Today I gave each of the plants 2 1/2 gallons of compost tea that had Actinovate and azos added to the brew along with a little cane molasses. At the very, very end of the brew I also added a 2 1/2 caps full of liquid fish. You don't want to add the fish to early or the smell can be kind of bad.
I poured the compost tea over the leaves and then poured it at where I would expect the outer bounds of the root system would be and then watered it in.
The compost tea again had alfalfa pellets as part of the brew. The triacontanol hormones in the alfalfa have been shown to help with root growth. In studies, triacontanol was found to increase roots by as much as 26%. These studies weren't done on pumpkin plants, but there is a wealth of study and it seems to work on most garden plants. Many of the same studies show higher yields as well for plants treated with triacontanol (yields = higher pumpkin weights).
What I do is put the alfalfa pellets, compost and other amendments into a paint strainer bag and that all goes into a 5-gallon bucket of non-chlorinated water. I then have a fish tank air pump that runs air through the water to aerate the water. By aerating the water it creates an environment where beneficial bacteria and fungi can thrive and "bad" bacteria and fungi don't do well. The alfalfa soaking in the water helps release the triacontanol into the water creating a super charged liquid ready to grow some giant pumpkins.