A challenge with tomatoes is keeping them watered while ensuring they develop strong roots, especially when you want to grow them in a pot because of limited space. Deep roots develop when there is deep watering. If you are in an area with drought and/or water restrictions you want to make every drop of water you give a plant count and not simply spill out the bottom of the pot.

I used pots like these last year from my cherry tomatoes, since I like to plant them in the same small area where I have my lettuce tubs and they worked very well:

roots went deep into the pots
the soil mix I used "kept" water in the pot
watering was easily done with a watering can with the sprinkle head taken off
watering every other or every third day sufficed during the hot, no rain spell we have in July
it was easy to feed the plant with compost tea or diluted liquid fertilizer during the growth and fruiting months

Step 1: Materials and Tools

Materials:

Pot 14 inches in diameter and 11 inches tall
Sturdy 2 quart plastic bottle with a cap at least 1 inch in diameter (for ease of filling)
1 cubic foot of container soil (you can mix your own)

Tools:

power drill
1/16 inch drill bit
short shovel for mixing soil and filling the pot (you can use a trowel, but it will take longer)
a container for mixing if making your own container soil

Step 2: Recipe for Your Own Container Soil

Ingredients:

11 quarts good quality garden loam
1 quart compost (tomatoes are heavy feeders)
7 quarts peat moss (coir may be used; measure after expanding it)
1 quart per-lite (to help keep soil "open" -- not compacting)

Mix all together.

This will serve to give your tomato plant a good start. You should be feeding it with a good compost tea or a diluted liquid fertilizer such as sea kelp at least once a month during its growth and fruiting.

Step 3: Prepare the Bottle

Strip off the plastic label from around the bottle.

Drill two holes in the front of the bottle within a half inch of the bottom.

Be sure to keep the cap. Using it (loosely) on the bottle reduces evaporation and keeps dirt and debris from landing in it.

Step 4: Set Up the Bottle in Planter

Add enough of the soil mix to the planter that the cap of the bottle will stand at or slightly above the pot rim.

Be sure the drilled holes face into the pot, and not to the pot side.

Step 5: Fill the Pot With Soil Mix

Fill the pot half-way up the bottle with the soil mix.

You will be adding:

1 teaspoon dolomitic lime (to offest the acidity of the peat moss and provide calcium)
1 teaspoon green sand (to supply trace elements)

Stir these into the soil (to feed the roots as they grow towards the water source.

Fill the pot to within a couple of inches of its top lips.

Again add and stir in:

1 teaspoon dolomitic lime
1 teaspoon green sand

Step 6: Set Your Tomato Pot in Your Planting Space

The newly filled pot is set in the corner of my greens garden with the water bottle easily accessible from its neighboring patio.

The cage is set up only for demonstration purposes. It will be removed when the tomato plant is transplanted from its seedling pot. Try to keep its root system as intact as possible. I usually push out a hole in the middle of pot and line it with compost before inserting the plant. I also try to place it deep enough that the new soil will cover an inch or more of its stem. Roots will grow from the stem area so covered and produce a sturdier plant. The first watering is from the top to settle the soil, but subsequent waterings will be via the water bottle.

After watering, screw the cap back on loosely so some air can get in to keep the side holes dripping into the soil; leaving the cap totally off will allow the water to flow into the soil, rather than slowly drip to maintain moisture.

Once the new plant is wide enough to span the bottom of the cage, place it over the plant.

Be sure to feed it with a compost tea or properly diluted liquid fertilizer in each subsequent month to ensure good growth!