Zyra is a lane bully. She excels at long range poke and has excellent lane clear to shove as fast and hard as you choose. With her snares and mid-game slows she has a lot of safety from ganks as well. The confusing strength of Zyra is her bursty ult which is unexpected to lane opponents. Early game park in the middle of the lane to get some seeds going. Use them to hit 2 fast. Take W second if you want poke or E second if you want safety. Ward your sides and keep the lane shoved to cause lost cs from the enemy. Watch for where the enemy jungler might be. You can easily keep the lane under the enemy tower. Don't miss your free seeds, use them every time they pop before the enemy can clear them.

The signature move of Zyra is to run in, root with E and immediately cast Q after which you drop 2 seeds while it is casting. This roots your enemy and gets your long range Q plants shooting at them. However, you can also set up a long range Q plant, then hit the enemy with E after - this still counts as a targeted ability and the Q plant will start shooting at the champ.

Another tip is if you've shoved to the enemy tower, and there are no enemy minions present, you can cast your Q and drop a couple seeds (W) under the tower and you will get 2-3 hits on the enemy while they're trying to kill your minions under the tower.

Mid game your priority is to poke down the enemy laner for a kill or make it so risky that they can't farm effectively. If you get them to back then roam. The obvious choice is a bot lane roam to set the enemy back bot then take dragon.

Note that clearing scuttles is a breeze by dropping seed for E then immediately dropping a seed for Q. This way you get the slow from the E plant while also getting some range with the Q plant as it leaves the slow range.

You should set up pickets for Dragon and Baron. Making the enemy walk through or fight your Q plants to get to your team puts pressure on them.

Once you have Rylai's you can start to snare long range with Q and set up for your assassins.

Zyra has an amazing init for team fights as well. If you can flash in and snare 2-3 enemies with E you can drop seeds for your E to slow them and throw down an Ult then immediately Zhonya. Enemies will NOT fight on your ult. They either scatter or your team will engage. If any get knocked up and your team is on it they're dead. If your team engaged early back up after your Zhonya and follow up with additional Q-W.

The trick to high damage output with Zyra is to make sure you have plants down when you Ult. While the Ult does a healthy amount of burst damage on its own the boosted plants that are in the ring of the Ult will be a significant damage bonus to any team fight.

This is a standard rune setup for an AP mid (though Domination instead of Inspiration). The only rune worth really mentioning is Cheap Shot. In the early game it is a solid choice if you can land your E's. After you get Rylai's it is a big damage boost if you can get your Q plants down before your E plants.