Recycled coffee grounds give sago palms needed jolt
Published: Tuesday, April 23, 2013 at 3:12 p.m.
Last Modified: Tuesday, April 23, 2013 at 3:12 p.m.
The next time you go to dump the coffee grounds from your morning brew, think again: That nasty-looking slush might actually be one of nature's best fertilizers — especially for a plant with ancient roots that is commonly found in Florida.
The plant is called the cycas revoluta, commonly known as the king sago — and it resembles a mini palm tree. It comes from Japan and has roots that are several million years old.
When Jeffrey Rubin, a retired doctor in Micanopy, bought his property in the mid-1960s, a lone sago palm stood by an oak tree. The previous owner of the house said she had planted it in the 1930s, Rubin said.
“It was love at first sight,” he continued.
Rubin now has nearly 100 sago palms scattered around his 32-acre property.
So when a snow-like white dust appeared a decade ago on the tops and bottoms of the leaves of the beloved plants, Rubin tried a quick salvage with insecticides. The culprit was Asian scale, an insect-bred disease that was brought to Miami from Asia in the early 1990s. Although it initially was believed that the bugs would stay in the warmer climes of South Florida, they made their way north — lying dormant in the plant's roots during the winter. The insects suck the juices out of the plant's leaves and eventually will kill the plant if untreated.
When the insecticides didn't work, Rubin turned to another solution he'd read about: coffee grounds. The alkaloids in coffee — namely caffeine — prevent the insects from eating certain plants, including the sago.
Rubin read about a Lakeland man named Tom Broome, the owner of the Cycad Jungle nursery there, who had been able to kill the Asian scale using a coffee ground solution that he sprayed both on the sago plant's infected leaves as well as its roots.
“For the last 7½ years, I haven't used an insecticide in my nursery,” Broome said. “I have 500 species of plants. The coffee as a direct contact spray will kill any mealy bugs, scale, aphids, whiteflies, spider mites.”
Broome added that the solution “is slightly fertilizing at the same time.”
For about 10 days, Broome steeps the coffee solution — which uses six to seven pounds of coffee grounds for a 55-gallon mix — much like sun tea. The solution — stored in a barrel — lasts about five months.
Spraying is good for treating infected leaves and roots, but coffee grounds alone can be used as a mulch to prevent Asian scale as well, Broome said.
Coffee grounds help turn tide
That's what Rubin does: Every Thursday, he goes to downtown Gainesville's Volta cafe and loads several pounds of that week's leftover coffee grounds into the back of his pickup truck. Back home, he dumps the grounds into a wheelbarrow, and then spreads them on the sagos with a red bucket — or his bare hands, yellowed from contact with so many grounds over the years.
He does this about once a month, according to a schedule he keeps on yellowed sheets of lined paper that hangs in his woodworking studio. There's also a hand-drawn map dividing his sagos into six different zones.
Rubin hasn't had a resurgence of Asian scale since he turned to coffee grounds, but he said he can't credit the coffee entirely. He also uses horticultural oil and an insecticide called Safari. But using the coffee grounds, he said, “allows you to use much less spray.”
Rubin also scouts nearby landscapes for diseased palms.
“Whenever we go to Lakeland, or Ocala, I stop in and tell people what to do, and they think I'm crazy,” he said. His message is always the same: “Instead of throwing the coffee grounds in the garbage, throw them on your garden — it's not going to do any harm.”
Catharine Mannion, an associate professor at the University of Florida's tropical research and education center in Homestead, cautions against relying exclusively on coffee to cure Asian scale, though.
“It seems like there's enough anecdotal evidence to say that it works ... but we do just have to be careful because it might not be the coffee,” she said, adding that she also recommends using horticultural oils and Safari, as Rubin does.
Broome, however, already has started successfully using coffee grounds on some of the other 500 species of plants in his nursery, including hibiscus and pepper. He recommends people mulch with straight grounds twice a year — around March and August — to prevent Asian scale, and spot-spraying infected leaves.
Broome added that the plant that was starting to fade from Florida landscapes because of Asian scale is now making a comeback.
“Several botanical gardens have used that to clean up their plants,” he said of the coffee solution. “More people are selling sagos because now they have a way to combat the scale.”
And for Rubin, that preservation is essential. He keeps another sago plant — an ancestor of the king sago — in a greenhouse he built 40 years ago. Called the dioon spinulosum cycad, the leaves of the plant resemble something between latticework and sculpture.
“It's like a work of art,” he said.
Contact Kristine Crane at 338-3119, or firstname.lastname@example.org.