Either one is good. Clay will dry out faster which can be good and bad. Good because you don't want the plant to stay wet too long, bad because you have to make sure it doesn't dry out completely. Plastic has the opposite effect. If it stays wet too long it will lead to rot but you don't have to water as often. A tall plant in a plastic container will be easily knocked over on windy days whereas clay should be okay (not always). Don't overpot your begonia. This can lead to rot because the soil doesn't dry out as fast as it needs to.

Not ideal. Cacti & Succulents cannot stand waterlogged conditions, so their containers usually have holes in the bottom. They also don't like still humid air which is what you will get in a terrarium. I'm not saying it can't be done but I'm guessing you will have a number of dead plants before long. If so, try putting ferns in your aquarium :)

Hi Ana, I saw those kits on Dr. Foster and Smith web site. Yes I do have a lot of questions because I am just learning. In the warmer weather my focus will be more outdoors with gardening, ponds and Koi. I purchased on the internet Irish Moss seeds for ground cover around my waterfall pond area and planter. Can hardly wait for Spring to come. Well I went to blackjungle.com and purchased for my small terrarium, Dwarf mono grass and a Fern - Humata tyermanii "White Rabbits Foot". Later I will ad one more plant such as African Violet. Not a lot of room to plant in and I have to keep only small plants. I also purchsed a clump of Java Moss. I gather the Java Moss is for only aquariums. Well I have a fresh water aquarium that it will do nicely. Also thinking of maybe putting a tiny bit of the java Moss in my large bowl with black pebble rocks that has a water fountain flowing into. I think it would give it a very nice effect. I do wish blackjungle had more small flowering plants beside Orchids. But back to the nursery for that. Thank you, Theresa

I have an old terrarium thats probably about the same size as that. Mine is made of all metal though. I siliconed all the cracks in it and put the dirt and everything else right in it. If you seal the wood and silicone any crevices it should be just fine to put the dirt right in it. The only problem is finding a safe sealent for wood, but since the terrarium is so small I'll assume you won't be putting any animals in it, and as far as I know any sealents wouldn't harm plants (once dry.) I'll post a picture of my little terrarium tomorrow in the gallery, so go look there later if you'd like to see a picture of mine. I have a small bromeliad and palms, though they'll probably all out grow it eventually. I actually threw it together really quick, so I'll most likely end up re-doing sometime. I think for a small terrarium the simplier the better. I've always wanted to try a small bonzai in a tank and just have the substrate covered with moss. Perhaps a piece of drift wood. Have the substrate nicely hilled or something. You know, a zen-like, minimalist approach. Just an idea.