Maybe, but then they'll know you have stuff that is suitable for making the lawn "red". They might want to try to take that anyway.
I suspect the SHTF situation would not exist for all that long though, not long enough to do things like going through one or more gardening seasons, etc., so there wouldn't be much time worry about the scenario of gangs going on missions against preppers. If something happened that caused even the gov't to basically disappear, leaving people to their own indefinitely, enemy countries would take advantage of that opportunity. I would expect the enemies to wait a little while for the die off to happen (to reduce how much work they have to do), then they'd start shipping in millions of their own troops and other people to claim the land. Chinese, Mexicans, UN troops, Russians are all possibilities. The troops would kill off anyone who managed to survive the die off. After all, anyone who can survive the apocalypse would probably also be the type that would not appreciate an oppressive new regime taking over. So, the survivors would have a problem even more formidable than mere gangs.
I'm guessing it may be 3 months before the foreign troops start coming in. I could be way off on the timing, but I'm confident it would happen. No way would the enemies pass up the opportunity, just allowing the survivors to merrily farm their lands and rebuild new communities unhindered. If they encountered fierce resistance from the locals in rural areas, they'd probably capture coastal cities first, and steadily work their way outward from there.