I have had this Yucca for almost a year and around two months ago I started noticing this happening. The plant is next to a north-east window. Generally, Yucca is watered every 10 days. I always make sure that the soil is dried for about 2 inches in depth.
What am I doing wrong? What is happening?
It is probably not getting enough sunlight. Unless you are in the Southern Hemisphere, a northeast window is not enough for a yucca. Yucca need full sun. Assuming you are in the Northern Hemisphere, I would move it to a south facing window for winter. In summer it would be happiest outside in the full sun.
A Yucca is a type of succulent. It store water in it's trunk and uses it when it is dry. In winter indoors it will be in a semi-dormant state. While in this state it will need much less water. The pot should be allowed to completely dry before you water again, not just the top two inches. In summer you can switch back to watering it when the top 2" are dry. When you do that you are allow the rest of the pot to stay moist. Your plant will grow in summer. It should be fertilized only in summer, when it is growing.
In conclusion; move it to a brighter window. A window where the light hits the entire plants would be preferable. Water only when it it fully dry. In spring you will slowly increase the amount of water. In summer water when the top two inches are dry. Put it outside if possible, if not keep it by a bright window year round.
