Do you eat the stem/leaves other than the peas? If so, nitrogen fertilizer is preferred especially organic fish emulsion You don't have to worry about its height if you keep pitching off the top 3-4 inches (or the end 3-4" of its branching out) for stir fry. If you water in the morning/evening, you waste less water by way of evaporation.
4 I4 d; G+ p5 U0 GThat is what I usually do; eat the stems/leaves for a couple of months, when it is close to the end of the season, you will see them rush to flower, then you can stop pitching and wait for harvest of the peapods.