There are many ways of growing tomatoes, and I will list a few ways here.
SOIL is the easiest and safest way to start growing tomatoes. There are plenty of natural nutrients in the soil and watering is not so critical. Saying that, certain guidelines should be followed. To start with, a good helping of well-rotted manure should be forked in before planting. A liquid feed will still be required at least once a week during the heavy cropping season, but it is a really fool proof way to start. Do not think that there will be enough nutrients in the soil to give you a good season's cropping. Your plants in the greenhouse can grow to at least 15ft, if given enough space and looked after properly. You do have more of an investment with a greenhouse, so you do need to have more production per square foot.
Eventually, you will need to rest your soil, and eradicate pest and diseases, and unless you can sterilise your soil effectively, there is no other alternative, so I have listed a few ideas below.
PEAT TROUGHS or greenhouse raised beds are a perfect solution for poor soil, after many years of growing in it. You still have a good depth of soil, so watering is not a problem like it is with peat bags.
The peat/soil mix can be changed every few years to keep disease and pests away. You can plant your tomatoes into a large pot then place on the bed. For me, this is one of the best systems for greenhouses and once I have used my soil for a few years, it is the system I will be using to rest my soil.
You do not even have to use wood, just put some small posts in either side and run a string down. Then use some wide thick plastic to make your trough, folding the sides into the inside of the trough. I will try to make one up and show a picture some time in the future. But this is one I found on the web which gives a good idea.
PEAT BAGS are often used when you have poor or diseased soil, or on patios etc. They have some slow release fertilisers already in them, but this will only last a few weeks of feeding and will get washed out, so you do really need to feed at every watering, or at least a few times a week to get a good yield.
It is imperative that the peat does not dry out, and commercial growers use a trickle irrigation system several times a day to ensure even watering. Watering too heavily with a hose will leach out the fertilisers, and also could cause root rot. Also be sure to put three small slits about an inch off the floor to allow your bags to drain, make sure the peat is well soaked before you do this, then keep it permanently moist.
Peat bags will give you fantastic crops, but do not go away on holiday for a week and expect to come back to find your plants still healthy, in the middle of summer.
However, you could plant your tomatoes into a large pot, then place it on the peat bag, as this will give you a better reserve, but make sure there are adequate holes in the bottom of the pot to let the roots grow through to the peat bag. The ones shown here are specially made for the purpose, with small water reservoir, so drip irrigation would not be needed, as the water will soak through slowly.
Hobby farmers and home gardeners have used hydroponics on a smaller scale to grow fresh vegetables year-round and to grow plants in smaller spaces, such as the basement or an apartment or balcony. Many greenhouses and nurseries also practise hydroponic techniques by growing their plants in a soilless peat or bark-based growing mix and supplying nutrients through the water supply.
Soilless gardening offers many advantages to the home gardener or part-time farmer. Since a sterile medium is used in hydroponic systems, there are no weeds to remove, and soil-borne pests and diseases are minimised, if not eliminated completely. Properly grown and adequately nourished hydroponic plants are normally healthier and more vigorous because all of the necessary growth elements and nutrients are made readily available during growth.
Hydroponic plants grow and mature faster, yielding an earlier harvest of vegetable, herbal and flower crops. Hydroponic gardens use less space since the plant roots do not have to spread out in search of food and water. This small space requirement makes hydroponics ideal for limited space home gardeners, small scale and commercial farmers also benefit from better and more productive use of greenhouse space.
The big advantage to hydroponics is the ability to automate the entire system with timers and remote monitoring equipment. Automation reduces the time it takes to maintain plant growth requirements and the growing environment. Automation also provides flexibility to the grower (owner) as one can be gone for longer periods of time without having to worry about watering the plants.
Hydroponic techniques also allow for precise water and nutrient application directly to the roots of each plant saving on costs. Water is reused in these systems and less is lost through evaporation or via field run-off.
However, get the watering wrong, and you could lose your crop over night.
I have been involved in growing tomatoes with this system, but it was a commercial nursery, with high tec monitoring equipment.
There are some small scale systems for sale, but I do prefer the flavour of my soil grown tomatoes. Here is a simple garden system.