Unexpected Snowstorm Causing Computer Breakdown

The algorithms that govern the computer-controlled environment of our greenhouse were developed under the supervision of Dr. Louis Albright, professor of agricultural and biological engineering at Cornell University in upstate New York.

His brilliant scheme involves running the lights, the Nutrient Pond, the heating, the cooling, the sun shading, the solenoid cells measuring the amount of sunlight—in other words the whole enchilada—off the same master program on our state of the art super-server running Linux as an operating system.

Being a Windows acolyte, while Chuck is of the Mac persuasion, we had to hire a knowledgeable individual to set up our Linux system and to show us how to run it, tweeking it when necessary. We taped his business card to the side of the server, with his cell number highlighted in green.

Green being the color of hope, and also that of lettuce, we figured that we could handle any minor glitches on our own, while for the major ones our Linux genius would be at the other end of a cell phone.

Then came the snowstorm of a few days ago. The computer system managed to survive the invasion of murky water and the subsequent power outage. However, when the unexpected snowstorm dumped an unprecedented two feet of snow onto our Quinset-hut type greenhouse, our Linux system, nicknamed Linus by Chuck, got totally garbled and confused.

Being the practical member of our partnership, I made sure that backup measurements could be taken of the vital signs of our hydroponic lettuce operation. Old fashioned mercury thermometers took the temperature in the greenhouse as well as that of our Nutrient Pond. The digital ones that were hooked up to the computer only showed gobbledygook.

Chuck ran around taking pH readings at different points in the Pond and manually administered a small amount of pH Up in order to correct the acid alkaline balance. I took light readings with a cinematic light meter and adjusted our lighting according to my readings.

Figuring that our lettuce could use an extra boost of immunity, I mixed up a new batch of nutrients, headed by Barricade, a potassium silicate product made by Advanced Nutrients. It strengthens the cell walls of plants and stimulates their immune systems.

I also included Calcium Mg Mix Grow, as well as Mother Earth Super Tea Grow, to fortify our lettuce plants with chelated calcium, magnesium, as well as easily absorbed 100% organic nutrients, that serve the same function as a herbal tea on a cold, winter night.

The Hot Water Boiler had to be run manually, as well, while I put Mr. Linux on speed-dial and bombarded his voice mail with my loud pleas for help.

The polyethylene covering of the greenhouse started to sag under the weight of all that snow. Even though the roof is curved, the snow stuck to it—it was an extra adhesive variety.

Luckily, this type of emergency was anticipated in the design of the structure, so all we had to do was to heat up the forced air in-between the two layers of polyethylene and when it reached the optimum temperature, the snow just slid off the roof and its sides.

The new seedlings had to get an extra treatment with No Shock, and Wilt Stop, since the automatic system failed to deliver their nutrient solution to their holding tanks on time. I also immersed all of them in Scorpion Juice, in order to impart induced systemic resistance, which wards off all sort of pathogens.

After running the greenhouse on manual for the whole afternoon, Mr. Linux was rousted up and spent a couple of hours fixing and recalibrating the automatic system. Afterwards, we presented him with his very own pager, so that when he’s away from his cell phone, he will still be reachable by these intrepid lettuce growers.

Then we had to deal with the delays that the heavy snow caused in our delivery schedules. As the tardy trucks arrived to pick up their daily load of hydroponically-grown Boston lettuce, we slapped chains on their tires so they wouldn’t have any excuses for being late next time.

Polyethylene Covering with Boiler Heating

Some greenhouses are covered in glazed glass. Ours is a more economical model. It is a polyethylene-covered Quonset-type structure, one hundred feet by thirty feet, giving us 3,000 square feet of workspace underneath.

Since a single layer of polyethylene would not protect our hydroponically-grown lettuce from the vagaries of the outside temperature, we’ve used two layers of plastic to cover the structure, then forced air between the two layers to create a four to six inch airspace. This is an excellent insulating barrier; with the onset of winter fast approaching, that is an important consideration.

In the plastic area, several other possible coverings had to be considered. We could have covered our greenhouse with acrylic sheets, polycarbonate plastic, or fibreglass. Polyethylene won out, largely because it is the most cost-effective.

With nighttime temperatures increasingly dropping below freezing, once again we’ve become very aware of how we chose to heat our greenhouse. First, we had to figure out what the anticipated coldest temperature was that we had to deal with, while maintaining an even 68º F (20º C), which is the optimum indoor level for our plants to thrive.

After poring through data going back many years, we found that it rarely dropped below 23º F (-5º C) in our neck of the woods. Most of the time during winter, the thermometer hovered around the freezing point. So we had to purchase a system that could easily deal with such temperature drops, and the occasional dip below the norm.

By a complicated set of calculations involving exchange, conductive, and radiation heat loss, as well as a heat loss coefficient, we arrived at the conclusion that at an outside temperature of 23º F we would need to generate 1,484,861 British Thermal Units per hour (Btu’s) with whatever system we installed.

