terrarium growing with no fans, can this be done

[craigo12]

hello wanted to grow orchids in a terrarium and want to no if it can be done with no fans.
thanks
craigo12

[Discus]

Can it be done: yes
Is it a good idea: no.

As long as the humidity is low enough and air exchange is high enough, it'll probably work, but if you get problems with fungus and poor growth, likely fans will go a long way to fixing the problem. Pretty much everyone seems to think/find fans are the way forward in enclosed high humidity growing spaces.

[Paul Mc]

While that is true, there are some terrariums that people use which do not have fans. There are the small, table top terrariums that look like bells that you can place over a plant. People use this method for ferns and other low light requirement plants to help increase humidity just a bit around a plant. Personally, I've never done it, but others might have.

When I bought a few mini's two weeks ago, the grower (and a good friend of mine) said they could be grown under those bell shaped terrariums easily.

So, I think it depends upon what type you are wanting to grow and exactly how much humidity there will be.

[jess_hawk]

I had good luck with a terrarium I built without fans. It was fairly small - about an 18 inch cube - and I left a two-inch gap across the front top. Then I put the whole thing in the way of a constant draft.

But of course this wouldn't work so well now that I live in a place where the climate control cycles on and off to keep the proper temperature, instead of just going constantly.

[nenella]

Originally Posted by Discus

Can it be done: yes
Is it a good idea: no.

As long as the humidity is low enough and air exchange is high enough, it'll probably work, but if you get problems with fungus and poor growth, likely fans will go a long way to fixing the problem. Pretty much everyone seems to think/find fans are the way forward in enclosed high humidity growing spaces.

I can only speak about my experience. I have had 2 glass cases with front opening doors; and a wire netting on the top (made for reptiles). I have had these since July 2011. I have filled the bottom with about 4" of terracotta pebbles. Both are in front of a S/SW window respectively. I have a temp & humidity reading meter in each. Up to now, 7 months.... and it works without extra lighting or fans.. But then mine are not 100% enclosed so air gets in and we do open the sliding doors they are in front of depending on the weather (wind/chill factor) - also I have not had any mold or anything forming... I suppose it could happen .. but if I do ever notice anything like that & I do look at my orchids at least once most days... I would remove it & try and sort the problem out. Which brings me to say that I love the OB as this is what this board and it's members are fantastic for..helping each other sort our growing problems!

[Discus]

nenella - what are your humidity readings like? Do you have max/min readings on it, or only ambient (if so, do you remember what the highest and lowest readings have been?).

I assume the terrarium is an exoterra model or something like that?

I bought a small reptile analogue humidity meter and it's utterly hopeless - doesn't even work properly. Perhaps it was part of a bad batch, but the needle hardly moves and the reading is nowhere near the readings on my digital temp/humidity sensor, nor on my humidistat-controlled ultrasonic mist-maker.

[Paul Mc]

I use a terrarium from a company but have the top screen covered with plexiglass. There is a pool of water in the bottom with a pump as well. My humidity averages about 80 percent in there. Without these two items, the humidity ranged around 40 to 50, and sometimes lower depending upon the house. Of course, I needed the high humidity as I was building mine for higher humidity mini's, and there is a fan inside as I blocked the air flow (open screen top).

[Gage]

I have made and kept several non-orchid terrariums with open tops and closed tops, none with fans. So I can't speak for growing orchids in terrariums but I will share some of jar I do know. Some of the terrariums did well, others not as well. To start, sterilizing any substrate and growing media in the oven is very important. This eliminates any mold or other spores that will want to spring up later. As far as closed or open top, some plants like it open some like it closed, but I will say that ferns and moss generally don't need any air circulation to thrive in and of themselves. I have learned a lot of little things doing this but these are the biggest things I've learned.

[nenella]

Originally Posted by Discus

nenella - what are your humidity readings like? Do you have max/min readings on it, or only ambient (if so, do you remember what the highest and lowest readings have been?).

I assume the terrarium is an exoterra model or something like that?

I bought a small reptile analogue humidity meter and it's utterly hopeless - doesn't even work properly. Perhaps it was part of a bad batch, but the needle hardly moves and the reading is nowhere near the readings on my digital temp/humidity sensor, nor on my humidistat-controlled ultrasonic mist-maker.

Hi I know that the highest I get is 99% (just after having watered all mounts as well as poured a couple litres of water to the bottom where the pebbles are)and the lowest I have had is under 50% where I hadn't added water for weeks) Now I add water every 2/3 weeks and I'd say the average humidity I get is about 75%.
I have just looked one case is at 98% the other 77%. The last time I added water was 2 weeks ago.
Temperature wise I've just looked ;today highest has been 20.2°C and lowest 19.8°C. A couple weeks ago when we had the big freeze in Europe I remember temp reading 17°C! - I have digital meters
Oh and yes you are spot on they are both exoterra!

[orchid-eric]

Moving air is very important for all plants. I have 2 tanks, 1 to grow some orchids in my office and 1 to house my sale seedlings. All I did is rip a couple of old computers apart I got out of the trash and took the fans out and found some old phone chargers, spliced the wires and I had air movement. ( FREE )