How to Germinate Seeds

Updated: May 24, 2018


Cannabis, like all life, is fragile at inception. Sow cannabis seeds ¼-½” deep, pointy-end up, in a starter cube or well-aerated soil. Seeds germinate best at room temperature, with moderate humidity and a 1:1 ratio of air to water in the grow medium. Optimize environmental conditions to ensure robust germination and vigorous growth. Stable conditions and attentiveness are key to nurturing young plants.


Seedlings will emerge after a few days and reach toward light. The seed casing opens like a clamshell hinged at the pointy tip. This reveals a tender white radicle—a small root tip that plunges downward while the seed casing is thrust up toward the light. Emergent seedlings unfurl to greet the sun and push away the seed casing. All of this happens in the course of a week using stored energy from inside the seed.


Don’t stress—sprouting marijuana seeds is easy! Take your time, smoke a joint, grab a beer and turn on your sound system. We recommend the Workingman’s Dead for this garden project. And remember—no root, no fruit!


Creating a Fertile Environment


Root Riot or Rapid Rooter cubes are a favorite for germination because they make it easy to keep the grow medium irrigated for success. Germinating seeds are very sensitive to excessively wet or dry conditions. Tender young plants will wither in arid conditions or become moldy in a swampy environment. Keep germinating seeds out of direct light until they have emerged from the grow medium.


Seeds germinate best in cozy conditions. The ideal germination space is consistently 72°-75°F, 45% humidity, away from direct light and excessive drafts. The top of the fridge in the kitchen is often a good enough spot. Just don’t forget about them!


Soak Cubes Before Use


Cubes should be soaked in a bucket of water for a few hours before use to ensure that they are evenly hydrated. If a pH meter is available, adjust all water to 6.0 with a horticultural grade acid or base.


Organize Cubes In A Starter Tray


Place cubes in a propagation tray such as the Mondi Mini-Greenhouse Propagation Dome; however, don’t use the humidity dome. It is meant for cloning and it will cause mold and moisture stress if used for seedlings. Make sure to label each seed in the tray!


Insert Seeds Into Cube


Plant seeds in the prefabricated hole in the cube, or flip it upside down and make your own hole. Insert the rounded end of the seed downward and insert to a depth of ¼-½”, approximately to where you can no longer see the seed. A pair of tweezers is useful for this step.


Water Cubes Daily


Water cubes once a day with plain water, or more often if the germination room is dry or drafty. Check on the cubes several times a day and be mindful of cube color. Wet cubes are dark brown; dry cubes are light tan. Do not fertilize yet.


First Emergence


Seedlings will usually emerge from the cube in 24-72 hours, sometimes longer. At that point, they should be transplanted and placed 12” under cool spectrum fluorescent lighting. Germinated seeds usually shed their seed casing as they first emerge from the cube; however, sometimes the seed casing will get stuck and appear to trap and prevent the emergence of the first set of leaves. The seedling will almost always shed the seed casing eventually, even if it takes a week. Attempting to remove the casing manually may physically damage the tender seedling.


Check out How To Take Care of Cannabis Seedlings for information on what to do next!