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germinating cannabis seeds in humidity dome

Step 3

Heating mats should be avoided unless you need it in the wintertime. A dysfunctional heating mat, or a mistake in the temperature control, can easily boil the seeds or dry up the substrate and shrivel the freshly emerging seedling. Your pots/rockwool cubes should be placed in a space with ambient room temperature (ie. 24-26°C/75-78°F). In the winter use a small electric or gas heater to warm up your grow space. You can also switch on the HPS lamp and put the pots at a close distance underneath.

Many growers make the mistake of thinking that they need a high ambient humidity for germination or seedlings. This is an unfortunate myth of cannabis cultivation. The high humidity and lack of fresh ventilation quickly causes fungus in the soil or growing medium and the seeds can rot!

Please use high quality soil that is suitable for seedlings (see our SOIL GUIDE for more info), or use rockwool starter cubes for germinating seeds.

You can use a humidity dome/mini-greenhouse as a tray for germination but you must keep the lid half-way open or completely seperate to ensure fresh air exchange and humidity levels at or below 50%.

It is in a growers best interest to choose a germination method with the lowest risk of complications. Because we want customers to have the highest success rate possible we recommend the most convenient and safest method. This does not mean it is the only option. We simply believe it carries the lowest risk for germinating fresh seeds. Planting seeds directly in the substrate is also the most plant friendly method for any type of seed stock. The reasons are explained below in paragraph 2 & 3.

This robust & portable 1m x 50cm Mini Garden combines the benefits of a raised bed propagator and cold frame into one to allow convenient growing from seed in an outdoor space. The large inside area and numerous vents enable easier control of humidity levels and temperature. The bottom tray can be raised up or down. There is enough height to accomodate seedlings and young plants.

Immerse the rockwool cubes in lukewarm water with a pH of 5.6-5.8 until the rockwool is evenly wet. Overnight soaking is not required for starter cubes. Let the water drip off. squeeze lightly to assist. Place the seed in a horizontal position into the hole (this is the easiest method). The taproot can grow downwards assisted by gravity. Alternatively, you can also place the seed into the hole vertically with the rounded end facing up (cannabis seeds sprout by opening the shell at the pointy end where the taproot grows out). Cover the hole with a small piece of rockwool. Choose a fluffy piece of rockwool. you don't want to tightly plug the hole because the seedling has to grow out with ease. Water the rockwool cubes with a weak nutrient solution of 10-15% of the recommended dosage (or EC 0,6) and pH 5.6-5.8. You can also germinate using pure water. Put the rockwool cubes at a warm location. Temperatures at 25°C/75°F or higher accelerate germination. Take care that the rockwool cubes do not dry out or stand in the cold (i.e. at or under 21°C/70°F). They should also not sit in water. Usually the cubes require to be moistened with pH adjusted water every 1-2 days. Use chlorine free water such as mineral water. Within 3-5 days the seedlings should appear out of the cubes.
Hot tip: to prevent the cubes from sitting in water put some perlite at the bottom of the tray for drainage.
You can switch on your lamps during germination to provide warmth or when the first seedlings appear. Since they might also grow out of the cubes during the night it's best to have lighting switched on 24 hrs.

Theres no argument here, just the right way of doing somthing versus all the bs that gets perpetuated by half arsed growers.

But. on the humidity dome, I use one and have every time and it works for me. I never had any issues with mold or fungus or anything else. I think the mold and fungus part comes from how wet your soil really is. Mine is damp, not soaked. All of my seeds have popped without issues doing it with the dome, as a matter of fact, just popped 4 and they came up in 4 days. I do take the dome off occasionally during the day, maybe once or twice at most for 10 minutes or so, but then it is back on until I see stable seedlings.

Well. to quote each his own. ..sorry could not resist, its on your member profile.


The dome is for keeping the seed from drying out. You want warm, moist, not saturated, and not dried out.

Ive heard different opinions regarding this, this is my first time using a heat mat and humidity dome, some say dont use a humidity dome when germinating because it could cause mold to grow on the seed.

Keep things clean.

Ive always just used the paper towel and glass mug method and then transferred to a make shift humidity dome after leaves. Ive also seen some say dont use a humidity dome at all for any stage although personally Ive had better luck with a humidity dome then without, whats your take on the dome for germination?