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Starting seeds in coco coir?

Posted by hydroangel Boston, MA (My Page) on
Thu, Feb 19, 09 at 4:33

Hey guys,

I'm planning on starting my lettuce seeds up soon for my DWC system. I got myself a coco coir brick and I'm planning on putting some in small pots, placing them in a mini-green house, and letting them grow enough roots to put in the system. This would be my first time starting in coco coir, previously I have started with the jiffy plugs, and want to make sure I'm doing it right. Also, once they're rooted, should I just put the coco coir and the plant onto my hydroton filled net pots, or should I just transfer the plant? I also want to see if anyone has mixed the hydroton with the coco coir as a medium, and if so, how? Mix it all around? hydroton on top, coco coir on bottom? Any other type of combinations? Any help is appreciated.


Follow-Up Postings:

RE: Starting seeds in coco coir?

Not sure the reasoning for using coir in a DWC setup... You can use just plain hydroton if you are careful with seedlings. Jiffy pellets are fine, rockwool cubes are commonly used as well. After the seedling is established the water and nutrients come directly from the water and the medium is really just to give the plant stability.

My hydroton is almost complete dry after the plants are established as I lower the water level a bit. Not sure even if you had coir mixed in that it would matter or add benefit. More than likely it would fall out of the hydroton (if water was close enough or top watered in the beginning) and would help to clock air stones and or pumps.


RE: Starting seeds in coco coir?

Here's a neat trick for starting seeds:

Using a 72-hole platic germination tray, stick a small clump of fiberglass wall insulation inside each cell and get it wet. I use nutrient, but water will also do the trick.

Place one seed in each cup and place the entire set-up in a 10 x 20 propagation tray with about a 1/4 inch nutrient puddle of EC about 1.2 in the bottom. Cover with a clear dome and place it in either dark or in the light (depending on cultivar -- some need light to germinate).

After about 3 days, you should have little plants showing and after a couple of weeks, you can just take the wad of insulation, roots and all and transplant that to your DWC net pot and let it rip! The insulation is inert.

Another method is to use perlite in a 2" net pot and place the seed right inside the pot. It will germinate there and as soon as you have white roots shooting out the bottom of the net pot, transfer it to your DWC set-up and you're rollin'! There are pictures of this method on my Web page in the Gallery (URL is in my profile)

RE: Starting seeds in coco coir?

Hi freeman,
? When direct seeding in net pots do you need to use sifted perlite fines or pay any attention to maximum size of the perlite granules ?

RE: Starting seeds in coco coir?

I use polyurethane foam to start my seeds, I recently made a post about it in my blog (which you can access using the link below) I hope it is useful !

Here is a link that might be useful: Everything Hydroponics

RE: Starting seeds in coco coir?

Noticed you later asked about plugs. I recommend them over anything else if you use a compost bin to get rid of your spent plants. Fiberglass won't compost. Rockwool won't, either. But, if you have old fiberglass lying about that is a great way to reuse before trashing the stuff. I may just have to do that myself since I'm reinsulating parts of my house. Anyway, I'm all about ease.

I've used coir quite a bit as medium. I mix it with perlite and top it off with hydroton. That's what I use in the hydrofarm-like set-ups I've found to be the most successful for peppers and tomatoes. The coir/perlite will keep you from having to worry about dry conditions as much as it will hold lots of water. That way, if your water runs low while you're away or being lazy (the case with me occasionally) you don't lose your plant in a day or at least damage it's processes. The hydroton helps to keep the water from being wicked onto the stem. You'll notice the pics with the worst infections around a stem seem to have a wicking medium (especially the case with rockwool) all the way to the top of what would be the soil line in a garden environment. Some people on here have suggested river rock and even those glass pond rock things you find in glass jars for decoration.

RE: Starting seeds in coco coir?

I'm starting tomatoes, peppers, lettuce and parsley in coco starting pods (fibergrow/planterspride)with surrounding hydroton. The paper wrapping seems that it might block the roots as they form. Time will tell as they sprout. I'm game for any other materials to start the plants in. I'd like to try poly fill that's used in fish filters. It may not wick very well. Some Fiberglass insulation has formaldehyde and fire redardents, so that should be avoided. Polyfoam sounds interesting and I would like to hear more about that. I want to keep the cost down and avoid special items like rockwool cubes that go for $14.95 a tray.

Here is a link that might be useful: Aeroponic system photos

RE: Starting seeds in coco coir?

Hello Botsmaker,

I have always done my germination and first growth phase in polyurethane foam it is a great and extremely cheap substrate for germination. However after two weeks you should cover the foam cubes with media and put the plants within their next stage or final location since the cubes start to become very favorable for algae growth as you increase the strength of the solution. The high capillarity of polyurethane foam can be thanked for that.

I also advice you use this foam for systems where the foam will not be in contact with water all the time as this has in some cases caused fungal disease due to the very high humidity levels (and eventually low oxygen levels) within the foam. Systems that use drip irrigation or ebb and flow techniques work great.

I hope this helps you decide :o)

Best Regards,


Here is a link that might be useful: Everything Hydroponics

Growing in coco coir?

Coco coir/peat is the best alternative to mined peat moss. Coco coir is a proven natural alternative to mined peat moss, therefore, using it helps slow down peat extraction from environmentally sensitive swamps world wide. Used as a growing medium/potting medium coco peat out performs most of the popular brands of peat and sphagnum peat.
High water holding capacity
Acceptable pH & EC
Excellent wetability, superior to peat
Ability to retain nutrients against leaching and to buffer supply
Unique water holding capacity
Good drainage / aeration
Less shrinkage
Retains physical properties longer
Light weight

Here is a link that might be useful:

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