Can you find an in-between size pot? The box is very large. You want something about 1-2 gallons for the next size pot.
Also, you have spider mites and the plant looks hungry. You should treat for mites immediately (pyrethrin bombs, at least twice, spaced 2-3 days apart, then a light mist with neem oil a couple times a week until 4 weeks before harvest). Test the pH of the soil runoff to see if you are locked out because of pH problems.
A large wooden crate like that is more an outdoor type of container. Hint: GREAT for growing potatoes!!! Just dump it out to harvest!