Destroying Red Heavy Vines is one way to unlock new passages and access to loot and chests with collectibles in God of War Ragnarok. This page describes the vines found in Vanaheim unlocked in the The Reckoning quest - we explain how to blow up red vines and when you can start doing it.
Locations with Red Heavy Vines
You will start encountering red vines in Vanaheim. You visit this world during The Reckoning main quest.
Vines can block access to loot chests (example in the picture) or new passages. Kratos cannot destroy them right away - they are immune to his weapons.
Unlocking and using sigil arrows
You will be able to destroy red vines only after defeating the Nidhogg boss during The Reckoning quest.
Kratos will get a new companion who can do ranged attacks. Make sure that the character has Sigil Arrows set as active - you change arrows by pressing up on the d-pad.
To destroy red vines you have to:
1) Look at vines and order your companion to shoot a sigil arrow. It will stick to them (example in the picture).
2) Use the Blades of Chaos to set fire to the sigil - use a ranged attack (you need to be within the Blades' range). The fire will move to the vines and make them explode, giving you access to a chest, a collectible or a new passage.
Remember that you can return to locations with the red vines you discovered before getting the sigil arrows. You will fortunately visit some of them again on your way back to Freyr's camp.