I'm thinking of converting my back porch into a sunroom/greenhouse. I could extend the growing season and even use it as a wonderful sitting room. But I'm in zone 6 and it seems like it would be expensive in the winter. Anyone else in colder zones keeping a greenhouse/sunroom? What is your experience? How much does it cost to keep it comfortable in the winter?

You might want to check the posts by "drivewayfarmer"... He did something similar to what you are asking about if memory serves me correctly... he is an excellent resource for both information and quality plants and cuttings and Kerry is Zone 5 in NH....

tsparozi - Thank you so much for the advice I'll check it out!

If your intention is to keep the plants from going dormant, it's my understanding that it's not the best idea as the trees will tend to get leggy and produce fewer fruit. Even the unprotected outdoor figs in warm regions go dormant.

If your intention is to simply extend the season and get more figs to ripen, then it should work quite well. I know several growers who use hoop houses in this manner and it extends the season enough to ripen a lot more fruit. One person suggested that would allow the plants to perform as if in zone 8.

Personally, I'm in zone 6 and I'll be trying some sort of "greenhouse" structure to extend the season for a few in-ground trees next fall....

Just my $0.02

I would if I could.  To optimize the late figs you'd want heat and light.  Some of the best tasting figs are late season and you'd rarely get them to ripen in our zone.

I am hoping to put up a 10x24 hoop house this spring. My plan would be to move my figs(especially the longer season ones) into the hoop house around April 1 and provide heat as needed and then moving them all out mid to late May after last frost. Adding another 5-6 weeks to my season should allow me to grow some more  long season varieties and have all the figs ripen on my early and  mid season varieties. I would put one each of my duplicate early varieties such as RDB in the house and start the other outside to stagger the crop. I wouldn't want to heat it before 4/1.

I have a lot of potted figs over-wintering in the garage. I built some carts so I can start the "fig shuffle" in early April, bringing them in at night as needed. End of season I'll be building some sort of make-shift greenhouse just for the trees that I think will produce well with the addition of a few more weeks. Adding heat may be an option as well....

Further to Chris's comment above, I am also working on putting a STANDALONE Greenhouse / hoophouse. 24x14... The metal for same can be had for about $50 a hoop from a Delaware pipe manufacturer and additional expenses are required for appropriate end wall construction, extra 4x4x8 beams for snow support, doors, vents, poly and so on. Still, I think it can be had for $1000 if you do your own labor....

Piney,
First thing to consider is what side of the house is the porch on? If on the south side and it is clear of shade form trees, then yes, it is very worth it. We had one in z5 and I can't tell how much we enjoyed it. The main thing about figs is you will be able to start them a month or two earlier. I wouldn't concentrate too much on extending them in the fall,  maybe for a month, beyond that most things ripened are pretty meh. It's a really nice way to expand the size of your house in the cooler seasons, spring and fall are the best. A sunny winter day they are great because you can open the door(s) and heat the house. Dog days of summer though, phew..they are like a waste land. Be sure to put roof vents in so the heat can escape out the top, we didn't have that so summer was brutal. Otherwise they are a great place to start veggies and grow figs for part of the year. Also a real nice place for a hot tub, not to mention that a hot tub keeps it a bit warmer on the coldest nights. You can also put poles up to suspend shade cloth above the sun room for the summer which would greatly help with the heat, that was also not an option for our old house.

There's a lot of good advice above.  I think there are three issues:

1.  Is it useful to keep figs warm during winter?  My own opinion is that it isn't, consistent with comments by TorontoJoe.

2.  Is it useful to get figs warm early in the spring?  Here I think the answer is yes, within limits, consistent with the comments from Calvin.  From my own observations of my inground figs, bud break seems to come roughly 7-10 days after a prior 7-10 day period of warm weather.  So if you can move quiescent figs from cold storage into a warm room before it is warm outside, you might get a 2-3 week jump on the season -- without a shuffle.  But without strong sunlight, any foliage is likely to be sensitive and the transition to outdoor conditions might set the figs back somewhat.  So I think you'd want to move the plants outdoors into warmish weather soon after bud break.

3.  Is it useful to keep figs warm in the fall?  Here too I think the answer is yes, within limits.  As Calvin suggests, you might ripen extra figs for a few weeks.  But remember that any figs that will be stored in cold conditions need to acclimate to the cold.  That takes time.  The longer you store the figs in warm conditions, the shorter and tougher the transition to the cold.

FWIW, my wife and I added a sun porch two years ago, and we love it.  It is not heated at all, so we don't use it in the depth of winter.  But sunlight warms the room enough that we can sit "outside" on cool days and evenings in early spring (March - May) and also late fall (October - December).  [My sister slept in the room one night last November.]  And when it's warmer (June - September) we use shades, ventilation and a fan to keep temperatures very comfortable.  Screens keep out the bugs.  

