How do you complete columns like you see em?

This can be tricky, because you don't always get the plants you need (sometimes you'll just get an abundance of pots) which can spell your doom.

The plants you get are:

• Pots
• Melon-pults
• Chompers
• Squash
• Potato Mines (only one)
• Jalapenos
• Tallnuts (only one)
• Pumpkin
• Magnet-shroom (only one)
• Coffee Bean (only one)

The Magnet Shroom is your line of defense against the Jack in the Box and Ladder Zombies, but they will get overwhelmed against the tides, especially with the bucket-head zombies and Football Zombies in the mix. The good news is though, that if a Ladder Zombie does place a ladder down, it will prioritize the ladder over anything else.

Additionally, since the Pumpkins are never-ending, I put them on every row (and once you get the Perk that allows you to plant Pumpkin shells over the top of existing ones, you can use that as your primary means of protection against the waves).

The way I plant the rows is:

• 2-3 rows of Melon-pults
• 1-2 rows of Chompers
• A row of Magnet Shrooms
• An empty row of Pots (use this row for your Potato Mines, Jalapenos and Squash)
• A row of Tallnuts

I then cover all rows (starting from the front) with Pumpkins. For the most part, this should take care of most of the zombies, and hopefully bythe time the Gargantuan Zombies arrive, you will have either all rows covered with Pumpkins (to protect against the Imp Zombies that get thrown by the gargantuan Zombies) and a healthy stack of Jalapenos and Squash.

Jalapenos will get rid of ladders; and a hit from any two of Jalpenos and Squash (i.e., 2 Jalapenos, or 2 Squash, or any mix thereof) will kill a Gargantuan Zombie, which you might be able to deal with before they throw the Imp.

All in all, once things take off you will have to be fast in order to protect your Magnet-shrooms primarily, then use Squash and Jalapenos to deal with the rest of the hordes. Additionally, if you get extra pots, just lay them out in front of everything else in order to slow down the rest of the zombies (not by much, but it can help).

The wiki also has additional strats if that method doesn't work for you.