August 11, 2013
Dioon spinulosum cycad in Phoenix, Arizona
First, and foremost, these plants need shade. Even too much morning sun can sunburn the leaves and cause stunted growth. This plant is in "prime real estate" as it gets the shade from the olive tree in the morning, and the shade from the house in the afternoon. It gets a little bit of dappled sunlight, which appears to be just perfect.
Even though this particular species gets tall in the wild, it takes over 100 years to get to the size of a small palm tree. Like all cycads, it's a miniature. It's just a big miniature (I guess like jumbo shrimp). Mostly I just treat it like a fern.
In spite of the illusion of looking fern-like, it's spiny. So be sure to plant it well away from where people will walk. This is essentially true of all cycads, including "sago palms". They really don't need a lot of vertical space, but they need horizontal space.
Like all cycads, too much water can kill a dioon spinulosum, but it tends to like a little bit more water than your average cycad. It's planted in free-draining, sandy soil, which I have amended with coffee grounds and plenty of slow-release dry plant food.
Since cycads only grow once a year, in sudden flushes, this is the time to do foliar feeding. That is, fill a nice big watering can with water and a water-soluble plant food (like Miracle Grow), and pour it on the leaves and at the base. Be as generous as you want during this growing period. It will take a few weeks for the new flush to finish up. The leaves will darken a bit, and they will harden. Be sure not to touch them while they are young, as any damage you do to the leaves now will be permanent.
If you can find these plants at a nursery in the Phoenix area, they are very expensive. But they really aren't all that rare. You can find them at any Home Depot or Lowe's in the Los Angeles or San Diego area, where they are very common. That's where this one came from.
Posted by Brad Hall