What are some thorny plants that will thrive in zone 6 but also have shallow roots? The reason I ask is my neighbors, despite everything else I've tried, wont keep their dogs out of my yard. I can't plant anything large close to the road, and anything with deep roots would risk my sewer and gas lines. Alternately, is there any plant that will simply repel dogs by scent?

The area is full sun, the soil is clay but sits on a slight incline so it drains fairly well.

EDIT: Thinking about it, I suppose it need not be thorny if it grows thick enough as to be impenetrable. Whatever a dog wouldn't like to walk through and squat on.

  • 1
    A common method to deter dogs would be a fence... (Sorry, but deliberately planting something thorny that would hurt them kind of raises my hackles.)
    – Stephie
    Commented Aug 14, 2017 at 20:08
  • What is the soil like where you want to plant this barrier? How much sun does the area get? And how much wet is the soil? A picture might help.
    – CloneZero
    Commented Aug 14, 2017 at 20:13
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    @Stephie First, I shouldn't have to invest in a fence in the front of my property for dog owners too lazy to carry a plastic bag. Even if I wanted to, I can't put one that close to the road. Second, my assumption is any dog would be smart enough to avoid it. It's not like I'm throwing poisoned meat outside...
    – Patrick
    Commented Aug 14, 2017 at 20:13
  • @CloneZero The soil is clay in full sun, I've updated the question for this.
    – Patrick
    Commented Aug 14, 2017 at 20:18
  • 2
    Just had a very fun thought. Get a motion sensor sprinkler. Fun for people as well. Put up a sign to warn them but this is very inexpensive. Don't worry about roots unless you are planting trees. Even then when plants get enough water on a regular basis they won't need to grow into the water lines. Ace Barberry is my favorite of the barberries and provides great protection to your home against the bad guys. Super foundation plant. Not at all fun to dive into!
    – stormy
    Commented Aug 14, 2017 at 21:01

2 Answers 2


Some examples of Berberis hedges here. As can be seen, they are dense down to ground level, can vary in height and colour and may be clipped closely or left a little wild. They remain looking at least respectable all year round (purpurea when in flower is 'something special'). Planted close together they are impenetrable other than with a bulldozer or similar. Full sun, clay soil and good drainage suits them. Zone 6 conditions are suitable.

  • I don't know how deep my gas lines are either, are these likely safe to plant above them? Or if I were to unearth the pipe to check the depth, what depth is safe?
    – Patrick
    Commented Aug 15, 2017 at 20:59

Cactus is generally a shallow rooted plant. They can be grown in clay soil with a little help (see attached). Growing cacti in clay soil

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