My plants

Valentine pomelo on US897

seed grown Fukushu.

Steve

How are the Bananas? do you still have them?

I do still have a few they are all in pots inside the house. They take up too much room with the leaves to have em outside. The manzano should flower again in 2020.

Everything looks great!

Josh

Sunshine, the red rose is proud land, the yellow is gold medal

Josh, means a lot coming from a west coaster. LOL

Looking very good. Plants do so much better outside if temperature permits. Do you regularly take note of the temperature in your GH? I would be very interested in knowing outside/inside temps say morning and afternoon. If you have some numbers over some days through winter it will be helpful for me. May be others too.

Just in case you are asking me. I have no temperature reading devices. I calculated the BTU heat load for -10F to hold an inside temperature of +20F and apply the electrical heat supply to meet that. I set the time duration to apply the amount of heat as needed for the outside temperature as predicted.

Steve

Steve that is good info too. So how you go about calculating BTU heat load? I am assuming you know the insulation value and surface area of heat loss and use that info. Without a thermostat it is a good trick to achieve quasi equilibrium with minimal resources.

My question was directed at Matt but your input is welcome as well.

A typical low E double glass window offers r-2.5. I have 2 of these with an airspace giving me 2.5+ 1 +2.5 = 6. One BTU = the amount of heat that can pass through 1 square foot surface with an R value of 1 for a temperature differential of 1 degree F. My calculation show I am prepared for a 30F temperature differential.

I am R6 at 30F gives my 5 BTUs per square foot. Surface area time 5 give maximum load and I used enough bulbs to meet that load. I really was pretty sure that you were asking Matt. but in case. I didn't want to ignore any question not knowing for sure.

Steve

Thanks steve. Your input is always interesting and glad that you decided to pipe-in.

Steve, is the R for insulation? I wish I was more knowledgable in that sense. I was told by a California member on another site to insulate the floor. No way I can do that because there are plants in the ground. For some it might be beneficial if everything is potted.

Tropic I used to keep record, in a journal highs and lows inside the GH and out.. I'll use F because a lot of Americans on here lol. I use one 1500 watt heater and a fan. On the odd cold nights in the low teens I'll add another heater set to low.

Most mornings so far outside average is around 28F in the greenhouse 52F

Afternoons - Outside between 30-36F Greenhouse 60-68F Sun makes all the difference.

I have been watching the temps for 3 years now. Nov-Dec temps are in the low 60's. January can get cold upper 50's and then Feb is Spring time. I think it's bumped a zone from 9B to 10A with that second heater. I hope I wasn't jumping all over the place.

Thanks Matt. Did not realize you have a heater (or two) in their too.

R is a measure of insulation effectiveness. It is a measure of how well it resists loss of heat. You can double up your plastic sheet to get much better insulation. You need a air gap between the sheets. So putting one sheet outside the frame and second sheet inside the frame will achieve that. It will cut down the light a bit.

I do not see a point in insulating the floor of a greenhouse. Earth is a good source of heat. To reduce heat loss from the floor a better option will be to insulate the perimeter. Dig out a trench say 2-3 feet just under and outside the frame like a foundation. Insert foam board insulation in that trench and backfill. It will prevent heat loss to outside through the ground. You want your foam boards to be as thick as possible. You can double/triple the boards to achieve that.

R is resistance to movement of heat.

1 BTU pass through a wall with a (R=1) for a temperature differential 1 degree F

BTU's = wall Area X temp differential divided by R

My greenhouse BTU = 63 square feet X (20F-(-10F) X (1/6) = 315 BTU's

1 watt produces 3.41 BTU's.

315 BTU's divided by 3.41 BTUs per watt = my wattage needed = 92 watts

My setup =23 watts 4 bulbs = 92 watts.

I have an R-20 roof insilator that knocks out the heat loss of 9 square feet

54SQFT X 30F X 1/6 = 270 BTU = 79 watts

79 Watts is to 30F = 92 watts is to 35F differential.

I am good to go this winter

Your trees in ground beet in pots any way you slice it. You can always water with 100F water and blow warm air down against the ground.

Steve

YOu guys are just fantastic in your endevours to keep your plants healthy and growing all winter long.

Matt, good work. I love that Rose. Is it fragrant?

Yes Mike, it is quite fragrant from start to finish. I never would have thought roses would be growing in late Nov.

Here is the same rose 4 or 5 days in(Nov 15). I can't remember the zone, but not for 5b.

My favourite is Gold Medal

This one smells sooo good.(Nov 15)
as of today both roses are still holding their petals.

They are beautiful, Matt! I have only one rose (Lady X in a container, not fragrant), which is dormant, sitting in a cooler room. I brought it indoors later than I did my tropical trees. Here are the last flowers from it from weeks ago:

It is my daughter's favorite rose :)