Wow poor boyfriend will need to water these probably morning and afternoon. The containers are -- really -- too small. I would say all of them would be happier in containers at least FOUR TIMES as big.
The pumpkins might be OK now but as soon as they start to vine they will need more. The morning glories and sunflowers already look like the container is way too shallow. Celosia may be able to handle it a bit longer just because they are drought tolerant, but you said you cut them back (So they are actually bigger plants than they look)? They will keep going through the summer with sufficient room to grow.
If they start getting in trouble, one possible solution for him is to fill a larger container with good, moistened potting mix and put the current containers on top without saucer/catch trays so they can root down through the drainage holes into additional soil. The upper containers will need to be supported somehow so they don't topple off due to wind, bumping into, etc. The roots alone won't be enough to secure them in place.
2-3 weeks is a long time to be away during the height of growing season. They are going to be so big by the time you come home.
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