I had a Century Guava (世紀芭樂) shipped over from Taiwan to zone 9 California. It is nearly 6 feet tall. I planted it in the biggest container that IKEA sold, 20 inches wide, 2 feet deep. I drilled many holes on the bottom and ensured that water drains out. While the nighttime temperature was below 50 degrees Fahrenheit, I kept the guava inside near a south facing porch door. When the nighttime temperature stabilized to 50 degrees, I moved it outside so that it would get 10 hours of sunlight everyday. Daytime temperatures are averaging 75 degrees. The lower leaves have been slowly becoming yellow. The yellow leaves are dropping slowly at the rate of 2 per week. There are no pests above ground level. However, there are many small black flies living underneath the mulch, which all my other potted plants have, but those flies seem innocuous to those other plants.
At first, I thought I was underwatering it. Although the upper leaves were big and green, they had a crispy feeling, as if it would snap in half if I bent it. I increased watering to 1 gallon twice a week, enough to make water drip out of the drainage holes. However, I think tropical guava leaves are naturally drier than other fruit trees. I visited a local nursery and also felt the same dry crispiness on their tropical guava.
I only put a tiny bit of slow-release tea leaf fertilizer that my florist gave me. I also put a tiny sprinkling of Job's 4-4-4 organic powder fertilizer. I was scared of root burn on a newly planted tree, so I just put a dash of each.
It's supposed to bear fruit like the photo below. The flesh is white and crispy.