Debbie,

No air or filtration needed. Just water, light and warmth.

I don't inject air into or filter any of my aquariums. I have lots of plants and a few fish.

Saw the mention of duckweek and java moss. I bought some java moss from a LSF about 1999 and tossed it into my 15G tank. It did okay but didn't grow all that well. Fast Forward to 2005. I moved into a new house in Dec 2001 and one of the first things i did was set up the aquariums. On one of the rocks was a small, perhaps 2" piece of brown dead-looking java moss. Today the stuff needs to be pared back about every 3 or 4 months. I toss out handfuls.
Duckweed- Some snuck in with a fish purchase. It was nice for a time but did go a bit crazy. I had to get rid of it as it was blocking light to other plants.
Your title say only plnats. That should be VERY EASY. Light and heat as drygulch says. As you will have no fish you can try a bit, 1 tablespoon in a 15 G tank, of household ammonia. Get the stuff with no additives, just plain ammonia. Over the winter only 2 doses should do. The plants love the stuff. The only problem you may have, and this would be a problem with or without the ammonia is algae.

My Java Moss and Fern grom quickly. Light is important. Enough light and you they will do great.

Thank all of you for your advice! I plan on putting some ramhorn snails in this tank also. I thought maybe the snails might help keep the water a little cleaner. And besides I like watching the snails. Would the ammonia bother the snails? So if I understand this correctly all I need is water, light, and warmth. And plants...Thanks again, Debbie

If you add the snails I woud skip the ammonia. To tell you the truth I wouldn't add any ammonia unless you plan on doing a fishless cycle and are going to keep some fish. Careull if you are putting it near a window, dont allow over exposure or algae blooms might occur. Filtration is not necessary but a sponge filter (I use old unused or inexpensive pump/powerheads with a coarse filter sponge over the intake) with minimum surace agitaion and low flow help the Java ferns. Some trace element suppliments would help. Iron supplement and Magnesium (Epsom salts is widely used) help. These are just suggestions, not totally necessary.

I would just add that you only need room temperature heat, as in 74 degrees or so, especially for your pond plants. Too much heat (85 degrees or more) can be worse for plants than too little.

I don't heat my aquariums either. :)

Java fern and mooss and dickeed all have to dreive thier nutrients from the water column. I would suggest to add some macro nutrients suck as potassium nitrate and phospohate as well as as the micro nutrients.

I would counsel against the phosphate, as it's been shown that the presence of this nutrient greatly increases the likelihood of algae problems.

But yes, addition of other nutrients is a good idea.

first of all if you are going to keep the plants growing then plan on getting lights. the lights that come with a fishtank hood are probably 15 to 20 watts....which is useless for growing plants. Secondly those plants are gonna need food...as in CO2, so id recommend getting a small yeast solution CO2 injector (around $15). Also goldfish will DESTROY any plant put in the aquarium so i can almost guarantee if you try to overwinter plants in a tank with goldfish all the plants will be gone in a few weeks. People tend to forget also, that algae will ALWAYS outcompete plants for light and food if the levels of both are low.
Leafy plants (anything not algae) are WAY more complex than algae so they need WAY more nutrients of all types. If those nutrients aren't present in great enough amounts....only one thing will thrive.....algae. If you just want to keep them alive then some low light with no fish and room temp will be fine. They will get algae all over them and most leaves will die but the main body of the plant should be fine till you can replant them in spring. Try to remember also that room temp to us is usually WAY hotter than spring thaw water temps, so taking plants from 70 degree water in your home to put them in 55 degree water outside can be a huge shock to most plants so they will go through some transplant shock.