I have been trying to get the top of a pineapple to root in water, and after some weeks I think it finally is. The roots are about 1/2 inch long right now — how long should they be before I transfer it to a potting medium/perlite mix? Thanks so much!
The roots should be at least an inch or more long. Then, put it into a 4 or 6-inch clay pot using a damp soilless, peat-based potting mix. Water thoroughly whenever the top inch of soil feels dry. Gradually increase the light so that it ends up on a sunny windowsill.
Pineapple plants do best in direct sun and warm temperatures (above 60 degrees). If you move yours outside in the summer, introduce it to direct sun gradually over the course of several weeks. You can increase the chances of flowering by keeping it quite potbound in a peat-based potting mix. Water thoroughly whenever the top inch of soil feels dry. Fertilize regularly at half strength when it is in good light and growing vigorously.