A Salted

Being in the nursery business, I get to talk to a lot of people about all kinds of plants and their problems. It can range from, needing something for a shady, wet spot to a hardy plant that can handle extreme temperatures and sun. Deer resistance and a natural fence to block obtrusive neighbors are also on the list. One of the toughest questions to answer is salt tolerance.
As humans, we all know that too much salt is bad for us. High blood pressure being the first thing that comes to mind. Plants can have health issues too, if given or receiving too much salt.
The most commonly used salt, whether found in the closet  or in de-icing during the winter, is sodium chloride. Salt occurs in a variety of forms, including the mineral halite, which is mined and used in rock salt. Sodium chloride is sold in several different particle sizes depending on its intended use. Rock salt is very coarse and consists of crystals that have the consistency of loose gravel. On the opposite end of the scale, common table salt and popcorn salt have very fine granules. In between is kosher salt, which is made up of coarse flakes, and compressed pellets that are used in water softeners.

Most of us think of only these kinds of salt, but salts in irrigation and soil water that we use for our plants are in fact formed from many minerals. These minerals come mostly from the weathering of rocks and soils, dissolved over millions of years. Salts can also come from fertilizers and soil amendments such as gypsum and lime. They can also come from water tables and sea water intrusion. The last two are the problem most people come into contact with when it comes to living on the coast.
Sea water intrusion occurs in coastal freshwater aquifers when the different densities of both the saltwater and freshwater allow the ocean water to intrude into the freshwater aquifer. So you may think that your well water is fine, however, in drought years this difference in densities becomes more lopsided towards the salt water. Too much salt in the soil is a problem for several reasons, including toxicity, inadequate amounts of moisture and oxygen, and a high pH that makes necessary nutrients unavailable to plants. 
Contact your local extension office and get your soil tested if you suspect your soil is too salty.
What kind of symptoms should I look for?
Good Question!

This picture shows a very clear example of what might have happened after a cold, icy, winter, where you threw salt down on your sidewalk to melt ice. Dead, brown plants are an obvious indicator.
What about something a little less obvious?

Leaf tip burn.
Other things to keep an eye out for are:
Noticeable Delay in Spring “budbreak”/flowering
Stunted Foliage and Noticeably Small Buds
Reduced New Shoot Growth
Crown Thinning or Crown Tufting
Premature Fall coloration and defoliation (losing leaves early)

There is a list of plants that can tolerate salty soils (and salt spray if you live on the immediate coast).
Your local extension agent should have a copy for your area. Some of the more common ones, and this is just a small sampling, not all of these will necessarily grow where you live include:

Eastern Red Cedar-Juniperus virginiana
Common persimmon- Diospyros virginiana
Southern magnolia- Magnolia grandiflora
Live oak- Quercus virginiana
Beautyberry- Callicarpa americana
Japanese holly- Ilex crenata
Wax myrtle- Myrica cerifera
Pyracantha- Pyracantha coccinea
Oleander- Nerium oleander

Again, I encourage you to contact your local extension agent, get your soil tested and get a copy of the plants that will grow in your area that are salt tolerant.
As you can imagine, salt in the landscape would be much more difficult to deal with than it would be if you are growing things in containers. It can happen there too!

This is an extreme case.
If you over fertilize your plants, the salts can build up. If the container starts to develop a white crust, or it is seen around the drainage holes, you should look into a possible salt accumulation issue. The nice thing is, you can remedy it rather quickly.
First, stop feeding the plant as often, make sure you are following the manufacturers directions and application rates.
Second, you can try to flush the salts out with plenty of good, clean water. The best thing to do is start over by removing all of the soil and starting with fresh, new soil. In the case above, make sure you scrub the pot, you might even consider soaking the pot in clean water for a few days to try and leach some of the salt out.
As you can see, too much salt is bad for both humans and plants. Hopefully, you won't ever need to worry about this, but if you do, at least you have a little insight as to how to deal with your plants in the case they are ever a salted!!
As always, if you have any questions, comments or concerns about this or any of my other articles, please feel free to contact me at TheCitrusGuy@netzero.com
Happy Growing!
Darren