Of course, our system of 45—600W High Pressure Sodium lights also generates quite a few BTU’s per hour, so that heat had to be factored in.

In addition, we not only had to heat the circulating air around the lettuce, but also the Nutrient Pond, which is their growing medium. Given that many growers urged us to buy a central Boiler and use Hot Water Heating throughout the greenhouse, that’s what we did.

Even though the initial cost outlay was more than using a number of space heaters or forced air ones, the convenience of running hot water pipes underneath the surface of our growing medium, convinced us that this was the way to go.

We chose finned-tube convectors around the walls of the greenhouse, as opposed to straight steel pipes, since they provide four to five times the heat transfer capacity of bare pipe. They’re harder to keep clean, but much more efficient, reducing our heating bill.

In light of the mishap that happened last week, we’re grateful to have a central Boiler system, since in the case of power failure, the water stays hot for a couple of hours, until an alternate source of power can be hooked up.

After the HyOx flush, we administered not only Piranha, Tarantula, and Voodoo Juice, but also SensiZym, Sensi Cal Mg. Mix Grow, and a new batch of our primary nutrients, Micro and Grow.

Our lettuce are well taken care of, and that includes keeping them warm in the winter, and cool in the summer. A number of fans help to circulate the air above our Nutrient Pond, so that no pockets of hot or cold air can damage the sensitive leaves of our lettuce plants.

Howling Winds and Backup Power

Our greenhouse is located near the foothills of a large mountain chain. As a result, it can get windy sometimes. However, we were not prepared for the windstorms of this past week. Up to 62 miles per hour winds howled across this part of the state, accompanied by inches upon inches of deluge type rain.

Roads were blocked by fallen trees and many power line were down. It’s a risk that greenhouse owners have to deal with—our power went out two days ago. A potentially costly disaster, unless one has an alternate plan ready.

As I’ve stated before, Chuck is the visionary. Of the two partners, I’m the practical one. In our initial financial outlay I tried to warn him that something like this might happen. He agreed to spend money on water filtration (see last week’s blog) but when it came to the purchase of an electrical generator, he vetoed the cost.

Everything in our greenhouse runs on electricity. Just to run our 45 – 600W High Pressure Sodium lights for an average of 15 hours a day during winter costs $1,125 per month on our electric bill. And that’s not counting all the other electrical equipment that are necessities in a greenhouse such as ours. Pumps, timers, fans, heaters, etc. all need power.

Please remember that we’ve committed ourselves to producing 400 heads of Boston lettuce a day. Our clients are expecting this output. We can’t just say to them sorry, the lights are out, the pumps aren’t working, our lettuce plants are stagnating, come back next week.

Silvio the practical one jumped into action and grabbed the last available generator at an equipment rental house. I practically had to fight another greenhouse owner for it. We had to hire an electrician to hook everything up to the new power source. We were sweating as hours passed and the greenhouse was still dark.

Since the water in our Nutrient Pond was not flowing for a couple of hours, as soon as the rental generator kicked in, I flushed the system with a weak solution of HyOx once again. The whole area was asked to boil its drinking water, since turbidity in the system was the highest ever recorded. We didn’t want our lettuce plants to soak up potentially harmful bacteria, thus the need for the flush.

I also had to empty our pre-mix and reservoir tanks once again, since the pumps weren’t working and some bad water backed up into them. We had to augment our 180-mesh filter cartridge with a Dacron filter, in order to keep out the newly discharged sediment.

In addition to their regular diet of Micro and Grow, we had to mix in Piranha, Tarantula, and Voodoo Juice, in order to replace the beneficial microbes killed off by the HyOx. I decided to add Barricade powder and agitated the pre-mix like crazy, to make sure it dissolved properly.

Barricade contains potassium silicate, that strengthens the cell walls of our lettuce plants, so they can become resistant to pests and diseases, literally from the inside out.

It was time to give our plants another dose of Sensi Cal Mg Mix Grow, in order to replenish their dwindling supply of calcium. They always perk up after we administer this incredibly nutritious product. In addition to the right types of calcium, it has magnesium, easily absorbed iron, plus essential micronutrients necessary for the enhanced growth of our delicious lettuce.

For the second time in two weeks we all had to work overtime and our shirts were soaked after all systems were humming again. Once the power is restored to the regional grid, we’ll have to have the electrician out again to reconnect our equipment to the main power source.

Then I have to convince Chuck to invest in an alternate system all our own so we won’t have to spend big bucks to rent a generator next time. The system I have in mind includes a wind turbine and solar panels, so we can stop burning fossil fuels in order to supply our customers with healthy, nutritious salads.

Murky Water, Increased Filtration, Frequent Flushing

Don’t know how you’re faring weatherwise in your part of the country, but we’ve been having torrential rains continuously for the past week or so. The water supply for our greenhouse comes from a reservoir in the nearby mountains, which is open to the vagaries of the weather.

