Winter tomatoes; one grower's approach.

[Sequim]

I’ve been growing tomatoes and other vegetables as a hobby for over 40 years, enjoying the convenience of growing in southern California. I have since relocated to the Olympic Peninsula of Washington State where growing is more challenging.

I insist on a continuous supply of home-grown fresh tomatoes but the plants simply can’t struggle through our dark winters, even in a heated greenhouse. So I re-purposed my garage workshop to accommodate a small number of tomato plants with a little room left over for leaf lettuce and other greens.

The indoor growing experience has been the most gratifying of my horticultural career. What follows is a writing about my experiences that I hope you will find helpful, or at least interesting. It is too long for a single post so it will be a succession of posts.

There are other paths to the same goal, some of which may involve better choices than mine. But what I have now works well, and should be a good starting point for other experimenters.

Growing Space (Images 1 and 2)

My growing lab is 24 feet long by 9 feet wide with 9-foot ceiling height. Four feet of the east end is lost to a door from the adjacent garage bay leaving 20 feet for the tomato line along one wall. The active growing area is 16 feet long with a little working space at each end. Taut cables are installed in the overhead for lighting and plant support.

The opposite wall accommodates 20 feet of shelving for lettuce growers and equipment storage. Two 54-inch industrial ceiling fans run continuously to disrupt air stratification and distribute the heat from the lights evenly throughout the room.

The next post will describe what was done to provide electrical power for the lab.

[Sequim]

Indoor growing is energy-intensive. Residential wiring wasn’t sufficient to support the demand of lights, ventilation, dehumidification, and possibly heating. A new 40-Amp load center dedicated to the growing activities solved this problem. Each circuit is ground-fault protected at the load center so special wall outlets are not needed.

Power Switching
Most of the electric appliances must be switched. Lights operate on a fixed schedule but ventilation and pump run times can be more irregular. I found timers to be a cumbersome solution and instead chose two multi-point switched racks. These enterprise-quality devices are used by the thousands in data centers and server farms and are frequently changed out for new models. The discards have many years of life remaining and can be found on eBay for very reasonable prices. Mine are model AP7902, each of which provides 16 switched outlets that can be individually controlled by an internal fixed schedule or manually from a web browser. For special circumstances the outlets can be controlled from any computer on the network.

The equipment that I use to control lighting and other appliances might be a bit too technical for some growers. It is what I’m most comfortable with but not by any means a requirement. Simple timers and manual switches can accomplish the same thing, and in fact that is how I started.

[Sequim]

Artificial light is scarce, expensive, and must not be wasted. Reflective Mylar is stapled to the fixed walls and inexpensive reflective sheets of expanded polystyrene close the sides. Originally all seven of the growers contained plants. Recently all but one plant at each end were removed, making room for more reflection from the bottom.

I have used variations on lighting but found that high quality T5HO luminaires work much better than anything else. I have been experimenting with LED luminaires and believe they might perform even better than T5HO. More on this later.

[Sequim]

Fresh Air (image 1)
A sealed room full of plants quickly becomes unsuitable for healthy growth. Relative humidity must be kept around 65% and carbon dioxide depleted air must be constantly replaced with fresh outside air. Opening a window cannot accomplish this without losing essential heat so I installed a heat recovery ventilator (HRV). This appliance exhausts room air through a heat exchanger, and brings in replacement air through the same heat exchanger. Much of the original heat is returned with the fresh air.

Air Temperature (image 2)
My plants seem quite comfortable when the ambient air temperature is between 75 and 80 degrees. The temperature around the plant canopy is usually several degrees above this. The T5HO lamps and the dehumidifier combined provide more than enough heat to maintain proper room temperature and supplemental heating has not been needed. In fact some extra ventilation is needed during warmer winter days to dispose of excess heat. This is reasonably regulated by a tiny computer on the network that monitors interior temperature and controls the duty cycle of the heat recovery ventilator. The computer, running Ubuntu Linux Server Edition, sends ON or OFF commands to an outlet of the AP7902 switch that controls the ventilator.

