Expert: Long Island Gardener - 1/31/2007

Question
I have a large fish tank with charcoal, potting soil and gravel on the bottom, and I'm growing some Christmas Cactus in it.  I'd like to remove those plants and put in some bulbs.  My question is, must I change the soil,  then plant new bulbs and will they grow with natural light and artificial light or either/or?

Answer
Succulents such as the disturbingly beautiful Christmas Cactus need an experienced hand to grow successfully in Terrariums.  Most people tend to overwater and overlight their fishbowls and aquariums, leading to an explosion of anaerobic bacteria and blight across the landscape.  In weeks, the experiment is a steamy Black Lagoon.

My guess here is that you have mastered this art form.  There are many bulbous plants that you could grow - I used to prefer Oxalis and Scilla with Selaginella when I had these in college.

If you are covering the tank, natural light runs the risk of overheating - and you don't get a pass for Human Error if someone exposes the glass to direct sun.  In minutes, your Terrarium will be nicely baked and ready for the compost heap.

Certain Light is mandatory if you are going to succeed at blooming anything.  But for plants where only the foliage is enough to make you happy, Fluorescent Lights are fine.  Far Blue Rays is all a green plant needs for Photosynthesis.  To trigger flowering hormones, you need Far Red Rays, and those are almost completely absent in Fluorescent Lamps.  Combining an ordinary Incandescent lightbulb and a Fluorescent Bulb is all you need to get flowers.  Halogen is very bright Incandescent light, but it is a very hot bulb as well and must be kept away from the glass.  You can also combine indirect sunlight for its Far Red ingredient and extend the photoperiod with "full spectrum" Fluorescent Lamps.

You have a lot of choices here.  If you can identify the bulb and your goal(s) I can be clearer and narrow down your options.  RSVP at your leisure and thankyou for writing, Catherine!