How many people have actually used those denim iron-on patches to repair a fly sheet? Most (all?) fly sheets specify on the tag that they should not be ironed but I’ve heard people suggest this. I’m repairing a (nearly brand new!) Canadian Horsewear Orien 3 fly sheet. Will ironing melt or otherwise ruin the sheet?
I actually ironed ON my horse to fix his blanket one cold winter day --I put a towel under the blanket on his butt and ironed the patch on. Stayed on pretty well. Sorry I don’t know about Fly sheets --try a small test area first.
Foxglove
I’ve used them on winter blankets, they didn’t stay stuck so I ended up sewing them on around the edges.
There was a small hole in my girl’s cute pink cooler (mesh overlay on fleece) and I ironed on a cute martini patch. It looks swell. So far holding up fine. I just noticed another little hole on her kool sheet (I think that’s what it’s called). I’ll see if I can find a cute patch for that one too.
In my experience the iron-on patches don’t stay stuck on. As was mentioned, you can stitch around the edges. You might also want to go to an outdoor store and check out the patching material people use to fix tents. Sticks very well, and is very durable. To be sure, I stitch around patching I do with that stuff also.
Mine have usually melted the fabric!!! I would hand or machine sew a square of nylon netting material over the tear.
Duct tape is your friend. 
