HE LOVES HYDRANGEAS AND LILLIES !! To gift to his friends, he always tries to abide to colour schemes mainly ! That's more of a me thing but all my ocs are weirdly colour coded so I guess they have those habits. Like forget me not/cornflowers for Kara, peonies/Tulips for Miko, daises/asters for Sona (Sona's colours are black and green so it's more difficult to give him plants) (I feel like he gives Sona's spare flowers that fell off and overtime meaning is incorporated into his gifts and he indulges a little more in flower language when creating arrangements.)

Madoka has gotten every type of flower from him, because every flower meaning applies to her. Madoka isn't big on flowers though but if Itsuki would to stop, she would get upset. It would feel like a weird emptiness in her life. She's probably gotten flowers every month after they've settled down and bought houses/apartments.

She doesn't like bugs so she makes Itsuki double check she won't see any critters hidden in the leaves/flowers too. Those are her own requirements. Oh, and that the flowers not be ugly too.

(Realized I slightly went off the original question my bad. He grows all types of flowers though generally ! His tastes are pretty wide when He's growing them.)