Question
  I recently ordered a utricularia longifolia from you and it was fine and healthy but now its leaves have this white mold looking stuff on them and some of the leave are turning black. I grow them about 8 inches below 2 40 watt bulbs and the humidity is about 50%. Do you know what could be causing this?
  Also I am interested in building a small greenhouse(approx. 10x15ft.) My house is situates so that our brightest room only gets indirest light the whole day. I have been growing my plants under fluorescent lights but I have heard natural sunlight is by far the best meathod of lighting. I want to grow nepenthes tropical sundews and butterworts in it, and it would get about 4-5 hours of direct sun every day. I live in Memphis TN. Here the summers are in the 90s and some time up to the lower 100s. Hujmidity is rarely below 50%. In winter the temperatures are in the 20s and 30s with occasional snaps down to 15 degrees. How should I heat and cool the greenhouse?(and stil be somewhat low cost) How do you cool and heat your greenhouses?
                             Thanks so much for your help,
                                Dustin


Answer
Hi Dustin,

The white patches are a gray mold that this plant is very prone to.  A Neem spray seems to be the best treatment.  U. longifolia has very waxy leaves, so you may need to put on some gloves and apply the Neem with a cotton ball and actually rub it on the leaves.  Fortunately this fungus seldom kills the plant, it just looks ugly.  It attacks the leaves, but not the roots.

I'll start with cooling in your greenhouse since this is the more difficult affair sometimes.  If you're building it your self, it's well worth the investment to put in a thermostatically controlled vent that has a fan that comes on automatically when the temperature reaches a certain point.  Many nursery supply companies carry these.  Our greenhouse has ends that open completely, so during the summer we just have fans that blow through the whole thing.  However, I wish we had installed thermostatic vents since the spring and fall are a royal pain since it can be hot during the day, and cold at night.  We have to open and close greenhouses manually, and we've had some mishaps because of that.

Heating is simple.  I recommend electric for the basic heating, but have a gas back-up, or go with vented gas heat depending on your natural gas or propane rates and availability.  If you do electric wire your greenhouse for 240 volt in addition to 120.  Your greenhouse is big enough that a typical 1500 watt heater may not be big enough.  Here's an example of the best type of gas heater to use:  http://yaunco.com/featprods/yc_orbiscc3lp.php  You may need to shop around for what works best for you, or the best deal.  I don't recommend un-vented gas heaters.  We damaged some plants a couple years ago using that type of heat.  The reason we use electric as the basic heat is that it is cheaper here in the Northwest.  We have to have propane as a back up for power outages.

Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.cobraplant.com