With compact fluorescent lamps (usually 100w or more), a distance of around 15cm should be maintained between the top of the young seedlings and the bulb.
If using normal fluorescent tubes (18-36w), seedlings can be kept within a few centimetres of the light source.
If outdoor temperatures are suitable, seedlings may be acclimatised to direct sunlight by giving them progressively longer daily exposure to outdoor conditions.
When using HID lighting (usually a metal halide lamp), young seedlings should be kept at least 50cm from the bulb.
“When can cannabis seedlings be put under lights or in the sun?” is a common and sensible question that is often asked by novice cannabis enthusiasts after germinating seeds indoors under lights.
Cannabis seedlings growing under lights should always be given a gentle breeze from an oscillating fan (a small household fan on the lowest setting is fine), as constant gentle movement will strengthen their stems significantly.
Seedlings can be kept by a sunny window, until they’re ready to grow outside.
For those who are growing indoors, cannabis seedlings may be put under lights as soon as they emerge from the soil or growing medium.
If cannabis seedlings grow tall and then fall over, this is almost always a result of growing in an environment with static air.
When cannabis seedlings have grown their second or third set of serrated leaves they are usually hardy enough to flourish in direct sunlight. Learn when that is and how to do that now.
Simply drop your seeds into a glass of drinking water and wait 24-48 hours until seeds have cracked. Wait until you see the first few millimeters of the root, and make sure water temperatures are between 20-25 °C. Place your cup somewhere light doesn’t reach it.
Mastering the delicate seedling stage is crucial to grow strong and healthy cannabis plants. Read this blog for further information on how to cultivate cannabis from seed to seedling.
Before germinating our cannabis seeds, we make up our mind about containers and soil, assuming most rookies prefer soil due to simplicity. At this point, we already need to differentiate between autoflowering – and feminized/regular seeds.
It’s not necessary to use your powerful HPS or LED the first 10-14 days. CFL’s with a blue light spectrum (daylight/coolwhite) will get you very good results. Either built your own light fixture using T5/T8 sockets or buy 23-30W CFL’s with the standard European E27 lamp socket. Compare different bulbs and choose the ones with highest lumen output.
High quality organic soil that is “light” when it comes to pre-added nutrition works best.
Feminized- and regular cannabis varieties give growers the possibility do decide when the vegetation period ends, and the flowering period starts. This is why transplanting “feminized” seedlings is not such a big concern, in contrast to autoflowering strains. When a few days are lost due to stress recovery of the plant, growers simply increase the time-span of the vegetation period and compensates the loss of growth. Internet forums and grow reports can help to get you an idea what works best in terms of pot size(s) matching your setup.
Growers of autoflowering varieties will get best results when they plant the seed directly into the final pot, and need to pay very close attention to seedlings for the first three weeks. Mistakes in the vegetation period of autoflowering strains have fatal consequences, meaning low yields. Depending on the strain and growing method, pot sizes ranging from 5-15 liter can be used. The size of the pot will have an influence on the size of your plants, on yields, and on the frequency you water your plants. Tip: Airpots allow more oxygen to get to the root system and will boost vitality and final yields.
There are basically two different techniques that are commonly used to germinate cannabis seeds.
Carefully place your cannabis seeds between wet paper towels and place them in a sealable plastic container. Aim for high humidity levels inside the container, temperatures between 20-25 °C, and moist, but not overly wet paper towels. Check moisture and humidity levels regularly. Don’t completely close the container and allow some air exchange. This happens at a dark place.
Are you concerned about the delicate seedling stage when growing cannabis? Don’t be! Follow these 3 steps and cultivate healthy seedlings.