how to use rapid rooter plugs with seeds

Starting seeds in Rapid Rooters?

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I don’t have good luck with germinating seeds or keeping them alive long enough to grow out. Most of my failures have come in the first two weeks so I am modifying what I normally do in an attempt to get better results.

My new plan is to use rapid rooters and just place the seed in them, then place the RR in a seedling tray, put 1/4″ of water in the bottom of the tray, put on a humidity dome and put all of it in the dark.

The temp in my closest varies from about 80-85*F and the relative humidity is 66% without the humidity dome. The RH jumps to 85% RH with the dome on.

Is 85*f and 85% RH too high and could this cause fungus problems? Is 66% high enough given the fact they are sitting in a 1/4″ of water?

chuck estevez
Well-Known Member
Well-Known Member

Sounds like a recipe for cooking rotten seeds.

Don’t use a dome with seedlings, 66% is fine, so is 40. Seeds and seedlings do not require high air humidity level. And don’t put the rapid rooters in a layer of water. Instead add a layer of perlite or hydroton, put the rapid roots on those and water them. Try to keep the temp below 80.

I too soak seeds in (warm yet cooling down) water for 12-24 hours before planting them.

And place them under light.

Well-Known Member

That’s a brilliant idea! I will do just that.

I read two different versions. Some same put the RR in the dark to germinate and others say put them under light. Even the Rapid Rooter tray instructions say to place them in the dark to germinate.

Why is light so important when the seed is under cover anyway?

Well-Known Member

Even though your temps are 80-85f in the space the wet RR will be colder and it will likely fluctuate. Putting light (not too strong, I use T8 ) above it helps keeps the temps in the RR stable. But besides that, if you’re already have a hard time germinating, they will likely not all pop the same day and seedling that grow up in the dark become stretchy and lanky (searching for light) fast.

Soaking them addresses both of those issues. If germination fails from improper environmental settings it’s usually shortly before cracking open (too much water, not enough oxygen, and/or too cold/warm) or when it just cracked. The longer that takes, the riskier it gets and the more important it becomes that the environment remain stable. Ideally you measure the inside of the RR for a complete day.

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while the inside was 75

Well-Known Member

while the inside was 75

My first grow was a fist fight that I lost. I was smart enough to grow more seed than I needed and finally figured out what I needed to know enough to grow and harvest a few plants. I feel like if I can get my plants to live to two weeks old, I think I’ll have a good chance at finishing them.

I’m been trying to practice on bag seed and not having any luck germinating. I’ve order some expensive seeds and ready to try to germinate them but nervous they won’t germinate.

I’ve tried the paper towel method a couple of different ways and that bag seed didn’t crack. It could be just bad old seed but I’m not sure it’s not at least partially my method.

I’m thinking as soon as the seeds break the surface in the rooter, to plant them in a cup and move them to the tent under CFL’s at 12/12. The rooter won’t sit in the seedling tray for more than a day after they break the surface and won’t grow roots out of the rooter before they are moved.

First, I have to get them to germinate without growing fungus. Sativied’s idea of putting that rooter on top of a bit of perlite wicks the moisture up without saturating the rooter is a great idea. I am testing that right now to see what kind of moisture the rooter will hold and for how long while I wait for my seeds to arrive.

If you guys say put lights over the rapid rooters to germinate, I’ll do it, but it seems counter intuitive to me if seeds need dark to crack.

I don't have good luck with germinating seeds or keeping them alive long enough to grow out. Most of my failures have come in the first two weeks so I am…

Xlr8’s seed germination technique: Germinating in Rapid Rooter plugs

  • Jan 7, 2013
  • #1
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    My seed germination technique

    I really like Rapid Rooter plugs. I’ve been germinating seeds in them since I started growing, and now use them for cloning, too. They’re great as they can be used to germinate for soil or hydro, and easy to use. They contain important micronutrients and beneficial organisms to stimulate rapid root development. They have a really nice balance between moisture retention and airiness.

    Here’s my process:

    I soak seeds for a few hours in a glass of RO water. The Rapid Rooter is soaked overnight in a glass of RO water.

    Making sure my hands are clean and sterile, I shake the excess moisture out of the rapid rooter, or give it a gentle squeeze. Basically, you want them to be “moist” but not soaked/saturated.

    I take a sterile tweezers, squeeze it together, and I stick it into the hole of the rapid rooter while I gently twist it around some. I’ve had better luck if I deepen the hole slightly, and loosen it up a little inside the rooter plug. You could also use a pen, etc. Basically, just loosen it up and make it about a 1/4″ deeper than they come from the factory.

    I use a clean pen cap as a tool to scoop the seed from the cup of water, and place it into the rooter. I used to do the “paper towel” method of “pre-germinating” seeds, but it is better to plant them directly in the rapid rooter (or whatever medium you use). You will have better success, and quicker development if you skip the whole paper towel thing, in my experience. When putting it into the rooter plug, I put it in pointy end up (hinged end down). Positioning it this way will allow the taproot to make the turn it needs to, and will put the seed in a better position to succeed and remove it’s “helmet”.

    I place the seed about half way down into the rooter (again pointy end up) and then I tear a small piece of rooter plug to cover the hole on the rooter. It should not be “jammed” in there, but placed in somewhat loosely. The hole should be fully covered to not allow light in.

    I place the plug in a humidity dome, under t5’s. I don’t use a seedling heat mat (only for clones and not directly under). I mist the dome periodically, but high RH isn’t needed to germ seeds. The rooters shoudn’t be allowed to fully dry, and should be moistened periodically with plain RO water.

    • Pre-soak seeds in glass for a few hours
    • Pre-soak rooter plug 12-24 hours (probably doesn’t need to be that long)
    • Use RO water from store – do not PH balance it
    • Shake/squeeze out excess moisture in the rooter
    • Use a tweezers or pen to loosen up the hole, and make it slightly deeper.
    • Position seed in the rooter plug, pointy end up
    • Cover the hole on the rapid rooter plug by tearing a small piece of the plug, and loosely covering the hole.
    • Place rapid rooter, with seed in it, inside humidity dome, under flourescent lights (I use T5’s).
    • Rooter plugs should be moistened with plain RO water periodically, but only moistened
    • Heat mat is not needed – and it can dry the rooter plug too fast. Humidity only needs to be around 50%. I just mist the humidity dome periodically.
    • No nutrients are needed with seedlings until the 3rd set of true leaves.
    • I transplant when roots are showing through the bottom and sides of rooter plugs

    I’ve had 100% success over the last year or so this way. There are lots of ways to do it successfully, this is just mine. X

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    My seed germination technique I really like Rapid Rooter plugs. I've been germinating seeds in them since I started growing, and now use them for cloning…