Indoors is probably not ideal but if you must grow indoors you will have to buy some fluoresent lights. Shop lights and the spiral one will work. You could probably get enough light if you line the sides of whatever you will put the plant in with foil or some other reflective material. The soil will need to be sphagnum peat or long fibered sphagnum. You can find these at most garden centers but you need to be sure that there are no additives. Humidity is not needed for this plant. Unless you live in 0% humidity the plant will adjust to your conditions. Venus flytraps will need to be fairly wet. submerging the pot up to 1/4 its hight is a good amount of water. If you live in an area like New York City or your house has an aftermarket faucet attachment like an RO filter the tap water will be fine. I have been using mine and have had great results. However in many areas the tap water is unsuitable and you will need to get distilled water from the supermarket. Letting the tap water sit overnight will not get rid of the minerals that are the problem. One thing that you will need to consider is dormancy. All venus flytaps need to go dormant each winter, just like the trees in your neighborhood. If they do not get this dormancy they will weaken and eventually die. So it is much easier to grow them outdoors. Do you have a reason for growing them indoors?

These are NOT indoor plants. When the danger of frost is over put it outside in FULL SUN until fall. Once dormancy starts place in a cold, freeze free area until Mid February. Mine spend winter in my fridge.

This is a typical VFT grown indoors.
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They may do fairly well indoors in the short run, but not in the long run. It's a set up for slow death. They are temperate plants and are adapted for all four seasons, including the winter dormancy.

They are also ultra-light lovers and artificial lighting isn't enough. They need direct sunshine.

Although being a classic carnivorous plant, they are not at all good candidates for growing indoors.

You would need pretty strong fluorescent lighting and must keep the plant generally close to the lights. Use reverse-osmosis water, rainwater, distilled, or tap water if it has a ppm of 100 or lower. Many growers grow flytraps in a 1:1 ratio of 1 part peat moss to one part perlite or sand. Don't grow them entirely indoors in an almost completely stable environment or they will die eventually from no dormancy. Once it is late October to early November, accustom the plant to lower light levels and temperatures. Soon after, get them used to the sun and climate outdoors and they will gently drowse themselves to sleep for the upcoming winter. When spring starts you can get the Venus flytrap acclimated to fluorescent lighting again and grow it indoors. In the winter, the plant may look like crap but don't think that it's dead; this is just the flytrap in it's dormancy stage and once spring starts it'll have new greener growth.

Good luck!

If you want to grow it indoors, keep it in a widow where it will get a lot of sun light...
The more sun it gets, the better it will do...
Outdoors really is best for them...
I wouldn't recommend using tap water, but if you do use tap water, flush it about once or twice a month with distilled water & you "should" be fine...

Don't feed it, let it catch its own food / Might be hard indoors though...
If you do have to feed it, make sure you feed it insects that are small & will fit totally inside the trap...
If there is parts of the bugs that stick outside of the traps (i.e. wings, legs etc.) when they decay they will rot the traps...
Traps will/should reopen once they finnish digesting the insect...

A mix of peat & sand is a good mix for VFTs...
Don't use the green decorative moss, get New Zealand Moss if you can...
I like to use a mix of peat, sand & chopped NZ moss for my VFTs...

Good Luck,
E E G

Wow I can't believe I left out the part about dormancy but I think the others covered it well. I put mine outside in September for the ques they need to go dormant and decrease the amount of water. When they look dead, or not very good, I unpot them and lay them on moist sphagnum it a tupperware container and put it in the fridge for 3 months or until I see new growth, spraying if they feel dry or pouring water out if too wet.Check them weekly for moisture and mold.
I do disagree about not feeding it. When it misses it's victim it has wasted energy and the trap will die sooner. When you feed it, it won't miss if done right. Use tweezers and not your fingers and feed it live food. Spring and summer requirements can be met inside. 10-12 hours light for spring and 14-16 hours for summer. A bright window sill is good but I doubt it will get enough direct light there also. You would have to move it from the east to the south and then to the west windows and handling it that much every day is not good. A sun room would be the ultimate place to grow them inside. The best fluorescent lights are 40w T12 5000K. Anything other than 5000K and you get too much red or too much blue spectrum. Look for Sunstick(Lowes) or ott-lite(Home Depot). You can also use 15w T5 lights but they are very expensive compared to the T12s. If you are worried about energy consumption then T5s would be the way to go. There are too many people out there using HPS and MH which burn up hundreds of watts so I think I'm conserving with the 40w I use.

I am suffering from the same VFT woes.
I have been giving my plant tap water only. Can I boil it to make it better? lower its TDS I mean?
I move my plant inside after dark as it can be rather cool outside is that ok? or can/should I leave it outside?
My plant isn't very interested in catching insects. And its traps are small, half a centimeter or so. How can I catch live preys to feed it? I caught some mosquitoes and spiders and they all died:(

Boiling will only concentrate the minerals. There is less water for the minerals. Where do you live, maybe you can use it as it is. Keep it oustide, moving the plant around will not do it any good. Don't bother with feeding it right now, just let it settle in. It will make big traps when it is ready. There should be small bugs living in your media called springtails that will feed your plant.

I live in Berkeley CA. Tap water here is drinkable but I have no idea about TDS.

Boiling water concentrates the minerals. You're probably thinking Chlorine removal, as in fish.

Thank you for all your advice. I'm obviously not a "serious" VFT grower, but my daughter wanted to try one & I thought it might help with the occasional fruit flies (I have a vermicomposting bin in the kitchen & we sometimes get them).

Taz, thank you so much for posting the picture! So, it looks like it's in a regular pot, & not a covered one, as suggested on the "how-to-care-for a VFT" instructions?

I live in Portland, OR so it's not too difficult for me to collect rain water! Getting enough sunlight might be the challenge for me.