Monthly Archives: August 2013

One of the three amigos
(lettuce in rockwool cube)

It is probably a little late, maybe a few days, but today the plants went into the nursery channels (built here).

Lettuce roots growing thru the rockwool

You can see the little guys are growing nicely, and they’re pushing roots thru the bottom of the rockwool.
The rockwool is pretty porous (you never squeeze it, as it’ll compact down into a small ball then), and has a fair amount of air-space in the cube.  This allows the actual material to suck up water, but the roots still have alot of air pockets in there to get oxygen.  If you simply submerged the entire thing in water, the plant would actually drown (unless you had highly oxygenated water, which I don’t plan to do) .  Swim little guys, no drowning here.

Basil triplets

Basil in rockwoll, in a net pot, in a nursery channel

To move these guys through the process, we break apart the rockwool cubes. They’re 1×1″ cubes with a slight taper to the bottom, which makes inserting them easy-going into our 2″ net pots.

If there are any long exposed roots, they can be fished thru the net pot openings. But, they plants are smart and will do that on their own.

It is hard to see in this picture, but the bottom 1/8″ or so of the netpot (and corresponding rockwool) is just beneath the water level.  This encourages the plant to grow roots down.  We need about 1.5″ of downward root growth before planting in the finishing channel.  This is because the finishing channel is a true nutrient film technique system, which means the channel only has a film (1-3mm) of nutrients flowing under the plant, so the plant’s roots have to reach down there to suck up the good stuff.

Nursery channels full with basil

Here are two nursery channels. Note the close spacing. The plants will quickly outgrow and crowd themselves if left here too long.  Hopefully they will be ready to move out into their larger accomodations (finishing channel) within a week or two.

The plants (41 basil and 3 lettuce) are under 16hrs of light per day and nursing a light nutrient mix.  In a few days, they’ll get another hour of light and a stiffer cocktail.

Basil under lights

Today is one day short of 3 weeks since the first round of seeds hit the dirt (figuratively speaking, they hit the rockwool really).

The original lettuce is 96% a disaster. The only lettuce plants that look decent are two seeds that were late bloomers – they didn’t germinate until I realized they needed full light and water so soon after germination.

The leggy lettuces are doomed, I think. I removed 12 of them tonight, and reused the rockwool for 12 new bibb lettuce seeds.  The new plan is to germinate them, see the sprouts, and immediately go into a 1/3 or 1/2 nutrient solution and full 16hrs of light.

The three amigos are doing well. They are in the lower middle here:

Today I realized the bibb lettuce is just not going to stand up.  It hasn’t improved much.

To get some more data points, I pulled 3 leggy plants and put them to rest (ate them, quite good. I’ll do an article on micro-greens soon).  I reused the rockwool for 3 new bibb lettuce seeds. They’re hiding in the dark and chilly room (well, 71f floor temp) of the basement.

The living received their first non-water feeding. They received a well-balanced meal of 750ml of nutrient-filled PH-balanced water.  Mmmmm-mmmm good!

And, of course, they’re still under lights. Just about 1″ under a 2′ T5 setup.  The oscillating fan and basement temps keep the rockwool about 73-75f during the day, creeping down to 70 in the early morning hours.  They’ve been increased to 16 hours of light, from around 12 they were getting.

Basil at 11 days. We lost a soldier due to non-germination.

This basil is looking pretty good!

Bibb lettuce at the same age. Very leggy.  In hindsight, the cause is now obvious.

Here, we’re building a prototype hydroponic nutrient film technique (NFT) farm.  The goal is to be able to have a constant harvest of 20 plants per week. This requires 20 plant sites (at least) to be available to each phase of the growing cycle.

How to begin?

A lot of graph paper. And some time.
Then, basically, I went and got a bunch of pipe and tubing, combined it with pumps, aerators and valves. That was the easy part. Figuring out the design, how things (water?) flow, channel, wave and suck (believe those are all technical terms) was the hard part.

It isn’t just building something that will make the plants happy – a good system requires ease of maintenance as well.  Floor level drains, easily accessible valves, standard fittings to fill/drain reservoirs, and simple things such as black-opaque tubing to keep algae growth down is necessary.

Channels

This is a nursery channel in construction.  The nursery channel is a high-density NFT-like (nutrient film technique) channel, but it really doesn’t entirely use NFT principles.  The nursery is the step following the seedling tray stage.  It allows the plants to expand their roots in a more efficient condo-style accommodation, until they are ready to plant in the finishing channels.
This nursery channel is 5′ long and has 23 plant sites.

Here you can see two nursery channels adjacent to a finishing channel.  The finishing channel has about 10 plant sites to the nursery’s 23.  It has to be further spaced to accommodate the growing plant.

One light installed above the nursery channels.  This is a 4′ long 4-bulb T8 housing.  It will provide light for just over half the lower nursery channel.  The upper section will be another 4′ housing that will provide seedling and nursery light.  All the lights are on height adjusters, they start very close to the plants and move up with them.

The longer-term goal is to have the channels on adjusters as well, in order to stack multiple channels and lights atop each other to maximize the growing capacity for the available floor space.

The nutrient (water + fertilizer) reservoirs are shown here, as well.  The lower (right) is where the pumps (water and air) reside.  The nutrient-filled water is pumped up with one tube into the upper reservoir, where it is then distributed to the growing channels.  Excess water in the upper reservoir is returned through the other black tube.  This allows the pump to run at maximum capacity (greatest efficiency and less wear) all the time, while any excess capacity at the top is simply gravity-drained back into the reservoir, further adding oxygen and preventing stagnant water.