I thought it would be good to do a step-by-step description of the process here, with photos.
Now I tend to be quite methodical about my gardening and have been known to spend more than is strictly necessary on getting the 'right' gear, so do bear in mind that you can do this more simply and for virtually no outlay except a bit of potting mix …
Assemble the stuff you need. At a minimum: seeds, potting mix, pots, water, a container with a transparent lid to act as a controlled environment. That can be as simple as half a plastic bottle to put over your pot.
I use Jiffy coir peat pots because you just plant them out, pot and all. The seedling roots grow through the pot and there is little or no transplant shock (IF you wait until the garden soil is warm enough; see below).
I also use a few extras: a potting sieve, a propagation thermometer, plant labels, a propagator with a vented lid, a heated propagating tray with a thermostat.
Soak your Jiffy pots. You must get them completely wet at the outset.
Arrange your wet pots in your tray with no gaps. The square pots are much better for this than the round ones.
Fill your pots to the rim with your growing medium. I use a general organic potting mix, as seed raising mix doesn't have enough nutrients to keep the seedlings going for the two months they'll be in pots. Then give the pots a good water; the growing medium will compact slightly, giving you a few millimetres of space to sow and cover your seeds.
If you're as forgetful as me, write your plant labels NOW and arrange them in the same order as you're going to sow the seeds in the pots. All the solanaceae (tomatoes, eggplants etc) seeds look very similar.
Sow your seeds. I usually sow three per pot. Two of them will be culled later.
Cover your seeds with a fine layer of potting mix. I use a sieve for this - seeds won't grow too well if they're weighed down by a big lump of potting mix or bark! Water in gently. I find these little watering can tops for plastic bottles very handy for watering seedlings.
Get your plant labels in before you forget what you sowed where. (You may begin to see a pattern emerging here. Yes, I really am that absent-minded.) You'll notice there's also a thermometer in one pot. More about that below.
Set up your heated propagator tray if you have one. It wants to be somewhere out of the sun and the rain - this unit is weather-resistant, but not water-tight. Also, your seedlings may dry out or get too hot in direct sunlight. When they get their first true leaves, you can start to put them out in the sun. But I'm getting ahead of myself …
This propagator tray has a felt blanket which must be kept moist, otherwise it will not transmit the heat effectively to the pots.
Put your lids on your propagators and close the vents. Put the propagators on the tray and turn it on. You want a soil temperature of about 20C. To achieve that, you'll probably have to turn the thermostat up to about 28C. That's why there's a thermometer in one of the pots: the temperature of the heating unit will be higher than the temperature of the soil, and it's the latter that counts. You can use the thermometer to monitor the soil temperature and adjust the thermostat accordingly.
Sit back and wait … and wait …
It can take about 2 weeks for tomatoes to emerge, and the warmth-loving eggplants and capsicums may take up to 4 weeks. In the meantime, the pots shouldn't need watering - unless you let the sun get to them. You will however need to wet the felt blanket every couple of days, more often in hot, dry weather.
Your seedlings will first put out a pair of cotyledons ('baby leaves'), then a week or two later their first true leaves. At this stage, cull two of the seedlings in each pot, leaving only the sturdiest one. Your pots will need watering regularly now and you can give them a very diluted seaweed solution and/or worm juice. Just a few drops of the concentrated stuff in their watering bottle is sufficient. Make sure they get plenty of sunlight now, but not baking heat. If you have a sheltered spot (such as a cold frame with the lid off), you can take the plastic lid off of the propagator during the day. You don't want too much humidity now or your seedlings could damp off and die.
When the soil temperature in the garden bed is around 18C, it's time to plant out your seedlings. On the Bellarine Peninsula, this will probably be around the second week of November. You can warm up the soil by stripping off any mulch for a couple of weeks beforehand.
Transplanting tomatoes, eggplants and capsicums into cool soil is a waste of time and plants. Your plants will be set back, more vulnerable to pests and diseases, possibly permanently stunted, and you won't get fruit any earlier, so unless you have a hothouse, be patient.
It's all to easy to get 'garden centre-itis' and bring home luxuriant tomato seedlings in mid-September. The poor little buggers will turn up their toes when you stick them in your 10C soil. You have been warned …