“It only takes spinach about a week to go from seed to seedling, and then forty days later, you can expect to harvest your plants and toss them in a salad. In that time, our system will not need to have its water changed so long as the nutrient solution to plant ratio remains at one plant to one gallon. A pH level between 6.0 and 7.5 is necessary. This pH level is mostly within the ranges that lettuce likes as well, and this means that the two plants can be grown together in a single Kratky system, though lettuce will harvest a week or two earlier than spinach does.”