Aquaponic Gardening

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Until recently all the work at Coastview Aquaponics has done by our family. Our farm has grown in size and has evolved over the last year. We have improved on the efficiency of our day to day work to save us labor/time. During the evolution of our farm we have constantly been improving on techniques that we have learned. One of our improved techniques is our new seeding process. We have been using this new seeding technique since October 2010 and it has proven itself well over multiple harvests. Now that this technique has proven its self we think it is time to share.

 We used to use a coconut & vermiculite mix in 2" net pots that were placed into 32 cell starter trays. This worked OK for us but we had a poor overall sprouting rate. Sometimes the seeds would sprout then die once touching the coir.  Sometimes we would have a bad block that would not sprout anything at all. We later learned the coconut was imported from overseas.

 

Here is an example of poor germination with coir mix. Every cell was planted at the same time and only some of them came up.

 

 

 

 

 

 

 

 

 

 

We began experimenting with alternative medium for seed sprouting. We tried many different mediums and had the best success with black volcanic cinder. This medium is local produced and readily available when living on an active volcano.

Black volcanic cinder is as light as hydroton if not lighter. Lots of it will float if filly flooded. Cinder is very porous and has more surface area than standard gravel. It has excellent wicking capacity in 2" net pots. The cinder is very easy to recycle and use again.

The cinder from the quarry is very dirty with lots of fine material mixed in with it. We screen and wash it to size grade and to remove the sand and silt. The larger cinder is used for gravel beds and the small cinder is used for seeding. The sand/silt is used in our wicking bed medium.

We now use our newly developed technique of seeding net pots directly into our sprouting rafts(2'x2'w/ 61 holes) using cinder as the sprouting medium. We line up 4 rafts at a time, insert net pots, then pour the cinder over tho top of the rafts. Using a small hand broom we broom the cinder into all the net pots and then broom off the excess.We are able to fill 4 rafts(244 net pots) with media in less than 10 minutes.



 Previously we seeded net pots in sprouting trays that would be later transferred into the same rafts after 7-10 days. We now eliminate the labor of transferring from sprouting tray to raft which saves us hours a week. We have shifted away from pelleted seed to using conventional seed(mostly grown by us). Raw seed tends to fall into the voids in the cinder to a perfect depth. The cinder has a wicking capability and if the bottom of the net pot is sitting in water then the seed on top will have adequate moisture for germination without rotting issues. The roots of the plants have all the oxygen they need in the voids of the cinder and grow very quickly.


 

Seeds germinating out of direct sunlight. I cover with plastic to keep them from drying out. After a 3 day germ I move them to one of the sprouting tables.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We germinate the seeds our of direct sunlight for 3 days. By then the first seeds are looking for sun and I move them out to the seeding tables. We made custom seeding tables so that they would hold 8 sprouting rafts at 2'x2'. The tables have a constant 1" of water flowing through to provide fresh nutrients to the seedlings. These tables are like a thick NTF table. After two weeks the roots are long enough to need more water and we move the rafts to the nurcedry trough to make way for the next batch of seedlings.

 

These rafts are floating on 1" of water in custom sprouting tables. This table is a thick NTF table. The sprouts stay here for 2 weeks. We have 2 of these tables.

 

 

 

 

 

 

 

 

 

 

 

 

Here is out nursery trough. The plants grow in here for 2 additional weeks. They then move to the grow out troughs and get spread out to a grow out spacing.

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Replies to This Discussion

With pelleted seed you need to use then up in a short time. They will loose their viability within a year. Johnnies sells packets of 200 pellets then it steps up to 5000 for the next size up. It is difficult for me to use up 5000 seeds before they go bad but 200 pellets do not last me very long. I grow 6 varieties of lettuce and if I order 5000 pellets of each there is NO way I can use them all up before they go bad. Conventional seed will last much longer and is way cheaper. It is smaller and harder to handle but I now prefer it. When using cinder or other similar media the conventional seed will fall into the cracks and plant itself. I now grow much of my own lettuce seed and it will germinate quicker than seed that I purchase because it is fresher. If you purchase seed from a local source like Wally World of the Depot it is VERY important to look at the date on the back of the pack. Do not buy last seasons seeds. Do not buy seeds stored outside of in direct sunlight which I have seen at a local big box store.

Hi Chris,

I grew-out a bronze lettuce variety to seed and harvested the seedlings yesterday. I haven't planted any from these seeds as yet. I'm following your experience here. I'm wondering, does the plant from these seedlings hold the same characteristics as the original plant? Do they grow the same way/time as the original?

Lettuce is self pollinating.  If you have one plant isolated it will produce seed that will be duplicates of its parent. It can be cross pollinated by other varieties if they are seeding at the same time and in close proximity. I am actively trying to come up with my own varieties of heat/disease resistant crossbreeds by allowing desirable varieties to seed right next to each other. Bugs and wind should help to cross-pollinate them. Here is some good info on seed production:

http://ofrf.org/funded/supplements/colley_08s27_OSA_Lettuce_Seed_Ma...
I've grown out a lot of romaine and some other lettuce varieties out to seed as well, recently started planting the ones I've grown. I don't use pelleted seeds anymore either. I find it not to be worth the extra expense. I haven't had many germination issues with the coir/perlite mix. What I have noticed is a powdery mildew problem, probably due to being too saturated. I don't understand how others aren't having that problem. Since I'm running out of the last of the coco coir, I think I may try the expanded slate again..I have a lot of it and it's small enough not to fall through the net pots.

