From what I have read here there are a couple of places where you can get mods that are safe, if that is your worry.
On the garden, you have to water every day or use sprinklers, I don't think the rain works in the aspect of watering the garden like it does in real life.
When I was building my community garden, I was doing so before Aliens and Seasons came out, but this should still work, in one way. I build my garden, planted the plants in rows and fenced it in. Added the sprinklers in where I felt they were best and then took out the gate to keep my sims from playing in the sprinklers. At night I turned on the sprinklers and in the morning I turned them off, replaced the gate and told them to go to work, one was to weed the other was to harvest.
For an inside garden, as someone else stated, you can build one but have to do it with a secton of a wall out for a bit. If you have a maid or butler, you have to make sure that there is no flooring that the water can land on if using sprinklers, they keep mopping it up, which means they are stuck there constantly mopping.
If not watered, the plants will become a brownish color and it will state they are wilting, if from frost where they go dormant, they have the frosted look to them. In Seasons, they will spend most of their time in dormant stages and it will state they can be harvested but due to the frost, they can not be harvested.
To keep zombies out, you will need the fencing around the garden. I don't like to do small gardens at a home, it is too time consuming. So I built a community garden (used buydebug to get all of the plants), saved it and when I start a game I just place it somewhere in town.
hope this is of some help
