First Read This Guide Here:
https://steamproxy.com/sharedfiles/filedetails/?id=413942490
Now Do The Following!

After You've Done All That! Next, You Must Kill The Mechanical Boss!

These Three Video's Will Show You How:




Got All That! GREAT! Once You Murder At Least One Of 'em. Solar Eclipses Can Occur. At Least Killing The Enemies During This Event Might Give You The Broken Hero Sword, Which Can Make The Terra Blade, After Combining It With 3 Other Swords:


Next Up:

So If Ya Wanna Beat Plantera: Watch This Video:


If You Win: Plantera Will End Up Dropping A Temple Key Which In That Case You Can Enter The Temple! But If You Fail: Dont Worry: Keep Killing More Mechanical Bosses Until The Plantera Bulb Spawns Again!

So In Order To Go Battle The Golem Follow These Steps:

Step 1:

Kill Lizhards Until One Drops A Lizhard Power Cell!

Step 2:
Find The Golem Spawner!

Step 3:

Watch This Video:


Step 4:

Read Next Guide!

The Final Battle Of 1.2.4 Awaits! Watch This Video To See How It's Done:


Once It Drops The Flairon: Grab It!

Now You Are Prepared For 1.3! See Ya Lata!