Impressive winter growth for office coconuts (Beijing, China 40 deg N)

April 27

Hi All,

Inspired by some posts on here, I decided to try my hand at some indoor coconuts. I am originally from S. FL, and after a trip home in early 2024, I came back to Beijing wanting a little reminder of home in my office, which is blessed with a large, south-facing window. I ordered two approximately 1 year old coconuts (a dwarf cultivar, but the seller couldn't tell me more than that, still with mostly strap leaves), a bottle palm, a royal and a foxtail. Beijing has hot, humid summers, so these plants spent approximately 4 months outside, growing happily. In mid-September, I had to bring them in, hoping only to keep them alive over the winter until they could go back outside.

Surprisingly to me, they grew very quickly this winter. My goal was to have them keep pace with winter growth of Malayan dwarfs in S. FL, which has been wonderfully documented in this paper (https://journals.ashs.org/hortsci/view/journals/hortsci/33/6/article-p995.xml). Attaching a figure from that paper. The indoor coconuts ended up blowing away S. FL outdoor coconuts over the winter. I took careful measurements of weekly growth. New leaves appeared every 4-6 weeks, appearing more and more quickly throughout the winter. Both grew five new full leaves between mid-Oct and mid-April. The weekly growth of these leaves also increased with each new leaf, more or less proportional to the final length of the leaf (maxing out at about 20 cm/week for each).

The secret to the fast growth seems to be the giant south-facing window, which is very large in comparison to the size of the office. The coconuts got about 4-5 hours of direct sunlight a day. They were supplemented by one barilla LED grow light each, although I have no idea whether this made any difference, because I could never bring myself to experiment by withdrawing the light from one of them for a period of time and looking at the effect on growth.

The large windows also led to serious heating during the day, with an average high around 85F, and average low around 72F between Nov-Feb. Three humidifiers kept the dew point around 70F, despite dewpoints as low as -20F outside. I made sure to arrange any meetings in my office in the morning, because most people couldn't handle the afternoons. I watered the palms once every three days, and fertilized every three weeks.

They are finally about to go back outside, but they really gave me a glimpse of what is possible for an indoor coconut, if you don't mind sweating a bit!