I can't say enough about the value of ROCKS in a situation like this ...

Now, I'm not saying you should cover your front yard with knee-high boulders, but some people will park even on top of herbaceous perennials. And I'm guessing the road gets plowed every winter so you don't want to do something with woody stems that will be squished by big snowbanks.

I would do rocks at least 1' tall and hopefully 2' wide. Space them about 10' apart - too close for someone to park in between them. Then fill in the space between the rocks with perennials that die back in the winter and are salt tolerant. I'm not sure about the zone you are in, but a couple plants that I've had good luck with near road sand & salt are Veronica Peduncularis (little blue flowers in the spring, good to zone 4) and some daylilies.

You can buy Veronica P in many places, I had good luck with the plants I purchased from Classy Groundcovers. They grew in rapidly to cover an area between our stone wall & the road, and they survived many winters of salt & sand. They are still going strong (I drive by that house now and then, we moved). I mention CG b/c it sounds like you have a large area to fill and it can be tough to find 50+ plants in stock at local nurseries.

If you don't want to do rocks but do want to deter parking, consider a very thorny shrub like Rosa Rugosa. They also tolerate sand & salt, but will suffer from having snow plowed into them. You'll likely have to prune out the damage each spring and could wind up with a ragged looking shrub line. However, people who park close to them & open their car door will probably scratch their paint (and at least their shins) so they are a deterrent. I'd really go with the rocks, though. It's the easiest solution and if you landscape around them it can really look nice.

Maiden Gras 10'O.C. is what I'm doing at a condo development. Rocks can equal damage or personal injury, especially if that area is in the road layout rather than your property.

Good point. You might want to check your survey to see if the roadside is really your property. If it is, then a nice, decorative fence placed on your property line would do the trick. If you can't afford to do the whole front, do an interrupted fence where sections of fence are spaced between landscaping.
If the roadside is not yours, then a fence will help you keep from thinking that it IS yours. Not yours=not yours to maintain, either.

How 'bout, they park on the lawn or an expanded driveway of the people whom they are visiting! There is no reason for the OP to feel obligated to provide for others.

I live in a seasonal region and know that this is a big issue. One of the issues is that these houses get rented out to people who don't care about anything except their week long party. You have teenagers fighting over girls on your lawn, empties, puke, and all kinds of other things that go with it.

Yes, but the OP didn't say all that, so I was assuming the best in my fellow humans :-) Sorry, momentary lapse.

The picture from the seasonal communities I know (and I know some very well) is that many people wouldn't be able to live in them year-round if it weren't for the contribution of and needs of the seasonal (and weekend) population. To keep that population mannerly is one thing, to try to either shut them out or chase them away is maybe self-defeating, as well as futile.

KarinL

I agree a sign should be the first thing you plant. "No Trespassing" and "Private Property". Then plant your boulders.

This is for your protection. If anyone is hurt on your property you are responsible. They can end up owning your front lawn and your house.

Friend has nice place on river where you can get on boat & go over to gambling casinos. People were parking all over her nicely landscaped area outside her fence. Police wouldn't do a thing. I suggested rocks & some good sized ones were placed among the plants & shrubs. End of problem. They now park in their own yard & make bare spots there,

Plants alone will not do it - they will drive over the plants. A nice grouping of 400-800 lb granite boulders placed amongst the flowers should work.

I had a problem with a small strip between alley and driveway - one guy down the street cut corners and drove across it. Three large boulders later, the problem ended.

And he had a very large gouge in the door of his prized pickup, right at the height of the boulder on the end. :)

Park on the actual roadway and become a traffic hazard, leading to sundry accidents, possibly the death of small children? Park on the neighbours' property, thus spreading the problem? Walk up the road in the dark and become fatalities themselves?

That takes the cake!

Lazygardens - that reminds me of the time a Corvette was being driven by an idiot who hit our mailbox. Our mailbox was held in the ground with one of those 4' long metal spike-things because the ground was so rocky we couldn't dig a good sized hole to bury the 4" post easily, so we drive the metal fence-post holder in the ground & set the mailbox post in that.

Anyways, DH heard someone having a hard time with their car but sort of ignored it. After about 10 min he looked outside, saw the Corvette, and just as he was about to go help the guy the car took off. That's when DH noticed the "car in trouble" was parked where our mailbox used to be. Grrrr.

However, we found some lovely chunks of body panels that had gotten caught on that metal post-holder thing (which was half-pulled out of the ground and bent at a 90 degree angle). I laughed - sure, our mailbox replacement was going to cost us $50 and a couple hours ... but the damage to that guy's car was probably in the $1000 range. The "car in trouble" sounds we heard were that guy trying to get his car disconnected from the mailbox post, he was backing up and charging forward in an attempt to break free.

I still smile when I think about that. I bet you smile when you think about the truck vs. boulder incident :)

It would be nice to protect the cedar hedge so a line of sizable boulders (aplenty in that neck of the woods) in front of them would be my suggestion. The rest: give it up to the motor car god.

KarinL : I would love to be a good neighbor and allow parking on my property the only issue I have, the seasonal neighbors that we have all opted NOT to have driveways so instead of having their visitors park on their lawns they advise them to park across the road on ours. So I am not entirely sympathetic to them. If they had an excess of company and not enough room on theirs I would be entirely happy to let them use our driveway since we have plent of room for vehicles if needed. I like the ideas of boulders but here it is pretty wet so I didnt think it would work out, I did entertain the idea of concrete flower pots spaced apart but figured after a year of being in wet soggy ground it may lean and not look so nice after awhile. I live in zone 5? I think.

I doubt the concrete flower pots would provide much deterrence to rude drivers determined to stash their cars on someone else's property. Anyway, you've got 100' to cover: have you priced those things?

If not boulders, consider big chunks of tree trunk. When the thujas grow large enough to fend for themselves, you can chop up the trunks for firewood.

What about the good ole not trespassing signs, or the "trespassers will be shot" every 20' or so, just sayin!

"No Trespassing" LOL, not "Not Trespassing" MORE COFFEE!!!!

Get round-ish rocks. If they lean, so what.