the pepper wont harm the plants so thats ok. as to wether it will dis-suade the dog I dont know. worth a try.
try shoving twiggy sticks in and around the plants might get pooch to see/feel the point :o)

When making a dog repelent, you boil the chilis in water and add an organic type oil so it sticks to where you spray it. Strain and spray. Chili chunks won't do much. Twigs work better.

he've killed some of the plants in the garden so wht ive done is dug them up and put bark down in tht area as he tends to do his business in the same spot. Hopefully now this will be his pooping spot.....I dont mind avin a bare patch as long as he just goes there.....fingers crossed eh!
If this doesnt work il av a go at the chillis and sticks...thanks