Thus begins the year that we start from scratch. The past 2 years have been disappointing, to say the least, and we're determined to find a setup that works. So off we go to Growking, our local hydroponics store, to create a system out of parts and nutrients made specifically for this purpose - no more gutter and buckets. Indeed, buying specially-designed equipment is more expensive, but, as we now realize, things can be made as simple (and cheap) as possible, but no simpler. We have great faith that others successfully grow gorgeous and abundant veggies using things like rain gutters and recycled fish water, but since we have not figured out how to make these work for us, we move on (for now : )
We live in the woods, so often end up sharing our greenery with the local
critters - usually finding things like peas and lettuce mowed to the roots.
Also, our floor is a bit uneven. So Pat made a raised, flat table out of
lumber scraps, to provide a flat surface for the new trays and keep our
tasty plants further away from the rodents. Now, this didn't keep them
from being munched, so Pat then made a ledge out of pieces of Corrulite (which we happen to have lots of) that
sticks out away from the wood structure, which, it turns out, does actually
thwart them. (You can see the thin, white sheets just below the plant
trays.) The table is angled just enough to allow the nutrient solution to
gravity-flow at a reasonable rate. The other plants scattered around in
pots are just dirt-potted plants being saved from the unusually frequent
frosts this year.
Now some specifics about the system. Growking custom-cut the trays into 8' lengths with holes for pots every 8". 3.5" plastic mesh pots are in each hole, and the plants, started in small Jiffy peat discs (the little flat ones that puff up into marshmallow-looking things when soaked in water) set into each pot. For several reasons, we chose to surround the peat with lava rock left over from the old system: It would provide a bit more stability for the plants once they got bigger; give some extra purchase to any roots that sprung from the sides of the peat; provide some more shade and a bit of moisture-retention to the roots; and let the nutrient solution pool just a bit around the small roots of the young plants as it flows by.
Nutrient solution gravity-feeds from the right side of the picture and
pours out at the left side into our old rain gutter from spouts inserted
into the ends of the trays.
Then the nutrient solution keeps gravity-feeding down the gutter and back
into the reservoir. Inside of the reservoir is a water pump as used in
fish tanks or ponds that pumps the solution back to the top of the trays.
But before it gets to the top, the solution passes through a filter
apparatus that strains out silt and other large particles. These filters
can be found where 1/2" irrigation tubing and supplies are sold.
After being filtered, the nutrient solution fills and pressurizes the white piece of tubing seen attached to a wood beam on the left. The pressure forces solution into the black irrigation lines, which are inserted into the end cap of each tray.
We started running the pump for 15 minutes every 2 hours during the
daylight hours in Dec/January. In February, as the days began to warm, we
ran the solution for 8 minutes every hour, from 9am until 4pm. This seemed
to be often enough to keep the roots well hydrated and aerated, and the
plants seem to be getting an adequate amount of nutrition. Those hours are
based on the greenhouse only getting sun from around 10am through 3pm, and
the sun setting around 5:30pm. As the days become longer and hotter (and
depending on how the plants are doing and our own curiosity) we'll adjust
the number of runs per day and how long each run lasts. As of March 12, we
switched to 8 minutes, running every 30 minutes, since the lettuce was
beginning to wilt in between waterings. Commercial NFT systems often run
their pumps constantly (at least during the day.) I'm not sure if we'll
have to do this or not, but if so, the plants will let us know.
As a winter crop we're currently growing peas, lettuce, spinach and cilantro, all of which are doing extremely well, especially compared to the same types of veggies grown in the hydro setup's previous incarnations. Here's a picture of them when they were more mature, and as of mid-March, they've probably doubled in size again.
We change the nutrient solution every 2 or 3 weeks, and since it's organic i'm happy to feed the waste water to the plants in my yard, and they love it.
To start with, we're using the amount of nutrient recommended on the label. At the 17th Annual Conference of the Hydroponic Society of America, Pat heard Anthony D.M. Glass talk about experimenting with using fractions of the recommended amount. He found that lettuce did as well with 1/10th and 1/100th of the recommended levels as with full strength, and that tomatoes did as well with 1/2 and 1/4th of recommended. So we're intrigued by this and might do a similar experiment, once we're happy that the setup is successful.
Also, i've been told by a hydroponic nutrient developer that organic solutions don't work as well in bare-root NFT systems as they do in systems where the plants' roots are in a water-retaining medium of some sort, like perlite, peat moss, or the 'soilless' mixtures sold in hydro stores. Organics aren't as broken down and are less bioavailable then their synthetic counterparts, so if they don't have something to stick to and break down in, it's harder for the plants to reap their nutrient benefits. But synthetics are made to be extremely bioavailable without needing to further break down. Maybe the mature plants' root mats can provide somewhat of a substrate for this breakdown to occur, maybe it's not adequate. Personally, we very much believe that it's healthier all around to use organics, which i also practice in my dirt gardening. So if we get a bit less than the (amazing!) theoretical maximum yield from our plants, that's a fair tradeoff as far as i'm concerned.
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