Harlequin germinates then stops growing

From a fellow grower: No idea what is going on. All 8 seeds had a great taproot. Once planted none of them germinated. I have a grow station and even have tried a couple different seedling soils. I still haven’t had any success. The temp is about 77-80 plenty of humidity and enough water. I understand they may be temperamental or moderately difficult to grow but I am not a newbie and I germinate as described in your germination guide. Maybe this strain needs something extra?

  • Strain: Harelquin
  • Type (fem/auto/reg): Photoperiod
  • Climate (indoor/outdoor): Indoor
  • Medium (soil/hydro/details): Soil
  • pH of runoff or solution in reservoir: N/A
  • Nutrient mix strength (EC/TDS)
  • Light type & schedule: Grow light on at 8am off at 5pm with seedling heat pad
  • Temperatures day & night: Day temp average is 78.9. Night time temp average 71.2
  • Humidity day & night: Relative humidity day 41.2 Night 40.5

This is like a very uneducated guess of mine.

PH and/or overwatering.

If you have sprouted many Marihuana seeds with this method and this is the first time failing, there is something off. What it is I’m not experienced enough to tell.

Water schedule and PH reading would help to eliminate confirm the most common reason for sprouting issues.

There are several things that could be killing the sprouts.
#1 is overwatering. Soil should be slightly damp, too much water and you run the risk of fungus rotting the seed.
#2 I have seen the heating pads cook the seeds in certain situations. The pad is supposed to add 10 degrees to whatever the temp already is, but sometimes it goes higher. If you are running 70 to 80 without the mat then just try without the extra heat. My tent runs 66 at night and 80 during the day and my seeds sprout in two days after a 24hr soak. My soil is just damp, and I don’t water for at least a week after they come up. I keep a clear dome cover on them for the first two days.

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I agree, something must be off. I guess I am mystified. Testing is all good, soil is damp but not wet. I am going to run a couple of soil tests on both of the seedling soils I have but I can’t imagine that to be the problem.

Well the water should be fine. The soil is damp but not wet. I typically spray with water every few days as necessary. I was thinking the temp as well. It was running a little cold at first, so I chalked up the first couple of “seed deaths” to cold. I adjusted the heat and it now is running 70ish at night to 78 during the day. Even bought a blue tooth gauge so I can monitor the temp/relative humidity from my phone. Handy little device as it also gives me averages over time and any large variances if they occur. Both have been very stable. I am going to test the soils to make sure the ph is ok.

Couple of things. No idea if either would stop them from germ’n. But feel they need to be said anyway. Firstly welcome to ILGM!

Ok humidity. Seedlings love humidity. If they never sproutd, then its a moot point. But 40s is more flowering levels. At the newborn stage, i like to keep it as close to 100 as possible. Wet domes, spritzing, whatever i can do to keep it moist and warm.

Second thing is light hours. No idea why, but i put my seeds into soil and under 24-0. Just seems like they’d want to come out and see the light as early as possible.

But onto ur germing problems… too wet dirt (mentiond above) will drown out seeds. N ur soil looks great. Maybe u could talk us thru your germination process?


Hmmmm, maybe I can try the 24-0 lighting…couldn’t hurt at this moment.
For my planting I usually soak 2 seeds at a time for about 24 hours or until I get a pretty strong tap root. All of these seeds have tapped quite well. While the little guys are developing their tap root I mix my seedling soil with some water to moisten it and place it on my heat pad so my tapped seeds will be placed in the same temperature of soil when they are ready.
When I have a good tap root I take my moistened warmed soil and drop my little guy in and cover it loosely with soil.
They have a moisture cover and as I said earlier they have about 8 hours light with a heat pad on 24 hours.
That is about it. Usually, it works like a charm and I had some excellent grow for the last couple of years. This is a new strain for me though.

Are we sure it isn’t the 9hr of light window? Why not 2 CFLs from the grocery store for 18 hrs? Just a guess

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Add a little myco, even if it’s the cheapest kind. Try to mist versus watering.

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All of that sounds spot on… hmm im at a lose myself

Those mycos wont hurt a bit!

I do mist and not water so that is good. What is myco and where would I get it? I am not familiar with it at all

Mycos is short hand for mycorrhizae bacteria. They come in a litany of products. Mykos, Recharge, Tribus among a few others.

They are beneficial bacteria that aid in root growth and the uptake of nutrients. Not the cheapest supplement by a long shot but gamechanging. A healthy microbe herd has basically eliminated the need for pH’n in my grows. And helps ensure a healthy rootball

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Thanks for that! I will find some for sure and add it to my grow necessities!

You have a nice existing starting heard …but you will periodically need to re inoculate the soil ( recharge, microbe life foliar spray and root dip has hasent concentration mycrozae fungi and bascilius bacteria… I use it with all food and soil

Ok, this is amazing! I actually HAVE Mykos WP. I went to our local grow store party in the fall. They had all kinds of samples of different stuff and I have two packages of the Mykos. I am definitely going to add it to my planting. Going to try 24 hour lighting. Now we wait😀


Wow, thanks all! Finally, I have a seedling😀! Did the 24 hour lighting as well as added Mykos to the soil. It was up in a little over a day. Hopefully, this will be a consistent fix for my plants. You guys rock!