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starting marijuana seeds under led lights

As soon as your seeds have sprouted, your soon-to-be cannabis plant will need light to grow. Compared to more mature plants, however, your seedling is much more sensitive to intense light. Because of that, you should be careful when starting out with strong LEDs.

These standard LED light fixtures were the first type available for growing, and today, they’re still widely available. These lights contain a lot, sometimes hundreds, of small to medium wattage LEDs (3–5 watts per single LED) in a compact fixture. Cannabis growers sometimes refer to these as “purple” lights, as they often comprise a mix of red and blue LEDs that combine to emit a purple hue.

If your LED has a dimming option, turn your light to a lower intensity. If this isn’t an option, consider moving your lights further up, away from the seedling. On the other hand, ensure that you do not move the lights too far up, as this could cause the seedling to grow spindly and lanky.


With less heat produced by lights, the soil in your pots will stay moist for longer, thus reducing the amount of times you need to water. If you’ve just switched from HID to LED and are used to your plants drinking quite a lot, you now need to be careful with your new watering schedule under LED, otherwise you might overwater your ladies.

As your seedling grows taller, stronger, and approaches the most robust part of the vegetative growing stage, you can then gradually increase the light intensity.

Before you go buying an LED grow light, it helps to know what’s available. Currently, there are three main types of LEDs that you can use to grow cannabis, each of which has its pros and cons. The type of LED light you should choose will depend on what exactly you’re looking for, and how much money you’re willing to spend.

Monitor your plant’s development; if all goes well, it should grow healthy, strong, and bushy. If it grows lanky and spindly instead, this is likely because your plant is not getting enough light. Increase the intensity by lowering the light toward the plant canopy or turning up the intensity using the dimmer if your light has one.

I hope you continue to enjoy the blog.

Seedlings intended for outdoor growing should be kept by a sunny window for the first week or two after emerging from the soil.

Good afternoon Jon,


If using normal fluorescent tubes (18-36w), seedlings can be kept within a few centimetres of the light source.

no light needed until they grow above the dirt

When they have grown their second or third set of serrated leaves (after the the round cotyledons that initially emerge from the seed) seedlings are usually hardy enough to flourish in direct sunlight.

First time grower here. I didnt germinate I just put them in soil. Do I need to put light on them or just grow till till I can see them a little and then put light??

Cannabis seeds only need three ingredients to be able to grow: heat, water, and air. Anything that provides those will result in a sprout, as long as the seeds are viable, so some precautions should be taken when storing seeds in warm or humid climates.

Soak the pellets in warm water and then poke a small hole into them, about a half-inch deep and just big enough for the seed to fit snugly into. Here, they can be watered, kept warm, and even begin to take root. The whole pellet will eventually be transferred to wherever the germinated plant will be grown.

Common Methods

They may end up soaking up more moisture than expected, so be sure to check on them throughout the process and add more water if needed. Not too much though, just enough to keep the paper towels damp.

When older, dried out seeds need to be revitalized, a good soak can wake them up when done properly.

Setups involving many pellets on a warming rack are colloquially known as “germination stations” and are very commonly used in both amateur and professional grows. Very little trauma to the seed can occur here, and the trauma of transplantation becomes a non-issue.