I have three three gallon tanks and a betta in each... no heater but the baseboard heater is right under the stand so I just keep it at a certain temp and it keeps the tanks at the same.... it is important that their water is never below 78... they dont like it less than that.. ideally 80. Anyway.... I use plastic spike like plants... they are just shoots of plastic going straight up... my bettas love to sit in the branches. Your tank is small for a live plant... it will get rot if it comes through to the surface..... and when that gets into the water.... its not good for your betta. I got these plastic plants at walmart for 1.99.... they work.... and they are cheap and wont contaminate your water... I agree with the poster above.. bamboo is dirty... never put anything in your tank that isnt recommended for tank use... people think they can just throw any old rock in a tank... no, you cant.... some rocks have limestone in them which will kill your fish... some have other mineral deposits that are harmful to fish.... best to stick with products made especially for fish tanks.
And dont do full water changes.... half water changes every week..... and use spring water not tap.... bettas are not hard to keep but if you want them to live long you should have a tank that is a little bigger... like my tabletop tanks.... they are small but have aeration, filter, hood, light... rocks and plastic shoot-like plant... they are happy bettas... as soon as they see me in the morning they are all happy swimming back and forth and acting excited... I watch them sometimes and cant believe how in tune they are with their surroundings... how the watch.... move around and watch some more..... then go sit in their plant to contemplate why I didnt feed them ( I only do at night before bed with the odd afternoon bloodworm treat)
And dont do full water changes.... half water changes every week..... and use spring water not tap.... bettas are not hard to keep but if you want them to live long you should have a tank that is a little bigger... like my tabletop tanks.... they are small but have aeration, filter, hood, light... rocks and plastic shoot-like plant... they are happy bettas... as soon as they see me in the morning they are all happy swimming back and forth and acting excited... I watch them sometimes and cant believe how in tune they are with their surroundings... how the watch.... move around and watch some more..... then go sit in their plant to contemplate why I didnt feed them ( I only do at night before bed with the odd afternoon bloodworm treat)