It's important to understand Seeds if you are interested in Seed Germination. When you examine a seed the first thing you see is it's Seed Coat. The Seed Coat provides protection against temperature fluctuation, parasite penetration and physical damage.
Within The Seed Coat is the embryo. The embryo has all the parts of a full grown plant, with leaves (known as cotyledons), and a root. To provide the embryo with food the seed if filled with endosperm which is made up from Starch, Oil, and Protein.
Seed Germination is a fascinating process, during which you can see a small shoot emerge from the small seed.
The first indication of Germination is the absorption of lots of water, which activates an enzyme to increase respiration and the duplication of plant cells. When the embryo gets to large for it's Seed Coat, the coat busts and you will be able to see the tip of the plants root. The Plants Root is the first part of the plant to emerge, and this is to secure the seed in place and to allow the absorption of water and food through the surrounding soil.
Here are some useful things to remember:
Seeds need water to initiate germination, so presoaking seeds can speed up the process.
A root needs water when it emerges, so if you plant seeds in the middle of summer plant them deeper in the soil to avoid the dry ground.
Bigger Seeds will generally have more endosperm, so will be ably to feed the plant longer, so it's possible to plant larger seeds deeper in the ground.
Planting left over seeds
We don't always use up complete packets of seeds in a single year, so you can save yourself money be using left over seed. The best time to get out your seed packets to test seed viability is as Winter is coming to a close.
Remember that there is no guarantee that seed you have left is good seed, age and how long they have been stored can affect how viable to seeds are and how likely they are to sprout.
There is a simple test you can perform to see how viable a batch of left over seed is:
Take exactly 10 seeds and place them on top of a damp folded paper towel.
Place the paper towel and seeds into a plastic sandwich bag and seal it tight.
Make sure you label the bag with the date and type of seed being tested.
Leave the bag at room temperature for a week and count the number of seeds that are sprouting.
If you have 8 or more sprouting seeds then you have a good batch which can be planted, if you have 6 or 7 sprouting seeds then you can still plant the seeds but sow them more thickly.
If you have 5 or less sprouting seeds then throw the seeds out.