You can perform a massive swarm with this card and 3 "Naturia Hydrangea". First Normal Summon this card while your opponent controls a monster. Activate this card's effect and summon a "Naturia Hydrangea" from your hand. Since you activated "Naturia Pumpkin's" effect this turn, this will allow you to Special Summon 2 more "Naturia Hydrangea" from your hand.
The above combo works even better if you have 3 "Hydrangea" in hand along with another "Naturia" monster as you can Summon the other monster first and then follow up with the 3 "Hydrangea" from your hand.
This card can create a OTK if you have this card, 3 "Naturia Hydrangea", and any "Naturia" monster with 900 or more ATK in hand. First summon this monster while your opponent controls at least 1 monster. Activate its effect and summon the 900 ATK or greater "Naturia" monster from your hand. Special Summon the 3 "Naturia Hydrangea" in Attack Position. Remove your opponent's monster(s) with something like "Smashing Ground" and attack for game.