Shopping for a water softener: 1  Salt-based units need to have the salt replenished on a regular basis, usually at a cost of anywhere from $2-$15 a month depending on the cost of the salt ($3-$8 per 40-pound bag) and the amount of salt used by your system.
Milkweed is the common name for perennial, herbaceous plants of genus Asclepias, family Asclepiadaceae (from Greek physician Asclepius). One hundred species occur worldwide; 13 are native to Canada.
1 Hardy Perennials - These milkweed species can survive below freezing temperatures in any zone in the United States. They go dormant in the winter months and return each spring.  Frost Sensitive Perennials - A few milkweeds fall into this category. You can still grow them anywhere in the United States.