There's a circle to life ... a meme used in everything from books to movies to, well, blog posts like this one. And this is true in the world of plants and produce.
We get comments from clients from time to time along the lines of "it's really not growing as well as it used to" or "I'm not getting a lot of new leaves." Then we might get a picture like the one here.
But plants have cycles too, and the ones that we grow and eat even the more so. Take a leafy green like lettuce or kale. Hydroponically, we get these to come to a head typically within 30 days, at which point in time it is ready to be harvested and eaten. If it is a head lettuce, that's it, it has grown and it is ready to be eaten. If it's loose leaf, like kale or bok choi, you can harvest the lower leaves, and it will continue to grow ... but only for a time. Eventually, it'll move into the reproductive stage, send up a shoot to produce seeds so the circle of life can start again.
So don't be afraid to replace your plants. You're growing healthy, homegrown produce for consumption, so consume! and grab more seedlings from our hydroponic nursery to replace them!