Chris,

I just realized that with your pumice/seedling-raft technique a separate sprouting table and nursery trough are unnecessary.  As long as you can afford the space, it would be a simple affair to float seedlings at the end of a trough.  You could setup a short section of framing over the trough for extra shade cover.  Harvest a raft of mature plants from the opposite end...insert an empty adult-spacing raft between the last seedling raft and first adult raft....then move seedling pots from the seedling raft to the adult raft for final grow out.

??

Averan I think you are missing Chris's point. He is at capacity in his rafts. He developed the seed tables because his rafts are in full production. In Chris's world every raft is dollars so maximizing space the way he does is the best return per sq ft. Which is the way you should run a raft operation. IMO putting seedling in a raft to take up growing space is foolish because of the wasted space of the net pots that dont germinate. The raft should only house nets that have viable product to sell.
In response to Averan's point, I have read that there is also the possibility of the moisture being too much for the young roots from the sprouted seeds ultimately leading to them rotting.

Thanks David....I had not missed his point at all and fully understand why it was necessary for him to take the approach he did.  My point was that there may be other situations/layouts where my suggestion would work better.  A raft of seedlings is going to take up space somewhere.  And it is going to use sunlight and water.  Instead of building an entirely separate structure in its own area with its own plumbing to deal with, one could simply dedicate a portion of their growing troughs to seedlings.  Germinate your pots somewhere else first like Chris does, then put the fully sprouted seedling raft in the trough.

Nigel, if that were true, then Chris' technique would not work:  "The tables have a constant 1" of water flowing through to provide fresh nutrients to the seedlings."  1 inch or 12 inches, the depth doesn't matter to a seedling.

Hi Nigel,

Looks like Chris is one up on us here. If i were to have constant water flowing into my coconut husk of seedlings they will rot for sure.The cinder wicks while the husk retains water. Chris is using the ideal media for his raft(availability,cost,use etc). Makes me want to pack up and go to Aloha land!!!


Nigel Clement said:

In response to Averan's point, I have read that there is also the possibility of the moisture being too much for the young roots from the sprouted seeds ultimately leading to them rotting.

I have accidentlly left out a few inportant details of my seeding technique that is now being questioned. When seedlings have sprouted they need little room for the roots. Instead of putting seedlings that have little root mass into my 12 inch deep troughs I elect to put then into my specially built sprouting tables. These tables have a constant 1" of water to float the rafts and keep fresh nutrients supplied to the seedlings. These tables are elevated which makes it much easier to remove double and triple seeds in a net pot that germinate. After two weeks and removing extra seedlings I move them to my nursery trough. This trough is 8 inches deep. Eight inches is not enough depth for optimal grow-out of most plants in aquaponics. I use this trough for young plants to have more room to grow than the seeding trays.

When I harvest plants out of my grow-out system I can replant the the rafts with juvenile plants from the nursery trough. By the time I move plants form the nursery trough to the grow-out system, the roots of the juvenile plants will soon be needing more room to grow than 8".

I live on a steep volcano and have little flat space. I utilize the flat space for the grow-out system and use the other space for everything else. If I have lots of flat space, I would have seedlings introduced at one end of the system and use a constant 12" of trough. The plants would go into the trough a one end then grow and be harvested at the opposite end of the trough. I would have a mirror image system on the other side of the first system so I am harvesting out of a common harvesting isle and seeding on the outer edges.

You are correct David, I maximize my 12" grow out space by placing established plants into it. My seeding rafts have some duds and that is to be expected. I hedge my bets by dropping 2 or 3 seeds into each pot. If I get doubles or tipples that germ I can easily remove the extra seedlings at a good working height before placing the rafts into the troughs.

David Waite said:
Averan I think you are missing Chris's point. He is at capacity in his rafts. He developed the seed tables because his rafts are in full production. In Chris's world every raft is dollars so maximizing space the way he does is the best return per sq ft. Which is the way you should run a raft operation. IMO putting seedling in a raft to take up growing space is foolish because of the wasted space of the net pots that dont germinate. The raft should only house nets that have viable product to sell.
My current seeding operation has gone through quite an evolution over the last couple of years. I am constantly trying to improve on the process. I am posting what works for me right now. I may come up with a better idea next week which will take months to provide data on and make me comfortable to post to the community. I do not post anything that I have not actually tried and proven to work in my systems. I am just trying to save you the learning curve that I went through! If you do not think my techniques are good, please show me something better (that you have proven by actually doing it) and report back!!

Averan said:

Thanks David....I had not missed his point at all and fully understand why it was necessary for him to take the approach he did.  My point was that there may be other situations/layouts where my suggestion would work better.  A raft of seedlings is going to take up space somewhere.  And it is going to use sunlight and water.  Instead of building an entirely separate structure in its own area with its own plumbing to deal with, one could simply dedicate a portion of their growing troughs to seedlings.  Germinate your pots somewhere else first like Chris does, then put the fully sprouted seedling raft in the trough.

Nigel, if that were true, then Chris' technique would not work:  "The tables have a constant 1" of water flowing through to provide fresh nutrients to the seedlings."  1 inch or 12 inches, the depth doesn't matter to a seedling.

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