I've used cut off 2L soda bottle top cloche with and without caps for individual plantings of squash, sunflower, and even corn (bulb planter makes perfectly fitted hole to slide the cloche in.) but had not considered mini single row greenhouses like this. Great idea.

(2L bottles fit perfectly just inside rims of 4"round pots and qt size deli/yogurt containers, BTW)
I notice you are mounding soil alongside to hold them, but high wind situations can still blow them away though. Mine was scattered everywhere after a storm even though they had been fitted in the holes at least 1" deep.
If you are using heat like soldering gun to cut them then you could also make small holes and hold them down with earth staples. I thought about doing that then but I don't like the smell of melting plastic, and it seemed too tedious to punch holes (and they were almost not needed anymore at that point anyway).