In most cases pets will not eat poisonous plants if you have them around your yard. Even pets, such as rabbits, that normally eat vegetation will eat around plants that are poisonous. You may have noticed this if you have ever gone for a drive in the country and past a field with livestock. Often times you will see a clump of plants growing with everything around them eaten down; this is because the uneaten plants are unpalatable, or poisonous, and the animals know this (for example buttercups).
As such there is no reason to rip out your garden if you already have one established, however you may wish to avoid planting certain plants.
Some common poisonous plants include:
However the biggest concern to pets are onions, garlic, grapes and some lilies.
Onions and garlic are plants our pets might be drawn to eat. Onions and garlic both have been linked to cause anemia in pets, and if they eat to much at one time, these plants can be fatal. It might be best to avoid planting these just to be safe, because pets will eat them.
Grapes are also toxic in large amounts to dogs. You should keep our grape vines in such a way that dogs cannot get the grapes.
Lilies are toxic and some lilies have an extra risk to cats. It is not the lily itself but the pollen. A cat who brushes up against a lily, or who rests under it, may get pollen on their fur. The problem occurs when the cat grooms itself and ingests the pollen, which can be quite fatal. The tiger lily and easter lily are most concerning, and since this is a risk your cat cannot knowingly avoid, these lilies should never be kept in yards where cats live, nor should they be brought into homes with pet cats.
Additionally if any plants have been treated with chemicals – either to kill insects, or weeds, the plants could be toxic to our pets.