If you have the time and money there are shops happy to sell you expensive seed propagators with heating pads and sun lamps. I can’t afford those, so I started experimenting with low budget, low effort, alternatives.
In order to germinate seeds need warmth, moisture, air, and in some cases light. So the logical way to store them is somewhere with the opposite conditions: cool, dry, airless and dark. I find wrapping them in a paper towel, zipping in a zipper-type plastic bag and refrigerating works pretty well. Also some seeds need a period of cold before they will germinate. This known as stratification and in the wild it stops them accidentally germinating before the winter hits. Storing in the fridge does this as well.
For larger seeds soaking overnight in a container of lukewarm water prior to planting is often helpful.
Plant the seeds in a good quality seed raising mix, usually about as far down as the seed is large. Then store in a warm humid place for about a week or two, depending on the type of seeds.
First I tried old egg cartons in plastic tote boxes.
They worked reasonably well provided I kept an eye on the amount of moisture in the box, but I found it very fiddly and messy separating the seedlings when it was time to plant.
Then I tried a self-watering propagator. I loved the fact that I didn’t have to keep checking the water levels. It was also much easier to get the seedlings out as it has a nifty tool to pop up all the plants so I can get my fingers around the seed mix. The drawbacks were that as a small gardener I didn’t always want to propagate 40 identical seeds. I tried using different seeds, but I ran into a problem when fast germinating plants were getting their roots into the capillary mat before the slower germinating plants had even germinated. And sometimes no matter how carefully I packed the cells sometimes the seed mix would crumble in my fingers as I lifted the seedling out. Finally I didn’t buy my propagators from the above link, but from a nearby large red shop. The plastic on mine did not seem very durable. The clear lids were the first to disintegrate, and the water trays seemed to twist and distort after one season.
Finally I tried using Jiffy pellets. These are sold in a dried and compressed form, and they need to soak up water before being used. The first kind I tried weighed 7 g when dry. After adding water they swelled up to about 57 g, looking rather like a teabag stuffed with peat moss. Because they store so much water they don’t need wet feet or constant watering. I used to over-water them and had quite poor results. Now I measure out 40 mL of warm water for each seven gram pellet and let them soak it up.
After that I put nine of them into an old two Litre ice-cream container before dropping in the seeds and pushing a little of the moss over them. Then I put the lid on the ice-cream container, label clearly, and place them in the back of my hot water cupboard for week. After that I have a peek every couple of days to see how they are getting on.
I have recently found a smaller version of the Jiffy Pellets. These are 36mmx7mm, weigh 5.6g dry and about 43g when saturated. I add 30g of water per pellet, and I put 16 in a 2L ice-cream container. I have also tried putting the 16 pellets into the ice-cream container dry, adding 500mL of water, putting on the lid, and warm in a microwave oven until all the water is absorbed. Its simpler, and has the bonus of making sure everything in the container is sterile. Just remember to allow everything to cool before adding the seeds!
Once the seeds have germinated store them in a well-lit place, such as a windowsill. I still avoid direct sunlight at this stage. Once the seedlings have their second pair of leaves they seem much hardier so then I transfer them to a planter bag. This is where I find the Jiffy pellets handy, because they make transplanting so easy. Just pick up the peat pellet and place it in a planter bag.
I used to use a collection of old plant pots that I had accumulated, but the planter bags just make everything easier. They are cheap, reusable, and easier to get the plant out of than a pot due to their flexibility. They are available in most garden centres, and the garden areas of the larger department stores. They are available in all sorts of sizes based on the old pint measurement (600ml). I like the 3/4 size planter bags, because four of them will fit nicely into an old ice-cream container. Then I take them outside or put them in my mini greenhouse.
Some plants don’t like the shock of moving from a propagator to the outdoors. They benefit from “hardening off”. The first few days I take them outside I don’t put them in direct sunlight, and then I bring them inside again for the night.
Once the plants are about 8cm tall they are ready to transfer to their final location. I usually sprinkle a few Quash snail pellets around them when I do. There are cheaper snail pellets out there, but they usually contain a nasty chemical called metaldehyde which is also poisonous to other animals including birds, hedgehogs, cats, dogs, and curious children. Quash is made from a bran/iron EDTA mix that is harmless to other animals. In fact Iron EDTA is used to fortify some foods.