Freezing Asparagus

A few weeks ago I went to the asparagus farm.  Asparagus is in season in Indiana in May and I bought ten pounds of it.  I don't have a pressure canner so it was necessary to freeze it.   Since I do not have a chest freezer my experience with freezing is limited.  In my personal library I have a book called Stocking Up by Carol Hupping.  Mine is the third edition so I think it was published around 1990.  In it is the following page:

I took a chance and put about a half a pound of asparagus in quart bags with two tablespoons of water and microwaved them for three minutes and put them in the freezer.  Since then I have eaten one.  Which I defrosted enough to easily get it out of the bag by moving it from the freezer to the fridge for a day.  After taking it from the zip lock bag, placing it on a plate with some seasoning,  and microwaving it for two minutes I had a wonderful serving of asparagus.

It was all very easy.  My concern is that there is a lot of bad press about microwaving plastics.  In fact I generally avoid plastic and use only glass in my microwave.   But blanching the asparagus in this way was really easy and the results were great. 

Does any one have a thought on whether blanching vegetables in this way before freezing is safe?