Sowing tomatoes
Tomatoes are not hard to grow. If you've every grown them outdoors, or made your own compost and spread it over your vegetable garden, it's likely you've had unplanned tomato plants springing up in the past. That said there is a broad spectrum of health for tomato plants, and getting the best possible crop requires reaonably careful management and growing - you can't just sow the seeds and forget about them until harvest.
To get the best from tomatoes they need to be started inside, then transplaneted once or twice until they are large enough to take up their final position, be that in a pot, growbag, basket or bed.
We sow into standard sized but extra deep seed trays, filled with John Innes No. 1 compost. Fill the tray almost to the top with compost, then make 24 evenly-spaced dimples in the surface with your index finger. Place a seed into each dimple, and optionally cover with a fine layer of compost. If you're sowing more than one variety to a tray label them clearly and securely - we've had several seasons where the labels went missing and we didn't know which variety was which until late in the year!
Water well and place in your greenhouse or on a sunny windowsill. If your greenhouse is unheated cover the tray with a sheet of agricultural fleece. The seeds don't need to be sown deeper than a quarter of an inch, and will germinate quite happily on the surface - remember they need moisture, air and warmth to germinate.
We sow our tomatoes in early March, and place them on a heated pad in an otherwise unheated greenhouse. Germination rates are nearly 100%, and given that some varieties come in packets of only 12 seeds it's wise to take good care of them. You can sow successionally, but given the climate in the UK it's not often possible to get more than 2 crops in a year. If you live in the south of England try sowing some seeds before Christmas, then a second sowing around the end of February - you should be harvesting fresh fruit from late June to October.
Within 7-10 days the seeds should germinate and you'll see the first shoots of life appearing. Keep the compost moist, protect from frost, and when the seedlings have formed 2 leaves move on to the next step, potting on.