Why do the leaves of my mother's white calla lily plants turn yellow & wither? I can't get them to grow!

I'm in the Los Angeles area; the calla lilies are planted in the garden %26amp; get a lot of sun, but do have some shade. The snails had eaten them right down to the bulbs, so I cleared everything else out of the garden in hopes they would grow. But the stems just get a few inches high and then the leaves turn yellow and eventually wither. Thinking they were getting too much moisture, I stopped watering. Then when I think the soil is dry, I water again, but I don't seem to be having any success getting them to grow. The bulbs are exposed, but they were always exposed even when my mother tended them. Should I put fertilizer on them (they do get Ortho plant food once weekly). There is one plant in a plastic pot that actually produced a few flowers, but now most of the leaves are turning yellow. What am I doing wrong?! they were my mom's favorite flowers, and since she has passed away, I want them to keep growing (they always grew beautifully for her!)-thanks!

Why do the leaves of my mother's white calla lily plants turn yellow %26amp; wither? I can't get them to grow!
there is no such thing as too much water in los angeles, but i should ask if the soil is draining well. as for food you might be giving them too much or too little. right now stop feeding it for about a 3-4 week and just water well. as for the smaller plant isn't getting enough food and might be also water. and feed with an all purpose food fertilizer lightly.
Reply:I have trouble with those too and I have a green thumb. I have found the following problems. Too much water, not enough water, too much fertilizer and some kind of little bug that affects the roots. Mine seem to grow in cycles. Either they are beautiful or so ugly that I hide them. Try not to over fertilize them. Thats just a guess. Check out some of the flowers on my website.