Tied up in knots

March 10, 2023 8:09 AM

What is the appropriate knot to use in this situation?

I need to hang some grow lights and adjust their height over my seedlings as they grow. I have some sturdy cord I intend to use to hang the lights, which I will loop over a bar. What is the correct type of knot to use with this setup so that I can easily adjust the height without untying and retying the knots? I imagine there's some sort of locking slip knot available that should be the right way to go about this.

posted by backseatpilot to Home & Garden (12 answers total)

I would use a clove hitch, which can be loosened and adjusted. A girth hitch would be another alternative.
posted by Dashy at 8:13 AM on March 10, 2023

Clove hitch is the correct answer here. It's used in alpine climbing to clip into anchors and lets the climber adjust their distance from the anchor but holds under tension.
posted by Special Agent Dale Cooper at 8:18 AM on March 10, 2023

Clove hitch is a good answer but not always the best, depending on your specific geometry, size and material of cordage, and aesthetics. For example, clove hitch wouldn't be a great choice if you were using monofilament fishing line for an invisible look, because it could just slip out under enough load.

There's a whole family of adjustable hitches that have similar functions but offer a variety of subtle differences that can make one better than others for certain applications.

A few alternatives that may work better for you are the adjustable grip hitch, the taut-line hitch, and the Farrimond friction hitch.
posted by SaltySalticid at 8:46 AM on March 10, 2023

Blake's hitch, or anything from the slide and grip section of that knot site.

Tie to the light, loop over the bar, hitch to itself. You might prefer a prusik or something, but the idea is good and Blake's hitch is just so fun. Once it's tied, just pinch it and slide it as tight as you'd like, then let go and it grips!
posted by Acari at 8:47 AM on March 10, 2023

A midshipman's hitch (a.k.a. a taut-line hitch) is great for adjustable-length loops that should be under tension. Make the loop you hang over the bar with one and then you can lengthen or shorten the rope by changing how much material is in the loop.
posted by jackbishop at 9:04 AM on March 10, 2023

(I use a spring clip on the cord, which is easy to operate one-handed while adjusting the height of the lights.)
posted by away for regrooving at 9:42 AM on March 10, 2023

In case you don't want to get tied up in knots or have issues with the rope slipping and / or you don't want to risk having the lights come crashing into the plants as you adjust the height, it may be easier to pickup a rope ratchet or cam ($12 for a 4 pack). Most grow lights come with them in the box.

Alternatively, you may be able to attach a cleat off to the side. The rope just loops over the upper pipe that the lights are hung from and then over to the cleat. Secure it with two or three wraps in a figure 8 and then a quick half hitch to secure it.
posted by SegFaultCoreDump at 9:46 AM on March 10, 2023

I'd bring the end back to it self and tie it on with an asymmetrical prusik knot. A prusik knot will slip when you relieve tension but other wise hold tight and you wouldn't need to re tie until you reached the limits of the loop size.
posted by Mitheral at 10:16 AM on March 10, 2023

Personally I use jack chain for this, not cord. I bend an end link open a little to make a hook, then attach the chain to the light fitting two or three links from that end so that the hook is hanging off a very short length of chain. The long end gets looped up and over the support bar, then comes back down to the fitting so the short end can hook into one of its links.

Adjusting the height is then done by pulling down on the long end to raise the fitting a little and take the tension off the hook, which can then be easily unclipped from its present link and clipped back into another once a suitable height is achieved.

This means that when the fitting is as high as it's ever going to go, there's a long length of unused chain dangling from the point where the hook meets the adjustable side of the supporting loop. I usually just leave that hang, but you could make another hook on the free end and use that to bundle it up if you cared.
posted by flabdablet at 10:47 AM on March 10, 2023

clove hitch is sortawrong.

pipe <-- taught line hitch
|
| <-- cord
|
lamp <-- taught line hitch

gives you flex to adjust on both top and bottom. memail me if you like, eagle scout & tock climbing instructor.

cheers!
posted by j_curiouser at 6:00 PM on March 10, 2023

If the taut line hitch and the other sliding knots mentioned above don't work for you, blame the cord. It's probably too stiff. You want something soft and flexible.

There are many options for small, cheap gizmos that might be easier than knots. Search under "line tensioner". It's a little hard to tell what diameter line each different type is designed for, though.
posted by SemiSalt at 5:30 AM on March 11, 2023

Thanks all, I ended up using the taut-line hitch and it worked perfectly.
posted by backseatpilot at 8:24 AM on March 15, 2023