Q. I have a peach tree loaded with peaches about size of walnuts, the branches hanging way down low, they have a red color to them and hard as a rock. What should I do? Is it too early to trim branches? I think cold weather hurt the tree.
A. It is a bit hard to get a handle on the problem without knowing more about which peach tree variety it is and when it normally has its fruit ripen. It is normal for peach fruits to be "hard as rocks" up until a week or so of a normal harvest time.
They may also develop color long before they are ready to harvest. However, judging from the size you mention (walnuts) and color development, it sounds like the fruits were not thinned earlier (removing many small fruits soon after they developed after flowering so that fruit spacing was about 4 inches apart) or the tree was not watered adequately or both.
Not watering with enough water or frequently enough will also result in an open canopy (lots of space between leaves so you can easily see through it) and small fruit.
Unless you are in a very cold climate or you had a very late hard freeze (hard freeze after flowering) I would not guess you had cold damage.