Dehumidification
I can honestly declare that you cannot successfully grow more than a single tomato plant in a confined room without dehumidification. My mature plants each transpire more than at least three liters of water in 24 hours. If not removed this moisture will condense on practically every surface in the room and will form puddles on the cool floors. The heat recovery ventilator helps somewhat, but a residential 70-pint-per-day dehumidifier keeps the room dry and sanitary.

Solution Temperature (image 3)
I believe that hydroponic solution temperature must be kept close to 68 degrees Fahrenheit to stimulate active root function and stifle the growth of harmful pathogens. This is not automatic in a growing environment close to 80 degrees. Insulation around the growing chambers helps, but to solve the problem I laid out a series of polyethylene irrigation tubes on the adjacent unheated garage floor to dispose of excess heat. Temperature is reasonably regulated by valves adjusted to control the proportion of circulating solution passed through this heat exchanger.

The next post will describe starting plants for the lab growers.

[attml]

That is a very impressive setup! You have gone to great lengths to simulate natural conditions!! Hopefully your hard work will payoff in the flavor of your harvest!

I used to keep live saltwater coral reef aquariums and we would setup lighting, cooling, flow filtration, etc. systems to make as close as possible conditions to what would be on a coral reef. If you scroll down in this thread you will see what I am talking about (the equipment is near the bottom of the page) http://reefkeeping.com/joomla/index....k-of-the-month

Nice work!

Mark

[Cole_Robbie]

Yes, very impressive, especially the electronics.

It might also be neat to experiment with red plastic around the tomatoes, like the stuff that is sold as plastic mulch. I'm not a big fan of mylar; it's easier to just make everything flat white.

Thanks for posting about your setup.

[Sequim]

Plants intended for hydroponic growing should be kept a little cleaner than those destined to grow in soil. I’ve tried rock wool cubes, peat pellets, coir pellets, and several packaged mixes, but eventually fine-tuned the following method.

Important Note: Work with your plants indoors only. Never take them outdoors. Doing so will put them at risk of pest infestation, such as greenhouse white fly. Pest infestations on outdoor plants can be somewhat self-regulating with help from predators and the pests’ inclination to move from one crop to another. Pests captive in an indoor growing lab cannot depart, so an infestation is catastrophic.

Planting
My favorite media is pure, fine, horticultural grade vermiculite. Steps 1 through 3 are performed before water is added. This makes it easy to level the media surfaces.

1. Fill cells of a plug tray 1/8 inch less than the desired finished depth. An extra cell left unplanted is helpful to accommodate a temperature probe.

2. Place up to three seeds on the surface of each filled cell.

3. Cover each cell with at least 1/8 inch of media. If less is used the seedlings might have trouble shedding the seed husks from their cotyledons.

4. Place the plug tray into a shallow container and add tap water that is pH-adjusted to 6.5 and temperature about 65 degrees F. Do not add any nutrients.
Within seconds the water will be absorbed upward into the cells, thoroughly moisturizing the media.

Image 1 shows Step 2 for my current winter crop. The upper row of Bella Rosa are clearly-visible blue coated seeds (coated seeds are not Thiram-treated seeds) left over from last winter. The Sun Gold and lower row Bella Rosa seeds are uncoated and circled to help you find them.

Incubating
Place the plug tray into a heated sprouting chamber with a clear cover. Regulate the media temperature between 75 and 80 degrees F. Be prepared to remove the clear cover and flood the cells with fluorescent or LED light as soon as signs of emergence are noticed. Sustain the light, overnight if necessary, until most of the plants have emerged. Try to prevent any plant from emerging in darkness. Monitor the media temperature to assure that the added light does not overheat it.

Early seedling care
When most of the seedlings have emerged, schedule about 16 hours of daily illumination. Try to maintain the ambient and media temperature between 65 and 75 degrees. If you notice some bright sunlight entering through a window, move the tray into it for a dose of natural light.

