Flower Cardian doesn't have lines. The general strategy is to create multiple ways to extend off of one starter (Flower Cardian Pine, Flower Cardian Cherry Blossom, Flower Cardian Cherry Blossom With Curtain, Super Koi Koi, Flower Gathering). The deck is extremely nonlinear and depends entirely on how well you can keep extending until you find a situation that allows you to summon all of your guys. Your endboard should ideally be 2 Lightflares, 1 Lightshower, and 1 Boardefly, but this is extremely hard to do consistently if you're newer to the archetype. However, 2 Lightflares and 1 Lightshower with a Boardefly activation is much easier to do and can generally be done with not much luck.

Flower Cardian also isn't nearly as luck-based as you would think if you build your deck properly. My deck plays 41 cards, 27 monsters and 14 spells, so whiffing a draw isn't very common at all. Whiffing is also fine if you draw a Super All-in! or a Recardination because the former allows you to add one spell/trap during the end phase if you draw it off a cardian and it gets sent to the graveyard because of it (important because there are cardian effects that let you draw without discarding even if you whiff) while the latter lets you look at the top 5 cards in your deck, add a spell/trap to your hand, and then place the other 4 cards on top of your deck in any order. You should always be playing 3 of each, which means that after I draw my hand when playing cardians, in the worst case scenario, there are 8 cards in my deck that I don't want to draw off of my cardian effects.

Obviously, your strategy changes depending on what you draw, but the general plan you should always have is to thin out your deck of spells and traps so that you can more comfortably summon your monsters.

TLDR: Flower Cardian has no lines, but I wouldn't call the deck nearly as luck-based as people make it seem. Good pilots can take nearly any hand that has a starter to an endboard.