Just let your palms grow. Give 'em a check up every now and then and when you see that something is wrong with your windmills you can intervene. When you see something like brown, silver or yellow spots on the leaves, or some white, brown stuff on them take a picture and post it on this forum. We'll try to help.
Using too much chemicals may damage your plants instead of helping them.
Anyroad, giving your plants a fungicide and insecticide/acaricide spray once a month will help to keep your palms healthy.

Thanks for the tip. Do you know if there is one spray that works for this, or do I need a separate fungicide and insecticide spray? My windmills are 5' tall and look fantastic right now, though some of the fronds are a liitle bit wilted. I'm assuming this is normal since they've just been in the ground 5 days and the weather's still in the 40s at night. I hope these temps and occasional rain won't keep them over watered. During the day it's usually 60-70. I though I'd water them twice a week for now, since they are freshly planted. Do you think that's good?
Thanks.

There is no fungicide-cum-insecticide spray. But there are insecticide-cum-acaricide sprays. Unfortunately I cannot give you any names of them cuz I don't live in America.
What's important you should change the sprays you're gonna use cuz fungi and insects get used to them and after a few applications sprays don't work. So go to the shops and ask for 2 or 3 fungicides that are based on 2/3 different active substances. Ditto insecticides. Use them in turns. You ma use of course a copper-based fungicide.
Bet your windmills look awesome. Don't worry about those wilted fronds. It's gonna be alright. When new shoots have appeared water them like once a week. You should not to pamper the roots. They have to search for the water! You may plant French marigolds near your palms so as to keep away any nasty bugs from the roots of your Trachys.
A good way to chase away many pests from plants is to hang a rotten smelly onion on them. I often do it and never see any greenflies or caterpillars on my plants.
As regards that copper fungicide you mentioned in your first post, it is true you should spray your palms with it before the first frost or rather just as you start winterizing palms. It will help to protect your plants from any bacterial/fungal diseases that may appear during the winter, if you make sure the growing point stays dry. But that's another story...
Sorry for my bad English.

Copper based fungicides are good to use before a damaging freeze since it lowers the bacteria population. When plants are damaged by cold, the weakened plant is susceptible to futher damage by the bacteria. Like mentioned above, copper becomes toxic to the plant when its applied too much. There is also no point spraying the leaves as the problem is in the growing point.

I wouldn't use fungicide or insecticide unless you have a problem. I spray with systemic insecticide because the grasshoppers seem to love my Trachycarpus. I may spray with systemic fungicide once or twice a year. The best way to keep the plant from pests is to keep it healthy. Use a complete well balanced fertilizer such as Carl Pool.

I live in a place where summer is very hot and dry and red spider is a common problem, so I gotta spray my plants quite often to prevent any damage on them, rather than fight those mites off when leaves on my plants are 'silver'. Unfortunately every year we have warmer winters and the warmer the winter the more pests and fungi survive.
To fertilize my plants I use pigeon manure. That makes me sure my 'green kids' get everything they need.
Pity the use of antibiotics in horticulture is banned.