in spring.
Typical blowout appointments are quick, and pricing generally scales with the number of zones on your system — it's worth getting a specific quote for your setup rather than assuming a flat rate applies. This falls outside what we handle directly, so we'd point you toward a local licensed irrigation contractor for the appointment itself.
Where PeakGreen fits in. While your irrigation contractor is handling the blowout, it's a good time to line up the rest of your fall lawn work — aeration and overseeding, fall fertilization, leaf cleanup, and a snow removal plan for winter. We handle all of that across Owatonna, Austin, Rochester, and southern Minnesota.
Get the rest of your fall lawn care handled.
Aeration, overseeding, fall fertilization, leaf cleanup, and snow removal — while your irrigation contractor handles the blowout.
Call 507-440-7823