Good luck - I think the bag idea works well if you have the area without grass to mow around where the vines will go. Can you train vines for watermelon? I would think the fruit would be too heavy...so let me know if it works - that would be great!
I’m going to use some re-mesh and let the small watermelons grow thru to the top and they will lay on the braced remesh. I have them growing in one of my raised gardens, along the edge, so they will be “suspended” on the remesh. I’m going to do the same thing to the cantaloupe. My summer squashes and cucumbers will be using the remesh but going up. In fact my beans will be growing up on building wire. I’m using rebar for the tomatoes. My tomato growing in a “topsy turvy” died and so did the strawberries. I’m going to try it again, but this time the tomato with basil and lettuce. Only my salads, lettuces, herbs, and bulbs are not going to climb. I’m having a terrible time trying to grow a couple of the heirloom tomatoes. The rest of my seeds seem to be doing ok.
The area with the bags will have pea gravel and no grass, so I think it will work. It’s an area about 16 feet wide, so I’m thinking what can I put in there????? Maybe some yard long beans of each color, climbing nastutiums and I don’t know what else. I cannot find malabar spinach seeds anywhere. Guess, I need to order some, those would be nice with the beans.