You could set up a rotating water sprinkler on a motion timer. Everytime a cat gets near the motion sensor it will set off the sprinker and the cats will learn there are other more less stressfull places to eat. A motion sensor should be found at your local hardware store and I don't think the cost is much. Use a rotating sprinker cause they make a lot of noise, noise + water = running cat! Now you can plant away, here are some more suggestions of shade plants, Coleus is an annual here but had beautiful foliage colors. Caladiums, also beautiful colored foliage. One of my favorites is Astilbe, I love the ferny foliage and the flower spikes are a bonus, come in reds pinks cream. Heuchera again beautiful foliage, flowers insignificant. Lady's Mantle, the raindrops glisten on the foliage. As you may have noticed I am really into the foliage, if its not gonna flower all summer I need it to be interesting. I hope this helps you out with your "shady cats". Janet

Thanks for the advice about my cats and the suggestions about the plants. The motion sensor is the only thing we havent tried yet.I will trace the local names for the list of your plants.
I was wondering, do you know how much it take for the astilbes and dicentras bulbs or wharever that is to come out from the ground? Its been like 3 weeks since I put them in and I am starting to worry.

Keep cats in doors, if they are yours, or call animal control to trap them.

Cats kill way too many birds and fledglings are especially vunerable. Get rid of the cats!

I forgot to welcome you Andriana, welcome aboard! The Astilbe are later to show, mine are not showing anything yet, and I have quite a few established ones. Where are you? The bleeding heart should be showing signs of life by now. Janet

thanks everyone for the advice. sorry i got lost, Janet, I live in Athens, Greece, but because of the conditions in my yard, ( shade, moist, pretty cool in summer) I thought I should seek for help in this forum. Your list is really helpful, right now I am tracing the local names of your plants. Thanks again!

I sprinkle Pepper and that keeps them away. You may have to reapply after it rains, but after several week the cats don't come back.

Welcome andriana
I'm dealing with some of the same problems you are right now.I was wondering is the shaded area dry? or moist?
Periwinkle as a ground cover has always been one of my favorites.This site might give you some ideas.When you read on you see about the use in shade.
http://www.naturehills.com/new/Review/Groundreviews/ProductName/Periwinkle.html
I also love bog plants too for shade.particularly elephant ears(common name)they multiply well and if you can find some one who has some,there's more than enough for sharing.
Good luck and have fun
Purple

you must have many cats to cause so much damage. maybe you should plant something attractive to the cats-- catnip or wheat grass-- or grow a dog. they usually help take care of cates.
how cold does athens get during the winter-- I was there
during january and it was 30-40 degrees F at night but
50-60 degrees F during the day.
also how hot in the summer?
Do you have shade all year round in you yard or do you have sun during the winter and spring?

I would think that you would have some success with rhodadendrons and azaleas, many of the spring bulbs-- tulips, crocus, lilies, especially the smaller bulbs that come from the eastern mediterranian area. there are also ferns to consider. sweet woodruff (galium) would be a nice groundcover and some of the european gingers. climbing hydrangia would grow for you.columbine, brunneria, coralbells, foamflowers, hostas-- if you like fragrance try hosta plantagenia.
of course the best way to find what would be good for your area is to talk/correspond with other gardeners in your area that have the same situation. when you see a garden that you like that has shade, knock on the door and ask.

since you are getting responses from the usa, you might find it easier if plant suggestions come with their latin names then you could give those names to a knowledgable nursery to find for you. and sorry i didn't give them too you
diggerb