Chocolate, Anyone?
Posted at 5:06 pm January 17, 2007 by Seth Menser
Being a gardener at the San Diego Zoo has many responsibilities that a gardener anywhere would have, like pruning hedges and fertilizing trees. What makes being a gardener here so much more rewarding than elsewhere is the many unusual jobs in which we get to be involved. Planting flora from all over the world to create exotic environments at the Zoo is one example. Another might be researching what kind of plants can be used in a primate exhibit. One exciting project we started recently was very unusual and struck me as a great topic for a blog. The experiment involves growing the plant that chocolate comes from, a very tropical plant in our mild, non-tropical climate.
Growing very tropical plants outside has been tried at the Zoo before, but the problem of cool, damp soils in the winter seems to be the biggest killer. The cacao plant Theobroma cacao, source of chocolate, comes from the tropical rain forests of Central and South America–places that rarely get colder than 60 degrees. How could we create an environment where a cacao tree could survive outdoors in cooler temperatures? An idea came to Mike Letzring, the Zoo’s Horticulture Collection Manager. His plan was to create a heated area in the soil just below the plant, similar to heat benches for seed germination in greenhouses. This would help keep the roots warm all winter long.
With our plan in hand, we began our ” chocolate experiment” in an area off-limits to the public. First, what was needed was a chocolate plant; luckily there were several growing in our greenhouse. Next, we built a 30-inch box made of insulation board, the kind you would use to insulate walls in homes and other buildings. After making drainage holes in the bottom of our insulated box, we added a few inches of well-amended soil. Our heat source, heating cables regulated by a control box, was coiled out and laid on top of the soil. Six more inches of soil was placed on top of the heating cables. Once the chocolate plant was planted and backfilled, a layer of mulch was spread over the whole area.
Over the course of the experiment, regular soil and air temperatures will be taken and recorded. This information will come in handy to us if our planting is successful. Although this very cold winter has been uncomfortable, the low temperatures will actually work to the advantage of the experiment, in that they provide an extreme temperature variable. Check back in a few months for an update on how our chocolate plant is doing. Who knows”¦maybe sometime down the line we’ll be able to make our own chocolate bars!
Seth Menser is a gardener at the San Diego Zoo.
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January 18th, 2007 at 10:38 am
Seth, Oh My God what more could you ask for the zoo, plants and chocolate. I would think i died and went to heaven. besides being a challenge to grow chocolate plants this could also be a great source of revenue for the zoo, chocolate in all the shapes of animals and just chocolate, chocolate, chocolate. You and your crew are doing a great job and all the plants, trees and the gardens are gorgeous, keep up the great work.
January 18th, 2007 at 1:03 pm
Fabulous, Seth! What an ingenious solution. Is there anyway you could use the heat from animal manure under the soil to keep its temperature regulated? I know they use ” Zoo Doo” for fertilizer, so why not put it to use as a heat generator for plants.
You have such an interesting and exciting job in one of the world’s most unusual and interesting places with limitless creative outlets.
January 21st, 2007 at 2:29 am
I think Margaret just gave you a name for your home-made, animal-shaped chocolate bars. Can’t wait to buy a Zoo-Doo bar at SDZ!
Seriously, Seth, thanks for another backstage look at the fascinating work done at your great zoo!
March 8th, 2007 at 9:27 pm
i am obsessed about chocolate yaaaay chocolate
January 28th, 2008 at 3:52 pm
I guess it is a wonderful place to work in. I always loved the Zoo and asked my mom repeatedly to take me there. We went at least once a year and always made a big donation for the animals.
February 28th, 2008 at 6:51 am
Hi Seth,
I’m a member of the California Rare Fruit Growers society. Curiosity is nagging me to find out how your cacoa tree is doing. Also have you determined what heat characteristics have been generated by your coils? Do you have a descriptive of your layout–a schematic, etc.? This will be a wonderful project with a delicious outcome if it’s successful and practical. Raw organic chocolate nibs are like manna from heaven.
Richard
March 5th, 2008 at 8:21 pm
Richard,
Bad news-the chocolate plant did not make it through last winter. I think the combo of cold weather and dry Santa Ana winds did it in. This and I think the heating coils might have keep the soil too dry and toasty. We still have two large chocolate trees in our greenhouse and are looking at warmer, more protected locations for a future planting/experiment.
Seth
February 14th, 2009 at 1:58 pm
I would like to come and get or buy zoo doo. Could you let me know if this is possible and how to go about it?
Thank you,
MEG
Moderator’s note: We don’t sell or make zoo doo available to the public. Because the San Diego Zoo is a quarantine facility, all animal waste is disposed of according to government regulations.