The Citrus and Banana forums will probably have all of the information you will need.

For citrus, minimum soil temp for growth is 64 degrees and minimum temp for root function (ie, water and nutrient uptake) is 55 degrees. There are all kinds of tricks for keeping the soil warm without heating the whole GH.

For most bananas, minimum for growth is said to be 57-60 degrees.

SB

what are some of the tricks without heating the greenhouse..I have heard of soil bed heaters...

Thanks

Steve

You can put heating cables in the soil in beds...you can put containers on heat mats...the one that intrigues me, and that seems popular, is wrapping each container in a string of Christmas lights...I've wondered whether this messes up the citrus' photoperiodicity though.

sorry about silly questions but are heat mats and soil heat probes safe...I have a heavy gauge external extention cord and my outlet is a grounded box that was built for the pool..which we dont use in the winter...I am a little worried about electricity and the humidity but I think the heavy cord and the pool elect box will be ok

Thanks for all your help

STeve

Hey Steve,

I think that the mats and cables systems are fine with water and humidity by themselves. How you are getting your power to and throughout your GH is another matter. You need GFCI protection either at the breaker or at the outlet. Use the outdoor or waterproof wirenuts for all of your connections. Use "in-use" outlet covers. Watch your amperage; it would take a huge mat to overload a 15amp circuit by itself, but if you had a 1500 watt heater plugged in too, that could do it.

Hope this helps.

Robert

I am going to try to use the minimum amout of heat needed...I have one of those circuits on the pool box....I may only use 3 mats...hopefully I will be able to retain a good amount of heat with bubble wrap...black plastic on north and back walls and lots of soda bottles under plants...I want to use heat as a last resort...I also could bring the plants in house during those cold nights...by the time it gets cold I probally will only have the tropicals in there....

Thanks for your help
Steve

Steven, I have about 8 musa basjoo in my GH right now and am wondering what they will tolerate as well..some of them are dwarf varieities, so i almost think they might die off, altho i hope not...chicago winters are brutal..

We are hoping to use a kerasun heater this winter unless it gets so cold then all of our stuff will have to come indoors..

let me know if you get any special tips..

I can't see heating mats for each individual pot-too much $$

ruth

Typically, if soil is kept warm (65-75) you can get away with somewhat cooler air temperatures. However, from what I hear anything below 55 is bad for bananas. They'll survive, but will appear tattered and stand still.

I was thinking about planting my citrus trees and building a greehouse around them too, but having the greenhouse connected to the house somehow. Perhaps attaching it too the window and leaving that open all the time for heat. Has anyone tried this before? I'm just wondering what the best way to do that would be. Also would the frozen ground outside of the greenhouse creep in or would the warm air inside the greenhouse keep the ground warm too?

If you dig your foundation deep enough, it should stay warm in the greenhouse soil. Or-alternatively you could install hot water pipes or heating cables under the soil to keep it warm and regulate it with a thermostat, keeping it in the 60s at least or nearer to 70 in winter.

I am keeping these in pots.....they are small right now but will continually get bigger pots for them as needed...thanks though

Steve

Depends on the banana variety. Most edible varieties won't tolerate freezing temperatures, but the Musa basjoo that someone mentioned upthread is hardy to zone 6 (and possibly zone 5). I have Musa ornata in my backyard that has survived temperatures below 10 F. It freezes to the ground each Autumn, reappears in Spring, and flowers in August when it is about 6 feet tall.

Bananas aren't happy in cool greenhouses. I kept my greenhouse at 50* nights last winter, and my bananas did terrible. None completely died, but they looked awful and shriveled up, almost dying. The ones I stored dormant in my cellar were MUCH happier. My advice is to keep your greenhouse to a minimum of 60* or store the bananas dormant (in a cool basement, cellar, crawl space of your house). I think they'd be happier living in your house in low light conditions than living in a cold greenhouse. This winter I will store all my bananas dormant rather than keeping them in a cool greenhouse. I wish I could afford to keep the greenhouse warmer, but with propane prices rising weekly, I can't.