How to cool a makeshift orchidarium

[RandiRae]

I am currently growing phals, a dendrobium, and random catt/laelio youngings in a covered 75 gallon tank nder lights. I have several issues...answers to any of them would be appreciated!

1. Due to living in an apartment, the temperature is fairly constant. The tank sits around 78 degrees during the day and 74 at night. I don't know how to cool the tank at night. I've tried inserting a computer fan, although it moves the air, the temp doesn't decrease much.

2. I have fluorescent plants lights (the kind purchased at Lowes)..the older ones (t8's?). The lights are about 12-15 ïnches from the phals and about 5-10 inches from the others (some are mounted, others on pots to raise them higher).

3. I've read that the watering should be decreased in the winter...but due to the warmth of my tank, the orchids appear dry. The humidity registers between 45-55 %. Should I mist or water? The bottom of the tank has rocks. I add water but the humidity rarely goes above 60%.

Thanks for reading. I've been attempting to grow orchids for years...never have I had a plant bloom! Many of the phals appear to be healthy (the rest are touch and go). I just feel humiliated for not being about to get a phal to bloom - they're supposed to be the easiest orchids to grow!

[camille1585]

I don't have a tank so can't advise you from personal experience, but I still have a few things to say.

First, What's the wattage of your lights, and how many do you have? How long do you leave them on? Light is one of the main limiting factors when it comes to blooming. You might not have enough light to get blooms.

Another reason you may be having trouble blooming your phals may be because of the constant temperature in your tank. Phals need a 4-6 week cooling down period to induce blooming, and for most people, and for many phals, that means that the natural cooling down at the end of the summer is what will do the trick.

As to decreasing watering in the winter, the only reason to do so is because for most people winter means that the orchids get less light and less heat, so the plants don't need watering as often. In a tank however, the 'rules' might be different since the conditions are better for growing. So unless you have true winter resting orchids, water when they NEED to be watered. If you think that they're dry and need water, go ahead!

Based on the genera you are growing, high humidity is not a huge must have, unless you have mounts and humidity loving plants.

Hope this helps a bit, but I'm not an expert on tank set ups!

[BobInBonita]

Do you have pictures of your plants?

Leaf color can tell a lot about whether a plant is getting enough light. Phals that are dark green need more light, olive green is generally about right. A slight red or purple tint means they are at max (target this for blooms).

How old are your fluroescent tubes? They decrease output with age. T8 is just the size (diameter) not the type of bulb. Different bulbs put out different color temperatures of light. Check the forum for growing under lights (I grow outdoors now, but used to grow under lights and on windowsills in Minnesota years ago).

Is your tank covered? I'd expect higher humidity if it were covered. If it's not covered, then you're going to get only slightly higher humidity than the room humidity. I agree with Camille that you shouldn't need higher humidity for your orchids.

Even in an apartment, you live in WISCONSIN! It's COLD there. You've got PLENTY of cooler air. Can you either move the tank closer to the wall or use your computer fan on a timer with a little plastic dryer duct to move some cooler air towards the plants in the evening? Give them a little day/night temp cycle.

[BananaSlug]

I have a nepnthes tank that I keep cool with a small refridgerator and water pump. I don't know how much you want to spend, or how complex you want to get but it WORKS. I use a Fluval 205 canister filter INSIDE the mini fridge, with the suction and discharge lines running out of the top of thefridge. You have to drill holes in the top of it of course. The discharge line is plumbed into a makeshift radiator made from a coil of copper tubing that is hidden inside the tank and it has a computer fan blowing across it. The suction side of the pump is connected to the other end of the coil, so it just runs in a loop.