Size of Covering for Mel's Protective Dome Supports?

rachel597(5A ME)November 3, 2009

If I use 10 foot PVC pipe as a protective dome support for a 4x4 SFG like Mel describes on page 71 of his ALL NEW SQUARE FOOT GARDENING, what size in feet should the covering be?

Rachel

GrafixMuse's Garden Spot

Here is a link that might be useful: All New Square Foot Gardening: Grow More in Less Space! By Mel Bartholomew

Thank you for reporting this comment. Undo
eaglesgarden(6b - se PA)

A 10 foot diagonal (the length of the PVC) would mean that the sides should be just a little more than 7 feet long on the edges. If you go with a 8 foot square you should have no trouble! See below for the math!!!

***Warning MATH****

If the diagonal is 10 feet across for a square, it forms a right triangle (45-45-90 degree angles). The legs of the triangle can be found using the sine relationship: sin (45) = leg length/ 10 feet. That becomes: 10 feet*sin(45) = 7.07 feet! If you go with an 8 foot square, you should have about 9 inches or so extra to pin down with bricks, etc.

November 3, 2009 at 12:51PM
Thank you for reporting this comment. Undo
Dan Staley

IMO that particular picture is an inferior design and you want the design with the two pipes that are secured across the 4' span ("covered wagon"), then attach a purlin at the top (per page 76 in the given link).

Then what you have are essentially hoops, easily calculated.

o For hoop fabric I use height x 1.57 then add 18" to make it easy to anchor at the sides.

o So presuming that's a 4' height at center in the book:

1. 4 x 1.57 (+ 18") = (6' 3" + 18") = 7' 9".

Most row covers come in 6 or 7' widths so this means you want less than 4' height for a 7' row cover, and 3.5' height will get you there:

1. 3.5 x 1.57 (+ 18") = (5' 6" + 18") = 7' 0".

Which is a ton of height - my regular hoops are ~ 2' at center. I'd use SCH40 only for this application and a zip tie to secure the tops of the 2 hoops to the purlin.

HTH.

Dan

November 3, 2009 at 3:20PM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

Inferior, huh? What about this one, Dan? Ha!

EG (The crazy inventor)

November 3, 2009 at 10:13PM
Thank you for reporting this comment. Undo
rachel597(5A ME)

Thanks eaglesgarden and dan_staley! I just KNEW someone could help me with the math. Now I will have something to think about over the winter as I plan my garden for next year.

My goal was to have a structure in place so I can quickly cover the garden in the spring in case of frost. I thought MelÂs Dome would be the easiest. However, when I tried to price out the row covers, I worried that the smaller ones may not fit the height of the dome. The modified covered wagon does seem to a better setup for this application.

I was looking for something simple, but I am also watching EGÂs (engineeredgardenÂs) mini greenhouse very carefully. He has more details on his blog: Our Engineered Garden.

Thanks again for your help!
Rachel
GrafixMuse's Garden Spot

November 4, 2009 at 8:38AM
Thank you for reporting this comment. Undo
Dan Staley

Huh. My clever reply has disappeared and I forgot what I wrote - surely something to give the crazy injuneer a hard time. I'll try to take some pix of my overengineered coldframe soon & we can compare crazy projects.

Rachel, I was in HD yesterday and 1/2 in conduit was 1.65 for a 10' piece. Two of those are about the same price as PVC and will last much longer. I'll pick up a few lengths my next trip.

Dan

November 4, 2009 at 9:47AM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

Dan - likely so, I enjoy receiving a good heckling from time to time. Mine is far from finished - as I may install a programmable logic controller on it, with a 4 channel type J thermocouple input module.

Rachel - Thanks for following my creative little greenhouse construction. It's gonna be pretty sweet when finished.

EG

November 4, 2009 at 12:44PM
Thank you for reporting this comment. Undo
Dan Staley

My coldframe design and the heater for it, EG, is being developed for ease of homeowner use and low price point (likely grants will defray costs to homeowners), so I'm injuneering/testing for simplicity, the exact opposite. So that will take some cerebral contortioning on both our parts...

Rachel, in your zone you can still go to HD, get two lths. of conduit, assemble and sow for cool seasons for~ \$10.00 - perhaps even incl. row cover (not incl rebar for anchoring). . I'm in Denver area and my greens are going well (albeit they may get overheated today and tomorrow as we get highs in mid-70Âºs).

Dan

November 5, 2009 at 10:09AM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

Dan - without a doubt, the simple/cheap solution is ideal for the average homeowner. I just want to use my technical knowledge to enhance my greenhouse experience. Since heirloom tomato seedlings will be sold to the public next year, it really needs to be self-sufficient.

EG

November 5, 2009 at 1:18PM
Thank you for reporting this comment. Undo
keski(6)

I found the dome type easy to work with. For a 4' x'4' I just got a 25' length of clear plastic about 4-6ml thick. It is 10' wide and it works just fine with the bricks. I just stuck the half-inch (10')pvc into the corners and secured the cross with cable ties. It held up during a late wet snow we had in April. I can only get hubby to do a couple garden chores a year so I made do with the easy dome.
Keski

November 5, 2009 at 1:22PM
Sign Up to comment
More Discussions
staining wood for raised beds.
I'm wanting to build a raised bed and first went out...
johnmcd348
Watery soil under raised bed
Hey all, I am new to raised beds, just started construction...
jazz1234
What to put in the bottom of 12" high boxes??
Hello all, I am doing my first SFG this year. I live...
Deck Pros
New to gardening and already disappointed in myself :(
I decided to make a raised bed garden and start growing...
cammie895
Corn in sfg-how deep do roots need to grow?
My sfg is only 4x4. I plan this season, only using...
growingup
Sponsored Products
Dura-Trel Camelot 5-ft. Vinyl Wall Trellis - Mocha - 11140M
\$73.99 | Hayneedle
Lucy Accent Chair - LT.BLUE/OFF WHITE
\$1,899.00 | Horchow
Utopia 3-ft Narrow Wraparound, 4 x 25W T8, Single Ballast, 120/277V
LBC Lighting
Americh Vivo 7240 Tub (72" x 40" x 22")
Modern Bathroom
Marina 3 Piece Outdoor Patio Teak Sofa Set in Natural White
\$1,073.00 | LexMod
Indulgence Memory Foam Bath Rug
\$34.50 | FRONTGATE
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™