Heat is the bane of LEDs.

The recommended method to find the maximum current used to illuminate an LED is by measuring the temperature. The easiest way to measure the temperature is with your finger. You should be able to hold your finger on the back side of the PCB the LED is mounted on for 10+ seconds with no significant discomfort.

Strips of White LEDs are the Most Economical

Bridgelux LED Strips are an economical choice. You can find 22" strips for between $5 - $10. These strips also have very good efficiency (photons/watt).

Plants Feed on Photons, Not Lumens

A Bridgelux EB Slim Gen 3, 23" strip's luminous output ranges between 2085 lm and 2675 lm.
Which one radiates more photons?