Germination is the first stage of turning a seed into a plant. Seeds germinate naturally in nature, and provides for the furtherance of the plant population.
Our aim when we sow seeds is for them to ‘germinate’ and thereafter turn into young plants.
Assuming we give the seeds the correct conditions for growth, the first visible change in the germination process, is that the seed case ruptures or splits, allowing the primary root (the ‘Radical’) to emerge - pushing down into the soil to anchor the seed into the ground or compost.
The next visible stage, and normally the first we notice above ground – is the emergence of two seed leaves – sometimes pushing the seed coat upwards out of the soil when they do. At this point, we can safely say that the seed has germinated – the young plant has been born!
Most people will be aware that seeds are generally two halves. (There are other seeds which are whole) This is particularly noticeable with members of the pea family, or even nuts. The two halves of the seed are covered by the outer coat or shell of the seed. The two halves of the seed are actually the first pair of leaves that we see upon. They have softened with the moisture and warmth we provided, and then transformed into the fist seed leaves.
They are not true leaves – simply the food supply to enable the plant to start to grow properly. These two leaves are called ‘cotyledons’. When they were inside the seed pod, they were the primary source of energy (food) which allowed the growth to take place this far. The root at this stage is basically an anchorage system, being supplied with food resources from the cotyledons. Most seeds conform to this description, and are called di-cotyledons; there also 'mono' cotyledons.
After a while, the root branches or at least starts to perform its other main activity of supplying water to the plant, which in turn contains various nutrients to take the plant further along the growth stage. In tandem with this new root activity, the ‘true plant starts to emerge from within the bud situated in the apex of the cotyledons. If all goes well, a short stem with ‘proper’ or true plant leaves will emerge.
Image shows the germinated seedling, with the two large cotyledons and in the centre, the bud that will emerge as a stem having 'true' leaves.
These proper leaves will quickly start to fulfill their proper function of transforming the raw ingredients from the soil nutrients into available food/chemical which the plant needs in order to thrive – or at least survive. At this point, the cotyledons will have done their job of providing the initial food reserves, and simply wither. They are no longer required.
If the bud within the folds of the cotyledon is damaged or destroyed, then eventually the cotyledons will die – for they are unable to fulfill the role of proper leaves. They were simply there in the form of the two seed halves, which was home to the plant bud. Cotyledons do not continue growing after they have done their work.
In successful germination of our plants, we should end up with a basic root system to support and absorb nutrients from the soil, together with a main stem which now has at least a pair or more of real leaves. At this point, we can safely say that our seeds have germinated. We now have a very young plant – a seedling – which we have to help grow into the plant which will give us the flowers or food that we require.
Congratulations! You have successfully germinated the seeds, and are the relieved if not proud owner of several seedling plants.