My yellow squash flowers start to grow squash, but the squash then starts to rot at the end where flower was.
This is called blossom end rot. This article will help: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
Squash plants look very healthy, but some leaves on plants are turning yellow. Can you tell me why this is happening and what to do about it?
Here is an article that will help: https://www.gardeningknowhow.com/edible/vegetables/squash/why-squash-leaves-turn-yellow.htm
How do squash plants grow?
This article should help with that: https://www.gardeningknowhow.com/edible/vegetables/squash/tips-for-growing-squash.htm
I'm guessing that my yellowing is coming from a lack of iron. I'm probably overwatering a bit. I have heard that I may need some iron, but I don't know anything about that. How much? What kind? Any suggestions would be appreciated.
This article should help: https://www.gardeningknowhow.com/edible/vegetables/squash/why-squash-leaves-turn-yellow.htm
You mention pesticides for taking care of the squash borer, but you don't list any products. I want to use something that is safe to me, my family, and the environment. What do you suggest? Also, what can I do about blossom rot?
Neither organic or non-organic pesticides will work after the plants are infested, as the stem itself keeps the borers from coming in contact with the pesticide. Here are some articles that may help: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-pests-identifying-and-preventing-squash-vine-borer.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
My zucchini and yellow squash was growing well and now all of a sudden the base of the stalks, it is turning a mushy yellow and I can just pull the whole plant off. Is it a bug or fungus? Also, the yellow squash has started turning black and rotting from the bottom up.
It sounds like it has a vine borer. This article will help:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-pests-identifying-and-preventing-squash-vine-borer.htm
What do you do when squash plants are small/short and have blossoms? My plants are quite young, short vined yet have blosoms. Live in northern VT.
You can remove the blossoms to allow the plant to focus on growing larger. It will not hurt the plant and likely they are male blossoms anyway and so will not produce fruit.
On a related note, squash will produce flowers early like this if they are stressed. Lack of water is the most common reason for vegetable plant stress. Try increasing their water a bit.