How long does it take for corn to grow to full maturity?
Corn maturity varies depending on the variety and weather conditions but most corn is ready to pick between 65 to 85 days from when it is planted. When you buy the seeds, they should have a "time to maturity" number. This is the number of days from seed to harvest that variety of corn should take.
I only have a 4&1/2 foot wide garden so for good pollenation should I plant 2 or 3 rows of sweet corn?
With a garden shaped like that, I would recommend that you take a look at square foot gardening, especially for corn. You plant in squares, instead of rows and it is easier for smaller gardens.This article has more on square foot gardens: https://www.gardeningknowhow.com/garden-how-to/info/plants-per-square-foot.htm
Is there any special thing I need to do if I had sweet corn planted in the same spot as it is going to be this year? Are P&K and nitrogen requirements the same as field corn?
This article will help with growing sweet corn: https://www.gardeningknowhow.com/edible/vegetables/corn/grow-sweet-corn.htm
What is the best way to water sweet corn?
Since corn has shallow roots, it is best to use a soaker hose (or something similar) to allow the water to penetrate the soil rather than runoff, which usually happens with overhead watering. This article should also help: https://www.gardeningknowhow.com/edible/vegetables/corn/grow-sweet-corn.htm
The corn I planted is 2' to 2 1/2' and the main stalk has branches growing off each plant. Are these supposed to be cut off, or are they part of the producing corn plant?
I have a field of Silver Queen sweet corn and some of the young plants are shriveling up and withering away. They have a scummy substance on the leaves. Is there something I can do?
It sounds like your corn has Stewart's wilt. It often leaves slimy patches on the leaves as this is the bacteria that causes the disease. This article will explain more:
I am growing corn in my backyard for the first time. How long does it take for you to harvest your corn? I live in Florida and it's really hot, and the corn has been in the ground for 2 months now. I'm moving in July. Will my corn be ready? The middle part is there and already looks like wheat growing in the middle.
This really depends on the variety of corn you are growing...60-day, 70-day or 90-day corn. However, most types of corn are usually ready to pick about 20 days after you see signs of the first silk growing. In order to pick the corn, just grab the ear, twist and pull in a downward motion and snap it off quickly.