When growing tomatoes, the chemical balance of the root zone is very important. Too much nitrogen will hurt yield, too little phosphorus will hurt yield...etc. Liquid fertilizers are sold based on different combinations of nitrogen, phosphate, and potassium. The Smart Garden will be able to deliver specific amounts of nutrients to each plant using the pumps shown below:
The items that are taped on to the pump terminals are flow meters, which will be discussed in detail later.
As noted before, the pumps were found on Adafruit:
The flow sensors were also found on Adafruit: