Here, your strategy is basically only a slight variation of your daytime tactic, as your main goal will still be to produce as much sunlight as possible. The only difference is that in nighttime levels you cannot rely on random sunlight drops from the sky (it IS dark after all). This makes it all the more important to sow as many sunlight producing plants as possible. It will also make the beginning of Plants vs. Zombies a tad bit more difficult when it is especially crucial to use your rare sunlight as smartly as possible. The good thing about nighttime levels is that you get extra support from fungi which are only active in the dark.
Your first step should be to use your first 50 sunlight to position a Sunflower. Before you are even able to collect your next 25 sunlights, the first zombie is likely to walk onto your yard. This is when you make use of your Puff-shrooms which cost no sunlight at all. These little fighters shoot projectiles with normal damage output at your enemies - only at a short range however.
Position them towards the end of your garden. Don’t worry about losing a few of them along the way, as they recharge quickly and are for free. If there’s a pool, you should do the same thing with Sea-shrooms which also don’t require sunlight.
As soon as you’ve collected some sunlight, you should protect your Puff-shrooms with Wall-nuts which will also buy you some time. We recommend the Scaredy-shrooms as a second fighter to support your Puff-shrooms early in the game, which only cost 25 sunlight and are long-range fighters. It makes most sense to position them as far in the back of your yard as possible as they stop shooting once zombies get too close.
This strategy should guarantee that you make it through all nighttime levels.