The easiest way is to buy a vinyl siding cleaner from L's or HD, they have one that attaches to you garden hose. Be sure to do it first thing in the morning when the siding is cool or on a cloudy day, you don't want the cleaner to dry. We have a 2 story and have done our home several times.
There are some remarkable products on the market which can be used with the standard hose. However, if your home has gone years without being cleaned, you may find it necessary to use a power washer which can be rented or you can hire someone with the equipment to do the work for you. Sorry you are too far away for my son to do the work. Have a nice day!!
http://info.mittenbp.com/blog/bid/202804/Tips-for-Cleaning-and-Caring-for-Your-Home-s-Vinyl-Siding. Great Link for other info on Cleaning Vinyl Siding
Just cover your plants or flowers before spraying as some cleaners will clean the siding beautifully but kill all the plants. Bleach based products work well but will definitely kill plants. good luck
There is a product called 30 Seconds that you can purchase at Ace Hardware that works wonderfully. I use it on my house...You can also use chlorine.