Nico’s Nuggets: Germination, Seedlings & Grow Medium

Hey Nico,
Loving your advice and videos! I am carefully planning my first grow and your experience is so appreciated! I have Rockwool ready as my germination medium and my seeds should arrive soon. I will plant in soilless mix following the seedling stage. Is it okay to plant seedlings started in Rockwool directly into my growing medium? No hydroponics for my first grow, as I am a good gardener in general, but no experience with hydro! Need advice geared towards that. – Many thanks, Kathy via

Greetings Kathy, and thanks for the support and kind words! Congrats on beginning your first grow. I can assure you it will be a rewarding experience in more than one way.

Of course, I agree that staying away from hydroponic systems, as a novice grower, is a smart idea. Hydro growing may help increase yield, but by no means does it ensure better quality. Not to mention there is a lot more that can go wrong with hydro growing than simple soil gardening.

Once you have germinated your seeds in Rockwool it will fine to transplant them into your soil-type medium. Because you are germinating your seeds in Rockwool plugs, be sure to keep a soft light on above them so that once the seed sprouts it will continue to grow upward toward the light. It is also important to understand that you will need to transplant the entire Rockwool plug into your soilless medium because the roots will have grown into the fabric, or wool, of the plug, making it impossible to remove with out extensive damage to the seedling. However, it is perfectly fine to plant the Rockwool plug in the soilless medium you have chosen. Some growers do not like to mix substrates and if this is the case, you can always simply switch from Rockwool plugs to peat plugs, which are also a soilless solution and will homogenize well with whatever soilless agent you are using. Remember to bury the entire ply just below the soilless medium’s surface as sometimes Rockwool plugs can stick out and become moldy from the extensive watering that will soon ensue.

Seeds germinated in Rockwool plugs begin to show roots after 7 days.

Transplanting cannabis plants of any age can be a stressful activity for the plant. One must take great care in this exercise, particularly around the root zone. When plants become stressed, their development and growth can slow and affect maturation times as well as yield or potency. As such, growers want to transplant as little as possible. When growing from cuttings, many growers put their clone plants directly into its final container as soon as roots appear on their cuttings. The same can be done with young seedlings started in plugs. The key is to make sure your containers are big enough to take your plants to full term. Some growers prefer to transplant seedlings twice – once after germination and then again a few weeks later towards the end of the vegetative cycle, just before inducing flowering. The choice is up to you and may depend on factors such as space, budget and timing. A standard timeframe from germination to seedling is about two weeks, with the following vegetative phase running anywhere from two to four weeks. Then flower time will run minimum eight weeks, depending on the genetics being grown. All in all, 12 weeks is a good average timeframe from start to finish with which growers can plan their grow cycles. And in the end, the reward is always worth the time!

Thanks for reading everyone and remember: Grow… And help the world grow, too!

Got questions? Email ‘em over to Nico at and be sure to put “Nico’s Nuggets” in the subject line!

Follow Nico on Social Media: @Nico_Escondido (Twitter) & @Nico_High_Times (Instagram)
Top photo: Transplanting into soilless mediums once seedlings are well-rooted. 

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