Gardening in Cold Alberta - Green Peppers & A Micro Greenhouse

Southern Alberta is not really cold in the summer, but the winters can get nasty. Here, we enjoy Chinook winds in the winter months - warm winds that melt the snow and raise the temperature as much as 40 degrees C in 24 hours. In the spring however, the Mother Nature provides us with a variety of conditions. We can have great weather for days, followed by one morning of frost. What to I do in the garden to keep the plants going? Cover them with plastic.
Typically, Southern Alberta will not be guaranteed frost free until June 1st, but most of us who plant gardens here put our plants and seeds in the ground on the Victoria Day long weekend (about the 23nd of May). We usually get a frost the morning following the full moon, and that occurred May 17th so we are probably out of the woods as far as frost goes until the end of September - if we are lucky.
I started my peppers and tomatoes from seed in early March. The plants grew in our kitchen window until about the end of April when I put them out in our most protected greenhouse. The thriving plants are definitely ready to be in the ground and most of our greenhouse dirt is already planted with flowering tomato plants and soon to flower green, red and jalapeño peppers. Outside, Diana and I prepared a special place of protection for additional pepper plants - since we had too many for our two greenhouses.

We selected a plot about 24 inches wide and 11 feet long. Then we dug a trench about 6 inches wide and 4 inches deep, all around the rectangular perimeter of the plot. Next, we planted the pepper plants - 7 of them in the 11 foot row. With each planting, we used liquid fertilizer 15/30/15 to prevent any transplanting shock. (Miracle Grow or RX-15 are two 15/30/15 fertilizer brands I know of.) We added about 4 cups of fertilizer water (1tablespoon per gallon) to each plant. Next, we placed the drip irrigation hose against the stems (we use the kind of drip irrigation hose that weeps from micro pores everywhere along the hose). With the hose in place, we took 2 large plastic garbage bags and cut them down the sides to form long rectangular sheets of plastic. We folded the bags lengthwise, covered half the plot lengthwise and placed big dirt clods in a few strategic places to hold one edge of the plastic. With the fold against the stem of each plant, we cut a + shaped hole for each plant, about 5 inches each way. We then carefully pulled the plants through the holes, overlapping two garbage bags to reach the entire length of the row. We smoothed out the black plastic and I then pushed 6 curved wires through the plastic and into the ground such that the wires entered the ground at the edge of the 24 inch wide plot and along the inside edge of the 6" x 4" trench. Each wire hoop is 88 inches long and about 1/8 diameter and is the kind of wire used for farm fencing (non rusting and fairly bendable). We pushed the wire hoops into the ground about 8 or 10 inches at each end. (Please note: the two end hoops are pushed in at about a 60 degree angle and the bottoms are less than 10 inches away from the first perpendicular hoop. This helps support the end of the clear plastic when it is stretched. Also, the hoops are placed so that none of them pass directly above any plant.) Next, we cut a piece of 2mil clear plastic 6 feet in width and 16 feet in length. (The plastic is not UV stable, but it really only needs to last about 4-6 weeks to accomplish its magic so this isn't a problem. Thin and cheap is the name of the game.) With the clear plastic cut to length, we draped it over the hoops, centered it and piled the dirt from the trench all along its edges. Approximately 4 - 6 inches of plastic was available to sit in the trench, and the piled dirt tightened the plastic nicely.
The result? A perfect micro greenhouse. Now there are a few cautions I need to tell you about before you try this at home...
First, this micro greenhouse is a closed system - meaning that no air is flowing in our out. Inside the tube, humidity levels are high and the plants use and re-use their own oxygen and carbon dioxide. This is OK for a while.

The plastic is nearly all buried. All that remains to be done is to finish covering the closest edge and sweep off the patio blocks. (It the background, you can see two of the drip irrigation hoses.)

Second, if the ambient temperature gets too high, the plants will cook
So... We'll leave our micro climate alone for about a week or so - until the hottest daytime temperatures get up to no more than 78 degrees Fahrenheit. (80 degrees is the maximum upper limit if there is full sun.) When the days are warm enough, we'll stick a knife into the clear plastic and cut 3/4 circles, leaving the top 1/4 of the circles intact so they act like a flap. The circles will be about 4 inches in diameter. We'll cut one circle in each end and two along each side for a total of 6 vents. After about another week or two, the plants will be getting tall. We'll then cut holes directly above each plant so the leaves can get out of the tube. The holes will be about 11 inches across which will mean that there will not be much plastic left on top. At this point, we'll also cut out and enlarge the 3/4 circles along the walls of the tube so there's better ventilation. We'll add a few more holes to the walls too. Eventually, the clear plastic will come off, but it can remain on until harvest - and a nice harvest it will be!!!