SPRING IS COMING – TIME TO THINK ABOUT…. light dep.
To depro your greenhouse is quite simple really. To induce flowering, you just need to block out all light for 12 hours, which in most cases, will consist of simply blocking the sun via some sort of heavy tarp or fabric.
We call it a “blackout tarp”, and this is how we make it:
Tools and Materials Needed:
1 roll of greenhouse tape
1 roll of duct tape
1 roll of 10′ x 100′ (black on white visqueen) panda plastic
60 feet of braided nylon rope (.5″)
3 8′ bamboo stakes
24 4″ Spring Clamps
2 ladders (8 ft pref, 6 ft ok)
Step 1 – Prep your material
Cut two 10′ x 20′ pieces and one 4′ x 20′ piece of the panda plastic (black on white visqueen). You are going to assemble these 3 pieces into one large sheet that is 22′ x 20′. Lay out your 10′ pieces parallel to each other, with a 2 foot gap between them. Then lay our 4′ piece centered over the top of this gap, again parallel to but on top of the other two pieces. Then tape the seems all the way down. Flip the entire 22′ x 20′ piece over and tap the remaining seems along their entire length.
Step 2 – Make a stiff edge on one end
Take 3 8′ pieces of bamboo and duct tape them together so they extend to 20′. Try to select thin and evenly tapered pieces of bamboo. On the 22′ end of the plastic, run the bamboo pole along the edge, entered, andthen fold the plastic over the bamboo. Use greenhouse tape or duct tape to fasten the edge, using a few inches of tape every few feet. Then tape the entire seem twice to create a strong hem. Right above the pole, you are going to poke 2 tiny holes, each about 6′ in from the end, so that you can attach ropes later.
Step 3 – Attach ropes
Take 2 30′ pieces of rope and tie them onto the poles using the holes you created in the last step. You now have a large sheet of plastic capable of blocking the entire top, front, and back surface of your greenhouse, which can be easily pulled over the surface of the entire greenhouse, from back to front, using the ropes attached.
Step 4 – Affix your cover to the back of the greenhouse
Take the 22′ side with no pole and attach it to the exterior of the back wall along the top, over lapping the existing back wall by about 18 inches. Using 4 of the 4″ spring clamps attach the cover to the top bar of the back wall of the greenhouse structures, evenly spacing your clamps along the bar. Then use 1 clamp on each side bar to pin down the 18″ of overlap on the sides.
Step 5 – Make the side pieces
Measure the ends of your greenhouse, remembering to add an extra foot to the top and bottom for overlap. You are going to cut two pieces of panda plastic, each 10′ by approx 12′, to cover the ends of your greenhouse. You can cut off the diagonal corners if you want but it is not necessary. After pulling your top cover over, you are going to use 4″ spring clamps to affix the sheets of visqueen to the bars of the greenhouse frame, using approx 10 clamps spaced evenly around the outside.
Step 6 – Cover your greenhouse
Before depro, it is important to remember to have all your oscillating fans on low, your outtake fan turned off, and your dehumidifier(s) on. Then, using your handy ropes, throw them over the top of the green house, and then have a friend help you easily pull your cover over the entire top surface of your greenhouse. Then, as mentioned in the last step, use your remaining spring clamps to affix your end pieces.
Step 7 – Start your flower cycle
12 hours later, remove the end pieces, toss the ropes back over to the other side, and use them to uncover your greenhouse. At this point your flower cycle has begun. For the next 90% of your flowering cycle you are going to cover your greenhouse every night at bedtime (whatever bedtime is, usually before dark) and then uncover it 12 hours later, give or take 30 minutes.