I am considering a greenhouse to grow fig trees in-ground primarily to have a variety of figs for eating, sharing with family and friends and selling at local fruit stand.   Hopefully also help reduce the annual work involved in winter protection for Zone 6.

Before I dish out un sacco di soldi (a lot of money) I would love to hear peoples' experience with growing figs in a greenhouse.  Some questions that come to mind;

1. What was the quality of the figs produced compared to those grown in the open?

2. What is the best greenhouse covering (clear or is white better to diffuse some of the sunlight)?

3. What varieties are better suited for greenhouse growing?

4. What training methods work best for in-ground greenhouse growing in a zone 6 climate?   
   

5. Were there difficult issues with diseases or bugs?

6. Suggested temperatures to maintain greenhouse for day and night/summer and winter?
   
   Any other suggestions or issues?

1. Can't produce outdoors. Greenhouse figs can be excellent if not over watered and overly vigorous. Humidity needs to be as low as possible during harvest.

2. I prefer the material that diffuses light, excludes some daytime heat, and holds in a bit of nighttime heat.

3. So far SV, RDB, and St Rita but just getting started on variety selection. The smaller figs that shrivel up have been more to my liking than big watery types like BT and Black Jack.

4. Mine are in pots. The ones I had inground were overly vigorous. Need to adjust water and fertilizer.

5. Prepare for spider mites and scale.

6. Summer shoot for highs 90-100F. Nights are whatever you have outdoors. Heating at night in summer doesn't appeal to me and covering only adds 1-2F. Anytime you close the greenhouse up and start heating humidity becomes an issue.

Winter keep as close to freezing day and night as possible. Can allow warmer by day if you can protect early growth in spring.

If you haven't had a greenhouse before temperature control is the hardest to judge. Look at some real greenhouses in your area and see how they control temp. It takes more cooling on sunny days all yr long than you'd think.

That being said, even with 40 degrees during summer days, and up to 45 I had no problems in a small hoophouse for the last couple years, just have to make sure to water enough.  Nothing ripened in the summer this year so it wasn't an issue, figs in pots with these temperatures needed to be watered twice a day to stop wilting.

Thanks Steve and Chivas for sharing your experience!

Steve,
I am curious you said; "inground were overly vigorous. Need to adjust water and fertilizer". 
If you can manage these by reducing water and fertilizer why did you switch to container growing? 
 

Pino:

I haven't successfully grown them yet planted inground. In 2013 SV inground got totally out of control because the other newly planted trees nearby needed more water than was ideal for figs. That's what happens trying to grow everything side by side. There was fruit but about as much as pots with at least 5 times more foliage. I'm sure it can be done if one has good water control. If your soil has a high water table you might not be able to control growth as you'd like even with no added water.

I'm trying "inground" next yr because I've let the pots root into the ground this fall. Too much watering in pots. My thought is pots rooted into soil would be easy to root prune as needed if vigor is too high. Also other trees are better established now so water can be cut back on everything. My soil has no water table and it doesn't rain much here.

Be aware that even in a greenhouse that sheds rain off your figs, the figs will soon be rooted outside the greenhouse. Then you will lose water control. My citrus are rooted outside and affecting their growth when it does rain. Lots of water off the roof.  Hey, nobody said it would be easy....;-)

Planting in ground, even though this is not in greenhouse, when I plant them in ground outside here, I only water for the first year up to about july or august to get them established.  When the roots are established or a heavy rain comes I back off the water, the following years they get no water what so ever from the hose, only rain.  They still grow quiet vigorously.  For fertilizer I give the first and second year, past that I am just going to get some potassium until I see they need otherwise and some manure top dressed.

Do a search for Greenhouses.  There is a lot of information already here.

Dennis, 
I have been sorting through tons of material on here!
A greenhouse is revealing to have some quite complex aspects.
There are many postings on greenhouse projects and technical issues. 
Would love to hear how these projects worked out how was their experience was it worth it?

Pino:

Buying my greenhouse was the best money I ever spent. Production is many times outdoors on an area basis, and that's an understatment. Quality is the best I've ever had by far across dozens of fruits. Yes there are issues but I've rarely missed a crop on anything. Outside production is so erratic it's hard to form an opinion on what I like. In the greenhouse it's fruit on everything every yr and opinions are easy, learning enhanced. I did build a good greenhouse with excellent controls. Temperature, light, and humidity control are paramount if one wants good results.

I should probably point out that my climate is exceptional for a greenhouse. About 75% sunshine all yr. Mild winters and summers cool and dry enough to maintain optimum greenhouse temps for many fruits.

This is my first year with many figs to speak of in my green house. If the figs do as well as other things I grow it is well worth while. I haven't planted any in ground yet but I do plan to plant a few special ones this year.

Gives me a good head start especially the later variants & protection from potential spring frost/shelter to minimize
abortion due to cold spring night time temperatures. The cons are:

a. Colour of ripe figs not as intense
b. Not as tasty

Given the cons I experienced, I will bring the figs out of green house after mid June. Also, I have roof panels I can
remove. Please note my GH roofing is poly carbonate. I am not sure whether glass green houses outcomes are similar
to poly carbonate ones. I am thinking of adding a small glass green house for special variants like Cdds, I258, Gypsy,
Enrico, Maltese Falcon, Smith etc. 

Glad to hear lots of positives with some cons and challenges of course.
Thanks for your posts!

There was a greenhouse I worked at, there was a tree planted in ground for 30 plus years, under glass, figs got watered all the time for some reason which made them not taste as good, but you could always find some perfectly ripe and they were excellent.  There was some under poly and never got enough light so taste and quality was terrible, they also got tomatoe feed so far from what they needed and ended up with far too much nitrogen.

Thanks for that Chivas! 
It makes sense that glass would allow more light and e closer to the open Sun.  Was the poly you are referring to white or clear?

It was in orange plastic so its very shaded.

Thanks for clarifying Chivas!

For the size greenhouse I am thinking of glass is out of the question.   I am settling for a 20' coldframe  type and
I am trying to decide whether to use clear poly or white poly that blocks some of the light and type of heating.

Several years ago when I got the idea to build a greenhouse I saw an ad in Kijiji for greenhouse glass. They were 16"x16" glass panes from an old tobacco greenhouse. $0.25 each which was practically free. I ended up buying twice the amount I needed for my 10x12 greenhouse. Just an idea if you live near tobacco country. There are a lot of those old greenhouses no longer in use.

Tyler

Hi Tyler
Sounds like you did OK!
I did see a used glass GH  on Kijiji from around London.  It was very large around 40x40 for around $5K.  I couldn't work out the logistics of bringing it here and installing. 

Luckily in my case the farmer had already taken down the old greenhouse and the glass was neatly stacked ready for pickup... but boy was that stuff HEAVY   wow....

Thanks Steve!
It says it has 1.7 R value.  Do you know if you can (or want to) use a double layer?

I don't see where you got 1.7 R value. That seems high for one layer but may be right for two layers inflated.

Two layers inflated has two advantages. A higher R value and reduced wind damage in high wind areas. If you don't get much wind one layer might work. Usually with one layer straps are run over top to hold it down, 2-3 inch wide every 4-6ft.

If two layers one can be clear and one thermal, IR. I think it's clear on the outside. Light transmission of IR is nearly as high as clear. Two layers IR has worked well for me. I end up with 50-60% of outdoors light inside. That's plenty for figs.

Steve, Sooner or later I will understand this a bit better.  Please be patient.  Your experience in this is invaluable

The 1.7R value was in the Q&A of the link you posted.  However reading it again they may be referring to a double layer;

"The R-Value of the Thermal Anti-Condensate Film used in this application would be 1.7." 

Anti condensate does help in commercial greenhouses, but I don't know for smaller ones.  You can buy a spray that adds anti condensate to the plastic but I have heard it's only working so well.  At your peak you can consider putting the top support on top of the hoops and the reason for this is that it stops a good portion of the water that does accumulate to go down the side more than without, many commercial greenhouses here have done this to prevent condensation dripping down onto the crop, it's not 100% but it makes a big difference.  

Pino:

Even with IR double layer inflated or any other greenhouse covering including triple wall polycarbonate, night temperatures will only remain slightly above outside. With heavy overcast as much as 3C higher. But on clear nights under double poly the inside is within a couple degrees of outside by sunset. So it's all night near outside. But the best coverings do reduce heating costs.

If you want inside warmer than outside at night in winter you'll need heat and/or serious insulation, R 10 or 20. That's why I earlier mentioned a highly insulated covering inside the greenhouse. That's what I'd do to over winter figs in your climate.