Coast redwood cuttings turning yellow
I have some Coast redwood cuttings in soil. The softwood cuttings were taken from a healthy tree 2 months ago.
They were doing very well: four inches of new growth in just a couple of weeks! However, the last couple of weeks there has been no visible growth at all. The tips of the leaves on the new growth are turning yellow.
They are in a plastic container with a constant 80% humidity. Artificial lights (CFL) are on 16 hours per day with no additional natural light source. I don't expect heat to be the problem since the 65w CFL (6400k) is at 1 ft distance from the top of the container and the temperature is between 68 and 70 degrees all the time (measured directly under the containers lid)
I read that yellowing leaves can indicate that the cuttings in fact have rooted...that would be good news. These cuttings are precious to me, so I don't want to pull them out to check....
What is happening to them and what can I do to help them?