How to programme some leds to show growing time of herbs planted in planters.

Hi,

I would really appreciate any info on best components and approach to programming some leds to identify a particular growing time for whatever is planted into some window sill hydroponic planters(sealed drainpipe kinda thing) for micro greens. Ie green when ready to harvest, yellow/orange if a little over and red needing urgent attention. Just for a quick visual guide of what to use from where.

I'd imagine it be a simple counter system but I'd like the ability to assign profiles to different greens with different schedules...

My experience programming is minimal but I have had exposure to certain things in my varied maintenance roles.

I plan to contain all electronics within the planter for mobility and hopefully powered from a small solar and battery set-up.

Sorry for any stupid questions I may ask in advance ......

And thank you to anyone able to help.