I have been doing container gardening for a few years. I use the 12 gallon containers from HD. About $8 each. Drill the weep holes 2 inches off the bottom so the plants have a reservoir of water to feed on as the topside dries out. Container plants need 1) more water than ground plants and 2) more fertilizer than ground plants.
This is mostly due to the water just running through the container and being wasted. That is why it is important to keep the weep holes about 2" off the bottom of the containers. I have never had an issue with root rot. By the time tomatoes, zucchini, cucumber, peppers, etc are large and producing fruit, that reservoir will be drained almost daily.
Also, if you like terracotta pots, paint the INSIDE with oil paint like Rustolium. Use cement to plug the hole in the bottom of the pot, and use a ceramic drill bit to drill a hole 3/8" in the side of the pot 2" off the bottom. Now the pot will have a reservoir and not lose all its moisture through the sides of the pot.
Pics are:
1) painted inside 20" pot with cement plugging hole in bottom.
2) Hole drilled in side of pot.
3) A huge amount of Thai peppers being obviously too closely clustered in an obviously too small pot by basic garden rules. Works for me and I get huge amount of peppers.
4) The HD containers. Jalapeno on the left, Bell peppers on the right. Notice how I use bamboo (free here) to enclose the container rather than steak each plant. Works really, really good.
5) Put these trellis in the pots and grow squash on left, cucumber and zucchini on right. Vining plants like cucumber and squash avoid a lot of rot, bacteria, and but issues by making them climb. Worked well for me.