At certain times of year, usually during periods of heavy rainfall, the sediment at the bottom of the reservoir is stirred up and the water that comes out of the tap turns murky. This can easily be solved for your drinking water by adding a purifying filter in between your intake pipe and the faucet. It’s not so easy when you’re running a large greenhouse, with an extensive Nutrient Pond.

We can’t afford to let flow any impurities into our system, since they not only throw off the ppm count, but also tend to clog up the pumps and the system of pipes that circulate our nutrient solution.

Imagine how upset we were when we noticed that murky water was flowing into our pristine Nutrient Pond. My partner and I panicked, but soon regained our usual logical approach and realized that our filtration system had to be upgraded, pronto!

We called our supplier and had him rush over a finer mesh screen for our Y-type in-line strainer that we had installed on our main water supply line. 100 mesh screens normally provide adequate filtration for sediment contamination, but we needed a 180 mesh one on account of the heavy rainfall.

Usually daily flushing is necessary with one end of the Y open to wash out any sediment accumulated in the filter. Under heavy rain conditions, more frequent flushings are recommended.

We also flushed our entire Pond with a weak solution of HyOx, in order to get rid of any unwanted bacteria that might have come in with the sediment. This process also killed off a lot of beneficial fungi, bacteria, and other microorganisms living in the roots of our lettuce plants, which then had to be replaced in the next batch of nutrient solution.

We had to empty our pre-mix and reservoir mixing tanks and clean them out thoroughly in order to get rid of the invading sediment. We had to re-mix a fresh supply of nutrient solution, using Advanced Nutrients Micro and Grow, as well as all our additives, such as the root enhancers Piranha, Tarantula, and Voodoo Juice. These replaced the beneficial micro-organisms that were decimated or even worse by the HyOx flush.

We had to work overtime that day, Chuck and I, and our two part-timers, but we managed to clean our Nutrient Pond and start fresh with a new supply of nutrients and additives. The new 180 mesh screen arrived and was installed and it seemed to be holding its own at the time of this posting.

In horticulture, you never know when emergencies will arise. We’re thankful that we managed this one pretty well and that our hydroponic lettuce production is going full tilt ahead, toward our goal of producing 400 heads of butterhead lettuce per day.

Gardening Advice and Macronutrient Ratios

I was listening to a gardening program on the radio the other day, and the expert on the show was recommending even N-P-K plant foods to everybody. 10-10-10 for some, 20-20-20 for others. Out of curiosity I checked the N-P-K on Advanced Nutrients Micro and Grow, the products that we use to feed our lettuce.

Micro turned out to be 5-0-1, while Grow’s N-P-K is 2-1-6. For non-gardeners, this measurement indicates the percentage of Nitrogen, Phosphorus, and Potassium in your fertilizer. So if I factor in the N-P-K of SensiCal Mg Mix Grow—2-0-0), which is a calcium supplement that we regularly feed our lettuce, our combined N-P-K comes out to 9-1-7. A far cry from what this so-called expert on the radio was talking about.

To educate myself, I called the Advanced Nutrients technical help line. I reached a very knowledgeable man, who assured me that recommending an even N-P-K ratio to the general public is a cop-out. If you do genetic specific testing on the vegetables you grow, you’ll find that each of them has a slightly different need for these basic macro-nutrients.

He went on to say that Micro and Grow are designed to cover a wide array of flowers, fruits, and vegetables. “What if the N-P-K ratio isn’t exactly what my lettuce crop needs?” I asked. “Don’t worry,” he said, “plants eat only what they need. Your combined N-P-K is perfectly adequate to meet the basic needs of any vegetable you may decide to grow.”

He added that if I were growing tomatoes, of course, I would have to add the N-P-K of Bloom, which is 0-5-4, which would bring my combined ratio to 9-6-11. “There is a lot of vagary, where N-P-K ratios are concerned,” was his final comment on this topic.

In terms of the mixing ratio of the Advanced Nutrients 3-part, he said that 1:1:1 works best, although some growers might want to follow the traditional 3:2:1 then 1:2:3 regimen. Whichever proportions you select, Micro goes into the mixing tank or reservoir first, mix it well and wait until it dissolves, then add Grow and Bloom, in that order. Never mix the 3 parts in their concentrated form.

I reminded him that I wasn’t using Bloom, since I didn’t want my lettuce to start flowering and go to seed. He said that’s fine, the 1:1 ratio would still apply.

When I mentioned that my partner and I were using SensiCal regularly in our reservoir, he said that it could also be used at half the strength as a foliar spray. However, don’t spray for a few weeks before harvest, since this process would leave a chemical residue on the lettuce leaves. I said I would rather just mix it in the Nutrient Pond, and stop using it near the harvest end of the pond for a few weeks before harvest.

SensiCal has been designed to provide the proper synergestic balance of Calcium, Magnesium, and the other minerals it contains, which include Boron, Cobalt, Copper, Iron, Molybdenum, and Zinc.