Q.What Is Happening With The Leaves Of My Pandanus Amaryllifolius?
I live in San Diego, California. The pandan plants were brought indoor November 1st. They received 10 to 12 hrs. of grow light, watered once a week or when surface is dry. Soil is moist according to moisture meter. 3 out of 6 plants have leaves that wither about an inch from leaf tips inward. It affected all leaves from new leaves in the crown to the outer leaves. The young shoots at the bottom of the mother plants are affted the most. The other 3 plants have healthy dark green leaves but have patchy or yellow spots on them. Please see pictures. Thank you.

Certified GKH Gardening Expert
They need less water during their dormant period so make sure it isn't getting too much water. Also, it looks like it may have spider mites. To remedy this, spray the top and bottom of the leaves with Neem oil. Here is more:
https://www.gardeningknowhow.com/houseplants/screw-pine/indoor-screw-pines.htm
https://www.gardeningknowhow.com/special/tropical/overwintering-tropical-plants.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-control.htm