How to decorate porch with plastic pumpkins?

I think this is the one you are looking for!

https://www.hometalk.com/diy/decorate/pumpkins/pumpkin-planters-38909484?

I put rocks i them with white Christmas lites all over you could group them and use one string for 3 pumpkins

Transform them with duck tape- easy, longlasting, and waterproof.

You could put some next to your door on either side. If you have any steps, you could line some up there. You could put some on any furniture you may have on the porch. I have used felt and styrofoam pumpkins under my covered porch and they hold up great!

You can see my porch here and I have used some faux pumpkins: https://www.aratariathome.com/blog/cozy-fall-front-porch-tour

Here's a cute project using a plastic pumpkin as a planter: https://www.hometalk.com/diy/craft/holiday-crafts/copper-pumpkin-planter-20580928

Depending on the size of pumpkins you have, you could put them on a string and hang them on your porch. You could even put solar lights in them. If you have a porch light, you could cover the light with a pumpkin. Also put a few pumpkins down the length of your sidewalk or driveway. Let the trick-or-treaters know they are welcome. Good luck and Happy Halloween.