First winter with new greenhouse and banana question
 

I built this greenhouse over the summer. I'm keeping palm seedlings, citrus, other tropicals and bananas in it over the winter. In the fall, when I dug up the bananas, I split the large pups off the moms. I stored the moms in the basement dormant like usual and put the pups in the greenhouse to hopefully get a head start for the spring. Now I've split pups in the spring before and they don't seem to miss a beat. However, this fall the pups lost leaves one by one and didn't seem to grow at all. Yesterday I did some investigating and the centers still look good in most. However, two of the basjoo rotted in the center, but sent up new pups themselves. I keep the greenhouse a minimum of 60 at night and it's 75-80 during the day. I heat with a wood stove and supplement with electric heat. I have lights that kick on from 4-8 every night so everything is getting about 13 hours of light a day.

So why aren't these growing? First here are pics of the greenhouse.

Outside looking at it.



Looking in front door.



Basjoo with rotted out center.



Other pups that just won't grow.







Warm 65F in there right now.



Trying to figure this out...any other northern growers with greenhouses?

Re: First winter with new greenhouse and banana question
 

Wow, looks very organized!! Great build.

Re: First winter with new greenhouse and banana question
 

While the bananas may be getting many hours of light, the intensity of light during winter is much lower, so overall your plants may still not be getting enough light energy.

I live in Kansas and grow in a greenhouse. At the winter solstice (when I get the least light during the year), the daily light energy per square foot that I receive is only about 1/4 that which I receive during the summer solstice. Roughly speaking, there are half as many hours of light and the light is only half as intense, which equates to around 1/4 as much light energy.

Last winter I compensated for the lower winter light levels by building large external reflectors on the ground on the south side of my greenhouse that bounced a lot of extra light in (~50% increase in total light hitting the greenhouse). Basically my greenhouse was a combination of a greenhouse and a solar furnace. Under those conditions my bananas grew like crazy at this time of year.

This winter I'm experimenting with not using the reflectors. The results? Almost zero growth, some yellowing leaves, and the rotting of 2 pups that were recently acquired and placed in those conditions. My thinking is that there's an important threshold of minimum average daily light energy for growth and I'm failing to meet it.

Best of luck up there. I'll be rooting for you :)

Re: First winter with new greenhouse and banana question
 

Also, the lights you're using might be too weak or located too far away. I think grow lights are supposed to be mere inches away from the plants, so if your light source is several feet away, the plants won't receive and absorb much energy from it.

Re: First winter with new greenhouse and banana question
 

that looks fantastic, yeah 65 is fine, in the day it will warm up and then when the sun decides to come back out it will get real nice in there.70-80

Re: First winter with new greenhouse and banana question
 

Greenfin,

Wow. All I have to say is thank you. Man, I was figuring since the sun was shining, each hour of "light" was equal. Not the case, I see. Makes sense ... even if it's warm this time of the year, grass and other plants won't grow either. Must be the light levels.

So...now I guess I need to accept that all those pups will be a loss and to NEVER divide in the fall again. I will just dig and store all dormant and divide in March/April when light levels return. I will keep them in the greenhouse and maybe some will resume growth in a few months.

Here's to hoping.

Re: First winter with new greenhouse and banana question
 

Never give up hope :08:

Re: First winter with new greenhouse and banana question
 

Wow, I'm most impressed with your structure and the wood stove is an excellent idea! I think of the heating expense of a greenhouse and shy away from the whole idea but wood stove sparked my interest. We heat a lot with wood in the house but my wife wants a fancy, trendy gas fireplace thing and do away with the old stove and that would be a great use for it. I've scouted firewood for years and haven't been without in 16+. I can still get my firewood fix.

Hang in there with the pups, I think they have a good chance.

Thanks for the photos and inspiration.

:08:

Re: First winter with new greenhouse and banana question
 

Don't get too down, I think you may be able to fix your situation fairly easily if the border outside the south edge of your greenhouse gets hit with a lot of sun. (reflectors won't do you any good if that area is shaded)

You've already built a fine greenhouse, all you need is more light energy hitting the plants. Reflectors are easier to build/buy than you might think. Last year I zip-tied together a bunch of blank white signs that I had leftover from a cancer fundraiser that I organized, so it didn't cost me any extra money, but they can be economically made from many different things even if you have to buy the materials.

