There's a lot to this deck, and a lot you can change since Sylvans, and in general, Plants can be very modular in how you build them. Since I last made a deck list for them we've gotten Dancepione, which is by far one of the best support cards for Sylvans and a decent support for Plant decks in general.
Without too much, I'll just give a basic rundown on the deck and what it aims to do:
Monsters:
Spore - Spore can be an amazing extender and is one of the more reliable ways to get out Chaos Ruler and get to either Baronne or Chaos Angel, which opens up plays for another Rank-8 and allows for follow-up on following turns should you go first (detach Chaos Ruler > goes into GY and doesn't get banished).
Rose Lover - I left her at 2, she's great for pitching from your hand and extending where you really need to extend, but you don't need her at 3 since she might clog your hand up and doesn't have much use outside of a follow up for your next turn.
Peaskeeper - Peaskeeper is best at 3 I think, you ideally want to be able to summon a few as well as be able to mill it into the GY with a Lonefire already in the GY, which is a target for it.
Cherubsprout - A great card for extending, but doesn't do much unless you can special summon it, I think 2 of it is optimal.
Snapdrassinagon - I added a 2nd copy of it just for more extending, it's great to be able to pitch it and use multiple copies for something like Chaos Ruler, as well for "Lily" Borea since it will pretty much proc for any reason to excavate.
Princessprout - Her at 3 is debatable, you can add in another extender, but 2-3 I would say is probably the sweet spot, she's not a brick or garnet and can get off any plays should you have extenders. Her level modularity also helps the deck into making Synchros and/or Rank-8s.
Rikka Petal - I wouldn't say you need her in the deck honestly (because she locks you into Plants if you search) but she's still good in a pinch, and you have plenty of Plant XYZ to make use of should you get Plant locked.
Lonefire Blossom - Instant 3 of, more chances to put it in the GY from your excavations and it's a fantastic starter.
Peaskeeper - Initially I had it at 3 because he was the only real Normal Summon and has a better chance at hitting than Peaskeeper, but I think 1 is for the best currently, you have plenty of ways to extend and get your plays off, and he doesn't do much if you don't have your Normal Summon aside from be a monster pop at best.
Flowerbot - You can pitch it, get rid of garnets, draw 1, and get a controlled top mill with it, I replaced a copy of Mount Sylvania for it.
Romarin - Aside from Garden Rose Maiden (which I will get to) it's one of your main ways to get Spore and/or Rose Lover into the GY (and if you really need, Lonefire), and it being a Tuner means you can make Synchro plays.
Princess - A great extender + monster negate, helps you get into Dancepione which will be one of your first summons if you can help it. You can make Chaos Ruler with her as well, you just have to summon it by any effect other than her own (Dancepione or Rose Lover).
Sagequoia - I think 3 of him it perfectly fine honestly, though you can run 2 and still be fine, but odds are you want to see at least one of him in your starting hand to extend and maybe even make Chaos Ruler with Spore, which more than likely can get you to any of your level 10 Synchros.
Hermitree - Not completely necessary but does allow you to have a more controlled mill, or lets you know "hey, I probably should shuffle my deck, these are all spells". Going into him off of a Lonefire for Synchro or Rank-8 plays also work, and the extra draw really doesn't hurt.
Snowdrop - Petal and her are the only 2 Plants in the deck that hard lock you into Plants if you use their effects, but most of the time (at least ideally) you'll be something them off of any other effect you can, especially Snowdrop. She makes Synchro and especially Rank-8 plays that much easier, and by extension should you need it, lets you get some extra board space cleared up that way.
"Lily" Borea - A 1-of for her is completely fine, she gets you proc Snap's effect by and can get you started/extend if you really need it.
Mardel - Easily a 1-of, she's a bit of a garnet in your hand and you preferably don't use Rose Lover on her even though she's a search for "Lily" Borea or any other card. Lonefire > Mardel > Search what you need (we'll say Princess) > SS Princess > Dancepione > Continue Combo.
Spells:
Feather Duster - The only real S/T removal this deck has outside of the ED monsters.
Pot of Avarice - I think it's fine as a 1-of, you're able to get to it a decent amount of times off of either Princessprite or Alsei (preferably not Alsei), just good draw power and can help get you back anything you'd want in the deck.
One for One - Easily the best starter in the deck, if you go uninterupted you can usually end on a full board with enough luck.
Sylvan Charity - This is probably going to be Ash'd more than anything else in your deck, so if something is Ash'd, you'd want it to be this. Draw 3 and stack your deck, means getting rid of any garnets like Cherub.
Sylvania - A decent card, but I've opted for 1 copy since we have Flowerbot.
Extra Deck:
Chaos Ruler - Very easy to make and can help you extend quite a lot, on it's own can set up your entire board.
Baronne - You can replace this with Chaos Angel, Dis Pater, or any other Synchro 10 you think will fit, but I've opted for her over Angel just so you can interact more with your opponent.
Princessprite - I'd say 1-2 copies of her is best, you can reset her if you really need and ideally you'll be pushing for game since this deck doens't really have much staying power due to the nature of the deck.
Numeron Dragon - Easy to make with Draglubion and can easily set you up for an OTK, pretty much no matter how strong your opponent's monster is (since you'll have almost no trouble churning out Rank-8s)
Queen Strenna - An easy addition, helps get you to Teardrop just by doing your Jasmine plays, plus lets you add back any Plant from your GY which can help with extending.
Orea - Helps get you a controlled mill and helps you set up plays (you can also use Strenna's effect to get him on the board). It also has a non-targeting bounce of up to 3 cards (yours or your opponents).
Alsei - Instant inclusion, lets you add any card if you really need it and know what you're going to top-deck, and it also lets you bounce an opponent's card for just doing what you were going to do anyways.
Titanic - Another Draglubion target, lets you negate a spell which the deck really struggles with outside of opening the nuts.
Draglubion - Don't ask.
Teardrop - Quick effect tribute an opponent's monster and extremely easy to make, helps with interupting any opponent's plays (and since it sends their monster for cost it won't proc some stuff)
Zeus - For Zeus plays.
Jasmine - Lets you get stuff into the GY and helps you tribute Strenna for a free summon + Rank 5+ XYZ Plant monster, instant inclusion (1 of is fine).
Dancepione - Any 2 Plants makes her and she is bonkers in this deck, getting her off is your main priority since she can get stuff into the GY and special up to 2 bodies.
Apollosa/Underworld Goddess - Apollosa and Goddess are pretty easy to make in this deck and in general are just fine to have, especially if you have free bodies you don't mind giving up.
120
630
360
540
