There are 2 choices to make when deciding on where and how you are going to plant your tomatoes with respect to soil preparation.
- Planting directly in the soil
- Planting in a pre-prepared container
Planting Tomatoes Directly in the Soil
For the best results consider preparing the soil by digging a trench about 18″ deep and long enough to accommodate your tomato plants. The plants will normally require to be spaced about 18″ apart.
To help with water retention you can place a thin layer of a suitable mulch in the bottom of the trench, something like a layer of newspaper would be a suitable choice. Then fill the trench with a mixture of nitrogen rich compost and top soil.
The all purpose compost should be well rotted and matured to ensure an adequate supply of nitrogen to the plants. It is also a good idea to warm the soil slightly for tomato growing, this can be achieved by placing a dark layer over the ground that absorbs the heat from the sun and transfers it into the ground. Once the soil has warmed a little the plants can be put in; typically in the UK this would be no later than the end of May, assuming that by this time there is no further risk of frost.
Once the plants are in, many people like to add a further layer of mulch over the top of the soil. There are advantages for doing this, but also disadvantages. The advantages are, that depending on the mulch selected, not only will the mulch prevent proliferation of weeds but can also supplement the plant feed if a nitrogen rich mulch is selected.
A disadvantage is that certain mulch types can keep the soil from being warmed, so look for a suitable compromise. You can visit Tomato Mulches for more detailed information.
Planting Tomatoes in Containers
The term containers has been used loosely here, because it refers to both pots and growbags. If you use a plant pot then ideally it will be around 12″ in diameter. Growbags tend to come in 35 or 40 liter sizes and the recommendation is that you would put 2 to 3 plants per growbag ideally.Visit Tomato Containers for a range of options.
Before using a plant pot you should clean the inside with a dilute solution of disinfectant, Jeyes fluid would be a good choice. Then fill the pots with a good quality, well matured, nitrogen rich compost to about an inch from the rim of the pot.
Once the plant is established, you may find that you need to top up the compost a little as time goes on. The main source of contaminants to a tomato plant is from the soil it is planted in, particularly after several seasons. That is why using containers is a good option and also why digging a trench and then renewing the soil in a trench can save you quite a lot of grief. You could probably get by with renewing the trench perhaps every 2 or 3 seasons, unless of course you have already experienced any problems.