After seeds have germinated, it’s time to plant them into the pots. Plant the seeds just 3-5 millimeters below the surface of the earth, ideally with the tiny root facing downwards. This can help to avoid time-loss and seeds don’t have to figure out how gravity works.
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.
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.
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.
Aim for humidity levels of approximately 70%. Small propagators can be an option if you start in very small containers but autoflowering growers planting in final pots need to monitor, and eventually raise, the humidity inside the grow room.
There are basically two different techniques that are commonly used to germinate cannabis 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.
Are you concerned about the delicate seedling stage when growing cannabis? Don’t be! Follow these 3 steps and cultivate healthy seedlings.
If your final container size is up to 11l, you have the option to sow seeds directly. This is only a viable option when growing from seed. Clones will not take root in such a large container. Initially, seedlings in large pots will grow more slowly than those in smaller containers. After a few weeks of vegetative growth, the difference is negligible.
Roots grow in the dark. That’s why we advocate 18-6 or 20-4 over a nonstop 24-hour light cycle. High humidity, ideally around 70% RH, and temperatures in the 20–24°C range make for a perfect seedling habitat. A propagator, thermo-hygrometer, and a spray bottle of water are the tools to help you dial it in.
Before we go into the specifics, we need to be clear that starting in one medium and switching to another can be hazardous. Keep it simple and keep it consistent. You can’t start seedlings in soil and transplant later into a DWC bucket.
Don’t wait too long to transplant. Rootbound plants will take time to recover and may be permanently stunted. In general, it takes 7–10 days for a seedling to take root and outgrow small starter pots of 1l or less.
Rockwool cubes and blocks are made for hydroponic growers. Start your seedling in a small cube and it couldn’t be easier to transplant later. Simply cut a cube-sized chunk out of a larger block and insert. The process can be repeated with minimal stress to plants.
The medium must be wet, not waterlogged. An effective wet-dry cycle is the goal. Remember to resist the temptation to overwater. Better to mist plants with a sprayer if you are not sure. Touch the medium to feel how dry it is and keep RH high.
Next, make an impression in your large container with another small pot, or the one with the plant in it if you don’t have any others. Make this impression in the medium after you have watered it. This creates a perfect imprint for the transplant.
If you don’t transplant, then you eliminate the risk of transplant shock. But you also limit the potential of your cannabis plants. That being said, a first and final transplant is sometimes the best option for autoflowering strains with a short life cycle.
Cubes are the easiest to work with. Either cut a hole to size in a bigger block, or burrow a hole into the medium with your fingers and insert for a snug fit. Potting up takes a little more finesse. First, don’t fill your large container all the way to the top. Leave room so you can water properly later. If you pack the pot all the way to the top, water will mostly run off and not reach the roots.
Transplanting seedlings is a critical stage in the cannabis life cycle. Get your grow off to a great start with our guide to transplanting.