Why didn't my feather plums pampas grass come back? Melville, NY location
Depending on the cultivar that you selected, it may not be fully hardy in your area. This is the lowest climate zone,7, that some varieties can handle, and some will even not perform well here.
If you believe that you have a hardy variety, then the next issue that we need to look at is fertilization. It isn't necessary every year, but doing so every spring will boost your results.
You should also trim this back to 5 or 6 inches from the ground each spring right at the new growth starts to show. This will help the new grass be a little thinner, and help it to flower properly.
This article will help: https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm
It is now middle of May and large pampas grass in Hatteras NC has not been pruned back. Is it too late to do this?
If you have not pruned yet, is the new growth coming in yet?
You have two choices, prune now and risk losing the blooms or wait it out one season.
You can prune out the old plumes to to help the way the plants look.
https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/pruning-pampas-grass.htm
Is pampas grass good for stopping erosion?
Technically, yes Pampas Grass would stop erosion, but it can become invasive and may cause more issues then help.
I've listed some articles with more information.
https://www.gardeningknowhow.com/plant-problems/environmental/plants-for-erosion-control.htm
http://californiacountry.org/features/article.aspx?arID=717
How can I change color of pampas grass
You won't be able to. There are very few shades of pampas grass, and they are colored by genetics. Changing this would require many generations of breeding.
There are many colorful grasses that are often mistaken for pampas grass that may interest you, though. This collection of articles will help: https://www.gardeningknowhow.com/ornamental/foliage/ornamental-grass
Is it possible to change color of pampas grass
You cannot change the color of an existing plant, but you can obtain hybrid plants with pink coloring.
Be sure you know what you are getting into and that pampas grass is appropriate for your geographical area and climate, and for your site. Here's an article that may help:
https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm
I live in North Florida, (Tallahassee), our winters are typically mild, when would you suggest? Thank you
This is as much a matter of convenience and personal preference than what is best for the plant. Some people like the look of the pampas grass even when dried out and tan colored. Other people are "done" with it for the season and ready to cut it down in late fall. Of course, you can enjoy the pampas indoors as a dried flower. Whether fall or spring, the important thing is to cut it down before new growth starts in spring.
How salt tolerant is Pampas Grass? We want to plant it along a sea wall which is subject to salt water flooding.
Yes it is relatively tolerant of ocean side salt spray conditions. Where I come from on the California central coast it grows right up to the waters edge in some locations.
But be sure you know what you are getting into, it can become quite invasive.
Quote from the following article: "Another plus side to growing pampas grass is its tolerance of drought, wind, and salt sprays—which is why you commonly see the plant along coastal regions."
https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm