Considering a small 6x8 greenhouse. Couple questions...

[F. Bennett]

I've been going back and forth with the decision to get a 6x8 greenhouse to extend my season a little. I'm looking at Harbor Freight's model for $150 w/coupon. I understand it will need some improvements to make it worth the purchase. Luckily there are lots of videos with owners providing tips to make it last for years.
I've never owned a GH and I'm wondering if the cost to keep it warn during the colder nights of spring/fall are worth it. If I simply use a space heater, how much higher is your electric bill each month? How early in the year are zone 7 folks using greenhouses w/heaters? Thanks

[fruitnut]

It won't cost much to just ward off freeze damage for 4-6 weeks spring and fall. It's Dec-Febr that get expensive.

You only need to keep it just above freezing. Going for 50-60F gets expensive again.

[F. Bennett]

Thanks for your response. I should add that I do have an attached garage I use to overwinter the trees at optimal dormancy temps. I am simply looking to extend the growing season for some late ripening figs, then put them to sleep.

[DBJohnson]

Check out your local Tractor Supply. I picked up a 6x10 portable greenhouse on clearance for $50.

[F. Bennett]

Thanks Bryant. I will check it out.

[fitzski]

I have an unheated greenhouse that I was able to jumpstart the season with this year and I now have some figs in their that haven't ripened yet.

The nighttime temps usually stay 10-20 degrees higher than outside temps. This morning it was 55 outside and 65 in the greenhouse.

This past spring my figs started leafing out in late March/early April while my in-ground figs didn't leaf out until mid-May.

So for me the unheated greenhouse has worked out well.

[F. Bennett]

Great to hear, Kevin. Thanks for sharing your experience.

[fitzski]

Good Luck with your endeavors. If you have a greenhouse supply company near you, it may be easier to just buy the panels your self and then build a frame which I've heard you have to do with the harbor freight greenhouses.

My greenhouse came from here.

http://www.essexgreenhouse.com/Lincoln.html

A little more expensive than the Harbor Frieght but it survived the boatload of snow we got last winter in New England.

[F. Bennett]

Thanks Kevin!

[Rafaelissimmo]

Frank

My advice is contact Nick Allers, he retrofitted a Harbor Freight GH in Pennsylvania and he did a great job. As for heat, I use a oil burner based digital heater and it is way too expensive. About $100 extra a month. My advice is run a gas line into the gh if you can or otherwise use a cheap oscillating electric heater like I bought at BJs, bill costs probably less than $10 a month. Also, clear pool covers inside the greenhouse is a great way to maximize solar heat during the day.

[F. Bennett]

Thanks Rafael. Any idea how many hours you were using that oscillating heater during that time?

[Rafaelissimmo]

http://forums.gardenweb.com/discussions/1631137/solar-pool-covers-work-well

[Harborseal]

You really can't know until you try it. Besides outside temps, the inside temps will be affected by wind, rain, how well you seal it and what you build it out of. It will help a lot if you put the long side up against your house and the door is sheltered from the wind. If you want to extend your season you'll need daytime temps of 80-85 and night time temps of at least 65-70. You may need to hook up a thermostat or buy a heater with one built in. Oil filled heaters are safer than resistive wire heaters. Quartz heaters are useless. Consider then how many plants you'll fit in and still be able to get to them and how much fruit you'll get from them in 8 weeks or so. Good luck either way. My recommendation? Get 3 60x90 greenhouses

[F. Bennett]

Thanks Bob! Great info. My next house will have space for a larger greenhouse(s).

[Snaglpus]

Frank, I built a small 6x8 around 7 years ago. I got mine from Sam's Club in a kit. Most of these kits are made of aluminum. One of the most expensive cost in building a greenhouse is the floor. My GH cost $499. The floor including the sod cutter, gravel, 4x4, 10mil cover, sand and concrete pavers cost me $500. I know it sounds like a lot but things add up quickly. I keep mine warm using a theromcube and a radiant heater that’s 1500w. You’re gonna have to consider and plan on what lowest temperature you are willing to let your GH reach. My goal was to keep mine around 32. On those days when it reached 5 degrees, my GH was 28 degrees. It would probably have been better if I placed a fan inside but I did not. So far, everything I place inside for winter comes out ahead of everything else by 2 months!

I’m in the process of constructing a new 12x20 GH just behind my 6x8. Those who came to my fig fest noticed that I had taken the top off because I did not plan on a way to keep it cool in June when I started building it! As a tip, that’s also something to think about! Today, I have 2 large fans plus 2 large vents that will open if the GH reaches 70 degrees. I posted step by step building pics on figs4fun a few years back.

Another tips is if you plan on building a GH…..double it! Once built, you will wish you had!


Good luck my friend! I hope my comments helped!

[F. Bennett]

Dennis, thank you for this great info. You are right...needing 'this and that' will add up. It will take some careful planning on my part. Thanks again!

[fitzski]

I agree with Dennis, when planning for the size of the GH, make it larger. Originally, I was thinking of a 6x8 but my wife said "why don't you go for the 6x12". Now I'm glad that I went for the 6x12 as I'm going to need all the space I can get as my fig obsession has grown.

[F. Bennett]

I've looked around my yard, and while I have 1/2 acre of land, anything larger than the 6x8 would not go well in my yard. We will move eventually, which is when I will get very serious about a perfect setup.

[Altadena Mara]

I’m on my second plastic tent greenhouse, since even here in my area of SoCal we used to have weeks of night freezes. I grow an assorted collection of tropical plants that need winter protection. The first 6x8x6 tent (maybe it was 6x10?) worked okay with an electric space heater on a thermostat and greenhouse plastic bubble insulation over the top and sides, even a wool blanket for a few extra cold nights. I didn’t stake it down well one storm and it blew several houses away in a big windstorm. After several years the plastic started tearing, taking it down, putting it up each winter. I bought a new one last year (Grow-It Organic Growers Greenhouse) and it’s much better than the first. The winter was unusually warm so no extra insulation was needed. I’ve left it up and use it for storage. I had a sun lamp on a trolley rail one year, and it added a lot to the heat. However it would burn the leaves if they grew too high. I now use the sun lamp inside in the dining room for sun needy tropicals and keep the greenhouse for dormant tropicals like my plumerias that don’t need light. My electrical bill is twenty or thirty dollars higher for a month or two, but no big deal. It was not much more than when my oldest son lived at home and ran his space heater/TV/PS3/HiFi/ computer all the time.

[F. Bennett]

Mara,
Thanks for the info. I think the extra $20-$30 per month is worth it for me, assuming it's similar cost in VA.

[PA Figs]

Buy the largest greenhouse you can afford and fit! Also, secure secure secure! The wind is more powerful than you can believe. My first greenhouse did $750 of damage to my neighbor's house when it went airborne and it was secured very well, just not well enough. I heat my 10x12 with two electric heaters and enclose the inside with a pool cover. The first heater adds about 15 degrees to outside temps. The seconds adds only an additional 5-10deg.

[F. Bennett]

Thanks for the tip. Great info!

[Snaglpus]

Frank I truly understand what you're going through. Once you build it, you will get a feel what most are saying. Any ideas how you plan on securing it down? I nailed rebar all around the outside of the 4x4 base every 24 inches. Huge wind gust have blown.....I mean completely ripped my pop up window vent off twice. And also blew out one side panel in the middle of a huge rain storm one night. There I was, at 11:30 one hard rainy night trying to get one panel back in. I was drenched from head to toe!

When the window came off, the wind came in from the top and blew out a side panel. I solved that problem by tying the window vent shut with a tight bungee cord and a cinder block placed inside. I also went back and secured each panel with silicone. Today, the wind blows and panels creek a little but they don't pop out any more. Hope this helps.

[WillsC]

Buy the largest greenhouse you can afford and fit!

YUP

[Yeehova]

I made a greenhouse about two years ago about the size you are thinking of. I used 2x4s and 6mil plastic. The greenhouse got pretty hot every day, sometimes over 100° when it was sunny and over 65, even if it had been close to freezing at night. Many of my pants experienced wild temperature swings until I added maybe 6 or 7 five gallon buckets full of water to retain and distribute heat. I supplemented heating with oil lamps only on the coldest days of winter. The next time I build a greenhouse I will probably spend extra for the temperature control.