Answer: If you planted your melons and pumpkins in early summer, the vines are healthy, and have had plenty of moisture and nutrients, the problem is probably due to poor pollination. The size of fruit is dependent on how many seeds are in the fruit, which results from pollen reaching ovules in the female flower. Next year, you can encourage bees to visit by planting lots flowers, applying bee-scent (available in garden centers). You can even pollinate the blossoms yourself using a cotton swab or paintbrush to transfer pollen from male blossoms to the female. I'm not sure of the length of your growing season, but I doubt you'll have a successful crop this year.
If you think your soil may be lacking nutrients, have a sample tested. Your county agricultural extension office (ph# 801/451-3402) has soil testing information. "Beef up" the soil with lots of compost, aged manure, etc. to improve the structure, drainage, moisture- and nutrient-holding capacity. Best of luck next time!
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