I am a beginner at hydroponics, and want to grow celery and water spinach. However, I do not know what the light requirements (lux) are. Searching online doesn't help at all unfortunately. I have read this question, but this question is asking about different plants.
Approximately 80-100k will be adequate. Too much more than that (150-200k) and you'll risk having too much which if I recall correctly can cause lettuce to flower (due to the heat concentration). - @Enigma
This answer is for lettuce, but is there such a range for celery and water spinach?
The units can be in PPFD too.
I have a problem though, I want them to grow in outdoor hydroponics, so the weather is constantly changing, so the light range can vary.
