I thought this year that I would put in a pumpkin patch for my kids and let them have a pumpkin picking party on halloween. I planted a few seeds for giant pumpkins, 2 rows of jack-o-lanterns and a row of mini pumpkins. All of the plants came up and have flowered, but they are not vining or producing pumpkins. They are in very sandy soil, but I read that they like soil well-drained, so I don't think that would be a problem. Not sure why they are not vining - I figured they'de be running all over the place by now. Any ideas?

Pumpkins can grow in rather bad soil and still do okay. Give them time. They do need to be fertilized, and the sandy soil may let nutrients leach away, unless you are using slow release fertilizers such as blood/bone/feathers/manure type items. In my experience, they take the first 6 weeks to just sprout, send down roots and make a few larger leaves. Around 8 weeks they start to send out vines. It takes a good 4 or 5 months for them to develop mature fruit. Once fruit start setting, you want to keep only a couple, further along a vine to give them room to grow. It takes at least 2 months for a pumpkin fruit to mature once it begins to grow. Being so far north, you may need to start them indoors in gallon sized pots to give them enough time to grow, then transplant big plants outside in May so they have enough time to spread out before frost comes.