You will love it!!

Think of it as a season extender, either direction, starting cuttings, seedlings, etc or an extension on the end of growing season.  I had fresh tomatoes for dinner today.

On the subject of dormancy-  I have kept fig trees green for three years and have not seen any difference.  The first 2 years I kept some of them in a heated (70f), lit garage (on 24/7 first year and 12on/12off the second year)  I could not tell any difference between the ones kept inside and the ones kept outside.  Now that I have a greenhouse I keep one corner on a light system for my tomatoes, Mexican Guavas, and Tangerines.  The cost for the lighting is negligible and the heat has cost less than $35 so far this year but we have only had 5-6 days of temps less than 32f.  We do not have the winters like you have.

If you do the Sun room right  it will definitely add value to your property, will you recover your costs? who knows, depends on too many variables.

I'm zone 6b, in Boston. 

This is the first year I'm keeping some potted trees in a greenhouse, but I always start my trees very early in March outside there using the same set-up. I don't use any heating -- I simply line the interior of the greenhouse with old five gallon buckets and water jugs. It's nothing fancy, a polycarbonate kit greenhouse with some recycled materials. The water heats up in the buckets and jugs during the day and then radiates the heat back out at night. I put a simple moving quilt over the top of the trees. The daylight warmth is good, but the cold nights keep the tree from waking up. So far everything looks good. Branches are still green at the cambium and none have died. When I start my tomatoes in the spring I have great success -- seeds go in April 1st, they are ready to be planted by mid May. Sometimes it snows outside during those early months, but the plants are fine inside the greenhouse. They grow into very strong plants because they are already used to cool nights and temperature fluctuations, and they transplant very easily. All you have to do is gradually open the windows and doors to get them used to the wind. When I start fig cuttings I just leave them in a pot with moist soil in this same set up, no humidity control or heat. They take a bit longer but almost every one roots and produces strong growth, no leggy shoots. Much better success than trying to grow them inside with heat in my experience. 

Great to read peoples experience and suggestions!
Its unanimous that you will love your greenhouse/sun room!  Best if it faces south but even east or west is nice.  The bigger the better you will be amazed at how many uses you can find. It is nice just to sit inside on a cold sunny winter day.

I have a lien-to 12'x20' so small but excellent for my garden seedlings, plantings, rooted cuttings and some select veggies for both early and late harvests.
Here it is too cold December-March to use it but in April 1st can start using to give early start for some figs and moving some bigger rooted cuttings from inside. 
Use some pails with water to moderate night cold and as needed a heater just to keep it above 7C at night.
I don't use it in summer June-Sep since it is too hot,  Have shading & fan but it still too hot so not worth the effort.
In the fall Oct 1, the reverse put in some small figs to get that little bit extra growth and the odd fig that needs help to ripen.
My kind of investment one you can enjoy.

Thank you for sharing your experiences and setups! It makes me so excited to build something! If you have any pictures I would totally love to see them....

My porch faces west but it still gets a lot of sunlight. It's 11 x 19. The roof slopes from 10 feet to 8 feet. I'll probably use polycarbonate on the roof and glass for the sides. For summer I'll have shading, fans and big windows on the top/sides. For winter there seem to be a few options that could help: insulating the floor and low wall on the sides, putting in thermal mass like water/stones, using a simple solar space heater, and getting triple-pane low e glass for the windows (It seems the low e stuff is controversial).

I'm in Zone 4 in southwest Wisconsin.  I put up a 30x72 greenhouse last year to grow figs in based on 3 years of growing figs in someone else's greenhouse nearby.  In the original experiment I put 8 varieties (Conadria, Hardy Chicago, Green Ischia, Desert King, Brunswick, LSU Gold and 2 other varieties Im not remembering right now) into the ground.  All 8 varieties are still alive after 3 Wisconsin winters and in last year's winter they were not even  mulched or protected. 3 varieties set fruit and Desert King ripened a bit of fruit.  My goal with my new project will be to try to create ways to protect a stump above ground using bales of hay. So far in the greenhouse, which is closed down, the lowest low for air temp has been 11 F which the lowest outside temp has been about -9F.

The best thing about the project is the greenhouse is 100% funded with a grant from NRCS tho I had to come up with the money in advance in order to be reimbursed.  I'll also be putting goji, maypop, pomegranates and a few other experiments in the ground.


 

A 20 degree difference? What is the covering and are you using any heat or thermal mass? Maybe because it's so large the ground is acting as a heat sink.

I was pretty impressed by that in/out temp difference as well....I've never heard of a hoop house providing this much protection. I'm very interested in what you might be doing beyond the poly sheeting? I want to build (something) next fall on a smaller scale and want to get as much bang as I can for my buck

Thanks for posting