The danger of turning them on this early is that anything above ground such as the backflow device might freeze and burst. The lines and heads are probably okay at this time. If you can drain the above ground parts after using them you might be okay but I wouldn't risk it. It's better to wait until at least mid April. Running a hose and sprinkler around would be your best bet for now.

Jeremy,

Hopefully, the guys who installed the sprinkler system for you, put in a quick and easy to access, method to turn off the main to the system, and then to drain out the water that's stored between there and the sprinkler valves, and in the backflow device. Assuming that's true, then you should be good to turn it on FOR A FEW HOURS ONLY, any time now. BUT... You MUST drain the water back out of the backflow valve etc. immediately after you finish watering.

If you don't do it right after the sprinklers finish, every time, then you will forget about it, and a couple days later you will wake up in the morning to the sound of running water. Like me, you will wonder who woke up early enough to already be in the shower. Then later when you wake again, you'll realize the water is still running. Then you'll lay there and wonder...just where is that water running? Sooner or later you'll discover you have a new 10 foot fountain in your front yard. And it has a great big pool underneath it. If you're particularly unlucky, the back flow device is right near the basement window well, and your basement is flooding.

Then, once you get the water turned off, you'll find out those 2 or 3 cute little plastic parts in that backflow device cost about 100 bucks if you buy and install them yourself, or I imagine twice that if you have someone else install them.

Actually, it was my buddy whose basement flooded, and had the fountain. My backflow is pretty far from the house, and both times I messed up and forgot to drain it, it didn't actually do a fountain it just leaked out enough water to make the yard really muddy for a few days.

Depending on weather and snow fall, I usually turn mine on, and water, and then drain it again several times each spring. I never turn it on and leave it on until Mother's Day, and even then, I keep a sharp eye on the weather, and I go cover up the back flow device with some thick blankets if we get a frost warning. Denver last frost is about the same as Fort Collins, so Mothers Day is probably a sensible date for you to go by also.

Bruce

Thanks for the input everyone. I'll probably just play it safe and wait until the first part of May, sounds like that is the smart move. Of course by that time my tomato plants will have been in the ground for weeks!

ion_source_guy, I was on board until you told me the horror story, which sounds like something that would happen to me. I do have easy access to everything, but I'd be afraid that I'd mess it up and not get it drained out properly.

Well, our Metro District just gave the landscape company the OK to turn the irrigation on, and no blow-out. Our system is 18" down and we'll drain the lowest head on each valve. My house I am still hand-watering and likely will turn on once in mid-April if the drought continues and the grass comes on...

Dan

I just couldn't wait any longer to turn the irrigation system on. Everything has been so dry and the high winds aren't helping much. It's not all that hard to drain the backflow device. Open the valve outide by the manifold and open the inside drain into a bucket. Hopefully I don't forget.

Look at those babies in action :-)