I'm trying to expand a bed and found a metal pipe that's about 4 or 5 inches underground, and I was wondering if it would make a plant sitting close to it more susceptible to cold weather. Any thoughts?

No!

@cats1, I don't think an underground pipe would make a plant more susceptible to cold damage. In one of my daylily beds there is a heavy metal pipe that holds an old satellite dish for a clematis to grow on. The pipe is about 3 feet into the ground with daylilies and clematis growing all around it, I've never noticed any difference in their growth or a tendency to fail to survive our zone 4 winters even with the top portion exposed to lower temps than the underground section. I would be more concerned about what your pipe is for, water, sewer, gas...and if you want to be digging so close.

This is an image taken in early spring showing the pipe in the bed with the daylilies and the clematis that grows on it.

I agree with Char. I would be more concerned about what the pipe is there for. As a registered garden here in the state of Michigan, I am constantly getting warning letters from pipeline companies to always watch where I did so that I do not hit any pipelines. I am not a huge commercial daylily garden just a backyard gardener so those warnings really don't apply to me but I do know where are natural gas pipelines are and I avoid those. I think water pipes would be down too deep to really give you any trouble but I would worry about gas lines.

Thanks for the reply Char. Guess I'm kind of jumpy after seeing the plant losses from last winter. --And Hemlady, The pipe's a gas line... but the hole was carefully dug (knew it was there), and the plants near it will hopefully sit there alive and well for years. That's the plan anyway. I could just think of the plants as markers.

cats1 said:I could just think of the plants as markers.

That's what I thought, too, years ago when the satellite dish was actually being used for what it was intended. Can't begin to count the number of times I cut through the cable when I just had to move a plant....remember one particular time making an emergency call on a Sunday morning to the repair guy. Hubby was not impressed when I told him he was most likely going to miss his NASCAR race that day because "Guess what... I did it again". When they came out with the little dish it was mounted to the back of the hay barn with the wire running roof to roof with the house. No more in the ground wires

Oh no.

Char -- lol!

--We've been talking about it and think it might be telephone or electric instead of gas. Of the 3 I'd prefer telephone! Anyway we're still kicking it around.

I'm pretty sure if you call your utilities they'll come out and mark all your lines so you know where they are. They put little colored flags in the ground. I ran into a pipe when I was putting in a raised bed last year. Turns out it was an old drainage pipe that wasn't in use anymore. It was cast iron so I just broke it with a hammer & got rid of it. It beat having to find another spot for the bed when I'd already dug most of it already!

I put my 3X3X9' foot raised bed over the underground water pipes and the telephone and electricity conduits. I happily banged in steel supports into the ground too. It was only later I realised what I had done and nearly had a fit.