One thought would be to get some of those cheap 4' x 8' styrofoam insulation panels (from Home Depot or some such place) that have aluminum foil on one side. If you got 5 of those and laid them side by side on the south side of your greenhouse (suitably held down, perhaps with concrete blocks like I used to hold down my panels), you'd end up with a big reflector that would measure 20' x 8'. That would bounce a ton of extra sunlight into your greenhouse, and would probably give you the light energy you need for strong growth.

4' x 8' panels of plywood (which you could paint bright white and hold down with concrete blocks or some other method) would be more robust, especially if you screw 2' x 4' boards all along the border of the big 20' x 8' reflector created by joining the plywood panels.

If you do something along these lines, burying the edges of the reflector a bit will help prevent wind from getting under it (I buried my edges and used a bunch of concrete blocks). And make sure you have a good pair of sunglasses :)

I bet you could come up with a good solution for a big robust reflector grid for $100 or less. It stinks to have to shell out more money, but on the bright side, a reflector grid will save you some money by lowering your heating costs (thanks to all that extra light energy).

Re: First winter with new greenhouse and banana question
 

Okay, a reflector on the south side ... what angle if any would you shoot for? Or is it on the floor? Just curious.

Re: First winter with new greenhouse and banana question
 

Thanks again! However, unfortunately my greenhouse is 6 inches off the property line to the south, which means the reflectors would be on the neighbors property. That puts me out of luck for using that idea! Ugh!

Re: First winter with new greenhouse and banana question
 

Okay, I understand now. How about the reflectors on the inside north wall of the greenhouse? The horizontal part of the wall. Would that make any difference I wonder?

Re: First winter with new greenhouse and banana question
 

Honestly I don't think light is an issue here. I live far north, and have MUCH less light in the day that anyone else especially with our non-stop cloudy days and excessive rain, and yet, even though my bananas are indoors with a north-facing window and only three dim lights pointed at them, they're doing quite fine. I think there may be something else at play here.

By the way, love the greenhouse, love the wood stove idea. How did you do it? I've always thought about a wood stove, but never thought one could be installed in a greenhouse.

Re: First winter with new greenhouse and banana question
 

Just flat on the ground outside.

Re: First winter with new greenhouse and banana question
 

Yes, reflectors are often put on the inside of the north (vertical) wall in solar greenhouses. I use them there, too. The majority of light that hits the interior of the north wall is heading downward and therefore tends to create a really hot/bright patch where the light is deflected down onto the floor (since that patch gets hit with light from 2 sources--the light that's naturally hitting it + the light that is being bounced off the back wall down onto it).

The bright patch can be a great place to grow things that want a lot of light (fruiting zucchini and tomatoes, for example), but it's possible to overdo it and cook young plants in that zone.

Re: First winter with new greenhouse and banana question
 

but even so..the onlt reason for any type of rotting is either bugs or water..to much of one or to much of the other..no other reason for rot really...we dont grow over winter,only maintain..even here in florida i am only giving the bare minimum minus 10 %..i just want them to carry over until next year..unless you go full spectrum lighting..1000 watts or more,maintain humidity 75%+ plus everything eles..i only grow veg. in winter everything eles is just..i dont water any of my nanners,there down to one new leaf a month..even my Orinocos get nothing until it warms up

Re: First winter with new greenhouse and banana question
 

Dude, can I just say what an awesome greenhouse! Who puts the wood on the stove when you're in bed? Just interested.

Anyway about the pups. You have to remember this is winter, growth will be painfully slow, lights are no good if the pup has no leaves, it will be relying on corm reserves. When you chop a pup it will grow roots first then grow a leaf, the pups that are pupping themselves probably means the pup itself has died for some reason, over watering, fungus, who knows?

Be patient, bottom heat will speed up the root growth, remember roots first, then leaves. Don't worry.

Re: First winter with new greenhouse and banana question
 

I think it's just not warm anuff for your plants to grow, my plants in the winter don't see more than 5-6 hours of light because of the daylight savings thing, and they still only grow about a leaf per week,

Re: First winter with new greenhouse and banana question
 

I'm also wondering if, even though the thermometer says the temps are fine in the middle of the greenhouse, maybe it gets colder around the edges where the plants are. In my greenhouse it can be a lot colder near the plastic than it is a few feet in. You can just feel yourself losing heat when you're in that zone.

Maybe it's a combination of lack of heat, lack of light, and too much water?

Re: First winter with new greenhouse and banana question
 

It might be worthwhile to put a thermometer in the soil of your Basjoo and/or pups to see how cool it gets. If your soil is too cool, that would go a long way toward solving the mystery. I don't know exactly what "too cool" means, but my bananas seem to grow like 5 times faster when the soil is 80F than when it is 55-60F.