The seedlings may need water added daily. Continue to use pH-adjusted water but do not add any nutrients.

The first true leaves should be evident within 12 days from planting. This is the signal to move the seedlings into their first growing stage. I’ll cover this in the next post.

[Sequim]

Thank you Mark, and thanks for the reef aquarium link. Reef aquariums are gorgeous.

I'm interested in some of the lighting techniques used for reef aquariums, particularly the actinic tubes. I think there might be a match with a lesser peak of chlorophyll pigments. I have some of these tubes and hope to someday find a chance to experiment with them.

Pete

[Sequim]

The electronics actually help a lot, but the main reason I use them is because I'm a devoted nerd and just can't help it.


Pete

[attml]

Pete,

In aqaurium lighting a lot of metal halide (6500K to 20000K) are used. The 6500K were more on the yellow end of the spectrum. They produce fair coral color but due to their PAR value were best for coral growth. 10000K were more of a white light and they produce good color and good growth. 20000K were more of a blue tint but produced the most beautiful coloration in the coral but slow growth. Power Compacts and T5 lighting are use quite a bit also. Here are a couple of decent articles as lighting as it applies to reefkeeping but there may be some decent inforation that you might be able to apply to your setup. Good luck and keep us up to date with how your plants are doing

http://www.advancedaquarist.com/2002/10/aafeature
http://www.advancedaquarist.com/2003/3/aafeature

[Sequim]

Day 11: October 2, 2012
I’ve always transplanted the seedlings to 3-inch net cups to minimize lighting space requirements. Later they will be again transplanted to 6-inch net cups and will require more growing space.

All transplanting work is done submerged in water to minimize damage to the seedlings. Transplant events are pre-scheduled with my wife so I can have full use of the kitchen sink (Image 1).

Isolate the seedlings
The plug tray is immersed in water to loosen the vermiculite (Image 2). A dinner knife or similar tool is helpful to gently lift the root mass out of each cell so the seedlings can be separated and their roots rinsed free of vermiculite. Entangled roots can be easily and safely separated when submerged. The bare-rooted seedlings are arranged in a fresh bowl of water, segregated by variety (Image 3).

Re-plant in net cups
Each seedling is planted in a 3-inch net cup with all of its stalk buried in the media. A dinner fork is helpful to keep the seedling centered as the media is distributed around the stem and roots (Image 4). Media shown is Hydroton, a fired-clay product from Germany that has been available for over 20 years, but was discontinued in mid-2012 when the clay mine became depleted. I have a large supply of it and also recycle it between crops.

Move to the growing environment
The net cups are placed in the grower under lights (Image 5). This is the seedlings' first exposure to nutrients and they will quickly begin vigorous growth. Nutrients must be very mild with low nitrogen content to restrain their early growth. The plants should grow much wider than they are tall. They will be ready for the final transplant in about eleven days, and this will be the subject of the next post.

[Sequim]

Day 23 (October 14, 2012)
The seedlings have 12 days of vigorous growth since the first transplant (images 1 & 2). They are healthy, strong and stout with width at least three times their height. They must be moved to larger net cups before their root masses become too dense and entangled to be safely removed from the 3-inch net cups. This will be their final transplant.

The final transplant
The seedlings must be carefully removed from their net cups and planted in larger net cups (images 3 through 6). As before, all the work is done submerged in water to avoid inducing shock. A dinner fork is helpful to gently comb tangles out of the roots.

Only the strongest are chosen
Each transplant event begins with more seedlings than can be accommodated in the grower. This time only 12 of the 18 seedlings will be selected; six in each of two growers (image 7). If this were a spring planting there would be plenty of good homes for the orphans, but sadly there is no one to adopt the plants with winter coming.

In six days the seedlings will outgrow the limited space and will have to be moved to their permanent home in the growing laboratory. This will be the subject of the next post.