Jiffy's, peat pellets, and other types of starter plugs with an alkaline pH inhibit germination in cannabis seeds. Some substrates such as coco coir may also be pre-fertilized and have a high EC (salt) level Untreated coco coir contains toxic levels of sodium and chloride. Or they could have been treated with fungicides and pesticides. If you have used a particular product with poor results you should stop using it and switch to rockwool or soil.
c) This can happen for the same reasons as in b). But there can also be other factors involved. If a heating mat was used the substrate may have been heated up too much. In rockwool a high EC can kill the emerging seedling. Check the EC of your substrate and make sure your EC meter is functioning correctly. A sudden dry spell in the substrate is also lethal at this stage.
Seedlings cannot open their first set of leaves
The major cause is lack of light. The seedlings are stretching in search of light. This leads to elongated and weak growth. Give your seedlings as much light as possible. Move them closer to the lamp. Put them under an HPS lamp if available. If you are growing near a window move the plants to the sunniest spot or supplement grow time with a lamp. Outdoors you should also provide as much light as possible. Support the seedlings with a stick or looped wire while they regain strength. As soon as they have sufficient light they will grow vigorously.
b) Dark seeds indicate fungal attack. A whitish substance is visible fungal mycelia. Fungus spreads under cold, wet, & anaerobic conditions. Several combinations of factors can lead to seeds rotting: poor soil quality (infected, bad pH, or high EC), pre-soaking seeds in water, substrate is too wet, substrate is in a cold environment, and/or excessive high humidity caused fungal growth in substrate (due to humidity dome/propagator, pots covered with plastic, poor ventilation).
In some rare cases frost during delivery can damage seeds. If your seeds are subjected to freezing temperatures (such as lying outside in a mail box) you should dethaw them slowly. Put them in the refrigerator a couple of hours for this purpose.
This does not mean that pre-soaking should never be used with seeds from other sources, or that we criticize growers who prefer this method. We are aware that some breeders recommend it for their products. But to prevent complications and achieve the consistent level of high germination rates that you should be getting from your Mandala seeds please trust our advice and follow our guidelines.
Sometimes, you can end up with ‘bad’ cannabis seeds that will cause problems later down the line. In some cases, these seeds just won’t germinate. Although this won’t ruin your entire crop, it is a waste of time and money, which can be frustrating.
Sometimes, you can tell if a seed is good or bad just by looking at it. Here’s how to spot a healthy seed:
What Makes a Cannabis Seed ‘Bad’?
Cultivating marijuana is a bit of a learning curve, so don’t worry if you mess up your crop from time to time. It will only get easier with time.
One way around this is to purchase feminized marijuana seeds. In theory, all seeds in a feminized bunch will be female – unless you buy from a disreputable grower. Unfortunately, there’s no way to tell whether a plant is male or female simply based on the seeds.
At this point, you can transplant the seed into its pot. Use a pair of tweezers and handle each seed carefully, being careful not to touch the taproot. The taproot is fragile and may break if you’re not delicate; furthermore, touching it with your hands may contaminate it.
Putting the cannabis seeds in a glass of water and waiting 24 to 48 hours for their germination can be a fatal error for them. Re-hydrating the seeds in water is a good idea as long as they are not out of contact with the air for long, as they will be deprived of oxygen and most of the time they will end up dying; so if we use this method, we only leave them to re-to hydrate in water for a few minutes, although, preferably we will avoid any previous soaking or re-hydration (which in any case is not necessary).
Every grower, almost without exception, will have occasionally suffered the death of a plant during cultivation, just when it seemed that everything was going along nicely. In this article, we’ll focus on the main reasons why seeds may not germinate properly, or why seedlings may end up dead in the first weeks of life.
What to do with leftover seeds or unopened seed packs
If we want to keep a seed package that’s still sealed, simply put the whole unopened pack into the fridge. The best place for its conservation is usually the small shelf where the eggs or butter are kept, although really any part of the fridge is ideal for storage.
Just as excess water is one of the most common causes of germination problems, the lack of moisture is equally detrimental to the process.
If the plan is to grow automatic varieties, then during the first two weeks we water with 100 to 350ml per irrigation, every 1 or 2 days. Remember that the substrate must maintain a minimum of humidity to allow the plant to feed and continue to develop normally. If it is raining and the plants are outdoors, it’s a good idea to move or cover them, to prevent the substrate from getting soaked, which could easily lead to root zone problems.