Early August and the square foot garden has survived a hot July. There were 21 days with temperatures 90ºF/32ºC and above, with very little rainfall, 1.48"/3.75cm of actual month total precipitation compared to 4.35"/11cm normal month total, as reported by Weather Underground. With the help of irrigation and nighttime temperatures over 70ºF/21ºC the tomatoes and peppers are ripening. I am picking grape/cherry tomatoes daily.
From top center, Orange Bell Pepper, Chocolate Cherry Tomato, Green Bush Bean, Cayenne Pepper and Husky Cherry Tomato
This is a sample of the harvest on 2 August. Not much, I will admit, but great in a salad.
From top right clockwise, Red Bell Pepper, Super Sweet Tomato, Early Girl Tomato, Green Bush Bean, Husky Cherry Tomato and German Johnson Tomato
One of the important needs of any plant is water. Knowing the amount of water needed is essential. Rain provides some, if not all, water to an outdoor garden. A mix of rain and irrigation will most likely be needed.
It is recommended that each square, in a square foot garden, get 1 gallon/3.785L of water per week. Assuming you get some rain, you need to know the amount of rainfall in volume measured in gallons/liters. Subtract the rainfall from the gallon/3.785L and you have your answer.
Use a rain gauge or check the weather report for your area to determine the amount of rainfall received. I use Weather Underground. There is actually a weather station within the .5miles/.8K of my house. I assume the rain amount reported at that station is the amount of rain my square foot garden received.
If the rainfall reported is 1.6" for the week, the square foot garden does not need supplemental watering. If not, it will need irrigation.
Let's start with the fact that 1 gallon = 231.00 cu.in. Each square foot needs one gallon of water/week.
It is always better to deliver the water to the soil and not by spraying from the top. Watering cans, soaker hoses and drip irrigation are the best methods. Watering cans will eat a good bit of time out of your day. Fill the cans, transport the can to the garden, deliver the water and repeat. Soaker hoses and drip irrigation only need to be turned on, timed and shut off. You will, however, need to calibrate soaker hoses to get the volume of water delivered within a certain period of time. The last and most reliable is a drip irrigation system.
Drip irrigation uses calibrated emitters. Emitters come in varying sizes, 1/2G/hr, 1G/hr. 2G/hr or 6G/hr. Just do the math. Turning on the irrigation system for one hour using 1G/hr emitters will supply the proper amount of water needed for one week. Compensate for any rainfall for the week and you will have happy productive plants.