I would take the plant out and take care of it outside the terrarium if it needed to be treated for fungus or insects. I don't know of any commercial fertilizer that is not harmful to frogs or geckos but I'm guessing a weak solution of fish emulsion probably would not hurt a frog or gecko. You could also try cactus fertilizer since I have some that says it's very weak in fertilizer. The type of animal depends on the size of the tank. A frog can do good in 10 gallons per frog while a gecko needs at least 20 gallons per gecko. Also, dart frogs like wide tanks while green tree frogs and geckos like taller tanks that are in an upright position. I do have a green tree treefrog in a 10 gallon wide tank but that's only because that was the only tank I had a spare of at the time. Also, I think geckos and other lizards have to have UV lights over their tank.

You will be unable to use fungicides, insecticides, and chemical fertilizers if you have animals in the terrarium. Amphibians have permeable skin and chemicals have no problem entering their systems. You also have to remember that the feeder insects you will be offering your animal can also be a source of contamination if they ingest any of these compounds.

As long as you make sure the plants are free of pests before you introduce them to the terrarium you should be ok. If pests should pop up there is little you can do but remove the plant. Fertilization is usually unnecessary because it will cause the plants to quickly outgrow the terrarium but a weak liquid kelp fertilizer may be something you could try as a foliar feed.

I guess it depends upon what kind of pests. I have a terrarium without animals but had a outbreak of spider mites. I used the old remedy of rubbing down the plants with alcohol and then dishsoap sprays and it seems to have worked. I would think atleast alcohol rub downs which should destroy most eggs, etc. would evaporate quickly without damaging the animals. See what vivarium people say about my idea since I am not experienced with animals.
Good luck
Ivan

If your problem is aphids, before you put in any new pets pop some lady bugs in. These little beauties will eat ALL the aphids in no time. They are a gardeners best friend. :) When their work is done remove them an voila your ready for your pet. It is said that a frog needs to have at least a 10 gallon terrarium and a gecko needs at least a 20 gallon terrarium. Also the gecko will be needing UV lighting, (this helps them process vitamins) and a tight secure lid. They are little houdinis and can escape quite easily.

Hope this Helps,
Rose

i know that blackjungle has some organic fertilizer that they use in their setu ups and suggest for use very sparringly.. check their website..

Thanks for the two new replies. If you notice, this thread is fairly old. I had just gotten frogs at the time. I have learned a lot since then. When I asked the question I knoe at the time that chemicals were not safe, but I think I was asking about some of the organic fertilizers. I have since decided not to risk it. Its not really a good idea to fertilize in a terrarium anyway, even if it is just for plants. With the frogs in there, they are getting enough fertilizer from their waste, and I don't want the plants to outgrow the terrarium. I have seeded with springtails, so that helps keep down mold and rot.

That's okay, even old posts can offer some interesting input. : )

If you did decide to fertilize, I would think that a compost 'tea' might be one of the safer venues -- utilizing homemade compost as opposed to commercial.