You can banish this card from the Graveyard; Special Summon 1 Plant-Type monster from your hand, and if you do, it is unaffected by your opponent's Trap effects this turn. You can only use this effect of "Rose Lover" once per turn.
Sent this Rose Lover to the graveyard where it can use it's effect. Dust Knight sends a EARTH-attribute monster to the graveyard when he is flipped face-up.
Many cards can help you discard monsters to the graveyard, so searching Rose Lover to your hand might be a good idea.
You can use Rose Lover to special summon any Plant-type monster from your hand, so special summon a high leveled one to give you field presence, better if it also has a good effect.