Don't those just push into the ground - like obelisks do, they appear like that.

Those bottom spikes look about 12" long and look like the obelisk ones so that's what i'd do, push them in and it'll keep itself upright - again, just like the obelisks.

I wasn't sure as they don't have a sharp point but are just a small thin round. Our ground is sooooo hard and I could only get it about 3 inches in and of course, it leaned very heavily. Thank you.

No, the ends aren't sharp or pointed but they do just push into the ground up to the first level, 12" is a minimum depth for a lot of these types of things.

My ground is stoney and i often have to dig the ground over a couple of weeks before i push the obelisks into the ground or i'd come up against thm stopping me from pushing it deep enough.

There isn't another way of doing this, you can't have those 2 bottom ends ablove the grounds surface or you'll never anchor it and in strond winds it'll shift and that's break any plants you've got growing up it.

I'd suggest doing the same dig over the area before you
push the ends in, stamp it down again, leave it a week or so and then push your arch into the ground.

The metal arch I had came apart half way up and the instructions were -gently tap each upright into the ground with a hammer using a buffer piece of wood (so as the metal is not damaged) and as far as the first rung,taking care not to stand on the lower rung as it may bend and then put on the top section, Although not the same arch as yours it may be the same construction? I remember soaking the ground for ages before I did mine.

Thank you both so much. I'm going to keep a note of your tips and let hubby read this. :-)

My arch didn't come with instructions but do come apart half way as well. We have a rubber mallet and a piece of wood so will use both methods above i.e. digging the ground first, then hammering the lower half in.

Have a great weekend!

Good luck